White Paper

Comparative Analysis of Steam Sterilisation versus Low Temperature Sterilisation in Specialised Clinics in Australia

August 2025

Disclaimer

This content is provided for information only. The authors make no representation or warranty regarding the accuracy, completeness or currency of the content. No information in this whitepaper should be construed as medical advice. Readers should seek appropriate professional guidance before acting on any information contained in this document. The authors expressly disclaim all liability for any direct or indirect loss or damage arising from the use of or reliance on this information.

Abstract

This whitepaper examines the performance, compatibility, operational requirements, compliance, cost, and environmental considerations of steam sterilisation and low temperature sterilisation in specialised clinics across Australia. It is intended to guide decision makers in clinic management, biomedical engineering, and infection control in choosing appropriate sterilisation methods for hospitals, nursing homes, day surgeries, and dental clinics.

Sterilisation Methods Overview

Steam Sterilisation (Autoclaving): Steam sterilisation uses pressurised saturated steam at high temperature typically 121 to 134 °C to achieve rapid microbial kill. It is the gold-standard method for sterilising heat-tolerant medical instruments due to its reliability and efficacy. Steam readily penetrates porous loads and lumens, and its cycles are fast, often 20 to 60 minutes. Autoclaves range from large hospital units to small benchtop sterilisers used in dental or clinic settings. Steam is non-toxic and leaves no residues, but it cannot be used on heat-sensitive devices e.g. certain plastics, electronics which would be damaged by high temperature.

Low Temperature Sterilisation (LTS): Low temperature methods are used for heat and moisture-sensitive medical devices that cannot withstand autoclaving. A variety of chemical sterilants and technologies fall in this category:

Ethylene Oxide (ETO) Gas: A traditional low-temperature method using a flammable, toxic gas (ETO) to alkylate microorganism DNA. Effective for devices sensitive to heat/humidity, including plastics and electronics, and highly penetrating even into long lumens. However, ETO sterilisation is very slow, for example the total cycle including aeration can exceed 12 hours and requires thorough post-sterilisation aeration to remove toxic residues. ETO is carcinogenic and heavily regulated due to worker and environmental safety concerns. It has largely been phased out of small clinics and is now mostly used in large hospitals or outsourced reprocessing centers for delicate items that no other method can sterilise.

Hydrogen Peroxide Gas Plasma/Vapor: This is a widely adopted modern LTS technology. It uses vaporised hydrogen peroxide (H2O2), often energized into plasma form, to produce reactive free radicals that destroy microbes. The process runs at ~40 to 50 °C, making it suitable for heat-sensitive and moisture-sensitive instruments. Cycle times are short at ~28 to 75 minutes and no aeration is needed since H2O2 breaks down into oxygen and water. It is safe for most materials including metal instruments and electronics. However, cellulose-based materials (paper, cotton) cannot be processed as they absorb and inactivate the peroxide. Special synthetic packaging and plastic trays are required instead of standard paper packaging. Hydrogen peroxide sterilisation leaves no toxic residue and is considered environmentally benign, though the chamber size is typically smaller than steam autoclaves and some long or narrow lumens are not compatible due to diffusion limits.

Ozone Gas: Ozone sterilisation uses O3 gas generated from oxygen and water inside the machine as a strong oxidising agent. It operates at low temperature around ~30 to 40 °C, with some systems adding humidity up to ~80 to 95 °C. Ozone effectively kills microbes and spores, and modern ozone sterilisers convert O3 back to oxygen and water at cycle end, emitting no toxic residues. It is safe for operators and environmentally friendly in terms of by-products. Ozone is compatible with many materials such as metals, glass, most plastics but cannot process cellulose, textiles, or liquids. A major drawback is cycle time, typically about 4 to 4.5 hours per load. Ozone units also tend to be physically large, often floor-standing, akin to a refrigerator in size and may require an oxygen source such as a built-in generator or external O2 supply. These factors can limit ozone’s practicality in clinics that need quick instrument turn-around.

Low Temperature Steam Formaldehyde (LTSF): This older method used more in Europe combines low-temperature steam ≈60 to 80 °C with formaldehyde gas infusion. It is effective for devices that can tolerate mild heat and requires ~1 to 2 hour cycles. LTSF is noted to be suitable for certain items like hemodialysis equipment and some plastics. However, formaldehyde is toxic, irritant and a suspected carcinogen, so stringent ventilation and safety measures are required. The formaldehyde gas is neutralised or flushed at cycle end, as it naturally breaks down over a couple of hours. Due to safety and regulatory issues, LTSF is now uncommon in Australian health facilities.

Note: Device compatibility varies with each low-temperature method, so manufacturers’ instructions must be followed. A device should only be sterilised by methods proven compatible with its materials and design. For critical devices, written confirmation of compatibility from the device manufacturer is prudent, and steriliser manufacturers provide guidelines on which materials and lumen dimensions their process can handle. In practice, hydrogen peroxide and less commonly ETO are the dominant low-temp methods in Australian hospitals, with ozone emerging in some settings; formaldehyde and liquid chemical sterilisations are rarely used or recommended.

Performance and Efficacy

Microbial Kill Efficacy: All the above sterilisation methods, when properly used, can achieve a sterility assurance level of 10^-6, a probability of less than one in a million of a viable microbe surviving. Steam sterilisation is widely considered the most robust and rapidly microbicidal method, with broad-spectrum efficacy against bacteria, viruses, fungi, and hardy bacterial spores. High-temperature steam causes coagulation and denaturation of cell proteins, rapidly killing even resilient organisms. Steam is noted to be the least affected by organic soils among sterilants, while pre-cleaning is still essential, small residual amounts of blood or tissue have less effect on steam efficacy than they would on chemical sterilants. Steam cycles especially at 134 °C achieve complete kill in a short exposure, e.g. 3 to 18 minutes depending on load, making it ideal for high-throughput settings. Additionally, steam can penetrate porous loads and small lumens under vacuum cycles, ensuring all instrument surfaces reach the lethal conditions.

Low-temperature processes are also lethal to microbes but often have specific performance considerations. Hydrogen peroxide gas plasma, for instance, has rapid biocidal action including sporicidal activity under the right conditions. Its efficacy depends on achieving the proper concentration and contact time of the peroxide gas on device surfaces. Modern H2O2 sterilisers run automated cycles that carefully control these parameters, and biological indicator testing shows they reliably reach sterility for loads within their design specifications. However, items with long, narrow channels can be challenging, e.g. some flexible endoscopes or long tubing may exceed the dimensional limits that peroxide gas can penetrate effectively. Manufacturers specify maximum lumen length and diameter, for example, a common plasma steriliser might accept stainless steel lumens up to 1 mm inner diameter and 500 mm length, beyond that, sterility in the lumen cannot be assured. Thus, performance is excellent for suitable items but very narrow or intricate instruments might not be effectively sterilised unless validated for that system.

Ethylene oxide is highly penetrating and effective against all microbes, given sufficient time. It can sterilise complex devices including long catheters, multi-channel endoscopes, or equipment with electronic components because the small gas molecules slowly diffuse into tight spaces and throughout packaging. ETO’s lethality is augmented by humidity and moisture helps ETO penetrate microbial cells, so a humidification step is often included. Its downside in performance is speed, a typical ETO cycle involves 1 to 4 hours of gas exposure at 37 to 55 °C, then 8 to 12+ hours of aeration to purge residual gas. The lengthy process means ETO cannot provide rapid instrument turnaround, and if instruments are needed sooner, ETO is not practical. Moreover, any organic debris or salts on instruments can impede ETO efficacy by reacting with or blocking gas, making thorough pre-cleaning critical. In terms of microbial kill, ETO is very potent, a well-established sterilant for even spore-formers and viruses, but its use is now often restricted by safety and time factors rather than efficacy concerns.

Ozone sterilisation is also an effective sporicidal process. Ozone is a strong oxidiser and can destroy microorganisms but requires sufficient concentration and humidity. Its 4+ hour cycle is a performance limitation mainly in terms of workflow, not kill ability. The long exposure ensures even hardy spores are inactivated. Ozone’s penetration into certain materials or lumens is generally good, though like other gases it may struggle with very long narrow lumens if flow is restricted. Newer ozone-based systems that combine H2O2 and O3 claim improved lumen penetration and shorter cycles by using sequential or combined sterilants. Overall, ozone’s sterilising efficacy is high, but its practical performance in a clinic is curbed by slow cycles and large equipment size.

In summary, steam sterilisation offers unmatched speed and reliability for durable devices, achieving rapid high-level disinfection and sterilisation in minutes. Low-temperature methods, while equally lethal when used correctly, must be chosen to fit the device type: they are indispensable for instruments that would be destroyed by steam, but each has unique cycle times and compatibility constraints that affect real-world performance. All sterilisation processes require that instruments be meticulously cleaned beforehand and retained soil can protect microbes or interfere with sterilant contact. Notably, steam’s high heat provides some margin against residual soil, whereas chemical low-temp methods can be neutralised by organic matter or may not penetrate dried debris. Thus, strong cleaning and quality control programs are a prerequisite to ensure any sterilisation, for example steam or low-temp achieves the intended efficacy.

Finally, prions, the agents of diseases like CJD deserve special mention in performance: prions are extremely heat- and chemical-resistant. Standard steam cycles 134 °C for >18 minutes are one of the few methods known to inactivate prions on surgical instruments, whereas low-temperature gas/plasma methods are not verified for prion destruction. For this reason, high-risk neurosurgical instruments either undergo extended steam sterilisation or are single-use if prion disease is a concern. While prion cases are rare, this underscores that steam remains the preferred method for the highest level of pathogen inactivation when materials permit, and low-temp methods are used to balance device preservation with adequate microbicidal action for all other pathogens.

Material and Device Compatibility

Choosing a sterilisation method depends heavily on device material compatibility. Steam sterilisation is suitable only for items that can tolerate high heat and moisture. Stainless steel surgical instruments, glassware, and robust polymers like polysulfone or autoclavable plastics handle steam cycles well. These materials do not deform at 134 °C and are not harmed by water. In fact, surgical stainless steel and titanium instruments are routinely steam-sterilised hundreds of times with minimal impact, aside from possible dulling of fine edges or corrosion if not properly dried. Heat-sensitive materials, however, cannot withstand steam, examples include many plastics e.g. polyethylene, PVC, low-melting point polymers, latex and silicone items which can degrade or become brittle with repeated heat, and electronic components or batteries. Fine optical components and powered equipment such as cameras, light cables and ultrasound probes usually cannot go in an autoclave without damage. Additionally, some delicate instruments, even metal ones can be damaged by repeated steam cycles: e.g. ophthalmic microsurgical tools or laparoscopic instruments with plastic insulating parts may degrade over time with constant high-heat exposure. Steam can also cause rusting if instruments are not adequately dried or are made of suboptimal alloys. Thus, while steam is broadly compatible with many reusables, anything not explicitly marked “autoclavable” by its manufacturer should be assumed incompatible with steam.

Low-temperature sterilisation methods offer compatibility with a wider range of materials, but each method has specific limitations:

Hydrogen Peroxide Gas Plasma: Compatible with most metals, medical-grade plastics, and electrical components. It is a gentle process in terms of temperature <50 °C and leaves no moisture, so it won’t corrode metal or electronics. This makes it ideal for devices like endoscopic cameras, fiber-optic cables, battery-operated tools, and plastic instruments that would melt or warp in steam. Notably, H2O2 gas does not significantly penetrate materials like cellulose, paper or linen; such materials cannot be in the load as they would absorb the peroxide and prevent effective sterilisation. All packaging for peroxide sterilisation must be cellulose-free such as Tyvek or polypropylene wraps, polyolefin pouches. Items with dead-end lumens or long narrow lumens may be incompatible because the peroxide gas/plasma may not reach the end of the lumen effectively. Each model specifies the maximum lumen length and diameter it can sterilise. Additionally, certain polymers might undergo oxidation with repeated H2O2 exposure; for instance, some rubbers or coatings can become brittle. Overall, if the item’s manufacturer deems it hydrogen-peroxide compatible, the process will not significantly degrade it, whereas the same item might be destroyed by steam. Hydrogen peroxide is increasingly used for high-tech devices like defibrillator paddles, flexible endoscopes if lumen criteria are met, and sterilisation of single-use devices that are heat labile when hospitals choose to reprocess them.

Ethylene Oxide (ETO): ETO is highly compatible with most materials used in medical devices. Its low-temperature usually 37 to 55 °C and non-corrosive nature mean it can sterilise almost anything: plastics, rubber, silicone, polymers, electronics, delicate optics, all generally tolerate ETO gas well. ETO also penetrates porous materials and packages, so devices in paper-plastic pouches or wrapped in drapes can be processed. A big compatibility consideration with ETO is residuals: many materials especially plastics like polycarbonate or certain adhesives will absorb ETO during sterilisation and then release it slowly. This is why prolonged aeration is required, to allow absorbed gas to dissipate to safe levels. There is a risk that materials with high ETO absorption could retain toxic levels of residue if not aerated properly. Another issue is that some very fine mechanical or optical instruments might be sensitive to ETO’s action over time, for example, repeated ETO cycles could potentially affect certain polymers or lubricants. But in general, if an item cannot withstand steam, ETO is often the next alternative, and manufacturers frequently list ETO sterilisation in their device reprocessing instructions for heat-sensitive equipment. In summary, ETO’s material compatibility is broad and most medical instruments that are not plastic-disposable can be ETO sterilised, albeit with the trade-off of time and safety handling.

Ozone: Ozone gas is a strong oxidiser, so compatibility needs consideration. Ozone sterilisation is done at low heat ~30 to 40 °C and is dry, which is good for electronics and moisture-sensitive items. It is generally compatible with stainless steel, anodised aluminum, titanium, glass, silicone, and many common plastics like polyethylene and polypropylene. However, ozone can react with certain materials: for example, exposed brass, natural rubber/latex, and some polymers e.g. polyurethane may be degraded by ozone. Like peroxide, ozone cannot be used with cellulose-based materials, you cannot sterilise paper surgical drapes or cotton textiles with ozone, nor can you use paper packaging, because ozone will react and be neutralised by organic materials. Instruments that contain cellulosic components e.g. some filter materials or plastic packaging with paper labels need to be avoided or those components removed before ozone processing. Ozone is also not suitable for liquids or wet items, fluids would prevent effective gas contact and could off-gas ozone when handled. Additionally, items must be fully dry before ozone sterilisation as ozone’s efficacy is linked to humidity but pooled water would impede penetration and could concentrate ozone into potentially corrosive acids. Ozone’s material compatibility is thus good for most solid instruments, but somewhat limited for packaging and certain sensitive polymers. Manufacturers of ozone sterilisers provide lists of approved and contraindicated materials, and those should be strictly followed to avoid damage.

Formaldehyde (LTSF): Low-temperature steam-formaldehyde is moderately compatible with medical materials. The presence of 60 to 80 °C steam means items must handle at least that much heat and humidity far lower than autoclave temperatures, but still too high for truly heat-labile plastics. Formaldehyde gas itself can be harsh on some materials: it may cause cosmetic changes e.g. yellowing of plastics or leave residues if not fully purged. However, LTSF has been used on plastics, rubber, and even dialysis filters/membranes successfully, so most items that tolerate warm water vapor can handle LTSF. That said, because of formaldehyde’s risks and the availability of gentler methods like H2O2, LTSF compatibility is less of a practical issue today. Few clinics will choose formaldehyde unless absolutely necessary. Devices that are incompatible with peroxide due to cellulose content and with steam due to heat might be candidates for ETO or LTSF; in Europe, LTSF was traditionally used for items like endoscopes or dialysis equipment that couldn’t go in an autoclave.

Packaging and accessories compatibility: An often overlooked aspect of compatibility is the packaging and accessories used in sterilisation. Steam sterilisation uses materials like medical grade paper, non-woven wraps, cloth textiles, or paper-plastic peel pouches, these must withstand high heat and moisture. Typically, disposable wraps and pouches are designed for steam and will not melt or degrade at 134 °C. Rigid re-usable instrument containers such as aluminium cases are also common in steam and are built to handle repeated autoclave cycles. In low-temp systems, standard steam packaging cannot always be used: as noted, paper products cannot go into hydrogen peroxide or ozone sterilisers. For plasma and ozone, hospitals use polypropylene-based non-woven wraps that allow penetration of the gas but won’t absorb it. Adhesive indicator tape and labels used on packs must also be compatible. Special plastic-based indicator labels are available for plasma, since normal autoclave tape or paper labels would inhibit the process. Each low-temp method has corresponding chemical indicator strips and biological indicators formulated for that process, e.g. spore strips of Geobacillus stearothermophilus for steam vs. Bacillus atrophaeus for ETO, etc., and those indicators are placed in packaging during routine monitoring. The bottom line is that every item in the steriliser chamber must be approved for that sterilant, from the device itself to the tray, wrap, indicators, and any padding or absorbent. A failure to use compatible materials can result in sterilisation failure or damage, for example, putting an instrument wrapped in a cotton towel inside a plasma steriliser would almost certainly abort the cycle or leave the instrument unsterile because the peroxide gets consumed by the towel.

In practice, manufacturers provide guidelines on reprocessing their devices. It is vital for clinics to consult the device’s reprocessing instructions: e.g. a flexible endoscope might say “Do not steam sterilise; use ETO or H2O2 gas plasma according to hospital protocol” or a power drill might specify a maximum temperature for sterilisation. Many complex reusable devices are shipped with a detailed Instructions for Use (IFU) on how to clean and sterilise them; following these is part of both compatibility and compliance. When in doubt, or when introducing a new low-temperature sterilisation system, facilities should obtain written confirmation of compatibility from device manufacturers and even test process a sample device if feasible. This ensures that expensive instruments are not inadvertently ruined and that sterilisation efficacy is not compromised by material issues.

Operational Requirements and Workflow

Steam Steriliser Requirements: Steam autoclaves in hospitals often require plumbing for water supply and drainage, as well as substantial electrical power for heating elements or steam generators. Large steam sterilisers may be floor-mounted devices with steam generator boilers, requiring an HVAC system to manage heat and humidity output. Modern hospital autoclaves usually have a vacuum pump to remove air for pre-vacuum cycles and to aid drying; some use water-ring vacuum pumps that consume significant water, whereas newer models use water-sparing vacuum systems. A well-ventilated room is important because steam sterilisers give off heat and some steam exhaust. Installation must account for space around the unit, potentially a recessed wall design with a “clean” (output) side and “dirty” (loading) side for central sterile departments. In smaller clinics e.g. dental or GP offices, benchtop steam sterilisers are common, these are self-contained units about the size of a microwave oven. They usually only need a standard power outlet and manual water filling or an internal reservoir. No special room modifications are required for tabletop autoclaves aside from a stable surface and some ventilation to handle warm exhaust. Operationally, steam sterilisers need a supply of pure water distilled or deionised to prevent mineral deposits; staff must drain and refill water reservoirs regularly in small units. Loading the autoclave requires arranging instruments for proper steam circulation to avoid overpacking trays or nesting bowls that could trap air. After the cycle, items are hot and often wet, good autoclave practice includes a drying phase, but some tabletop units are not as effective at drying, so staff may need to let packs cool and dry further in the open, which risks contamination if not in a controlled area. Thus, larger autoclaves with vacuum drying are preferred for surgical instrument sets to ensure packs come out dry as moisture can compromise sterility of stored items.

Staff operating steam sterilisers must be trained in cycle selection e.g. 121 °C longer cycle vs 134 °C short cycle, special cycles for liquids or prion inactivation, loading configuration, and monitoring of each run. Australian standards like AS/NZS 4187 and now AS 5369 require routine performance tests for steam sterilisers, e.g. daily Bowie-Dick tests for air removal in pre-vacuum autoclaves, chemical indicator strips inside packs, and regular biological indicator testing. Record-keeping is essential: the steriliser’s print-out or log of time, temperature, and pressure for each cycle should be checked and kept on file. Any process faults such as failure to reach temperature, etc. mean the load is non-sterile and must be reprocessed. Maintenance of steam sterilisers includes periodic calibration of temperature probes, pressure gauges, safety valve checks, and replacing seals and filters. Water treatment systems if used for feed water also need maintenance. Despite these needs, steam sterilisers are generally straightforward to operate and are standard equipment in most medical facilities.

Ethylene Oxide Steriliser Requirements: ETO sterilisation is highly effective but operationally complex. ETO units must be placed in well-ventilated areas or dedicated steriliser rooms, often with a forced exhaust to the outside or a scrubber system, because of the toxic, flammable nature of the gas. Many ETO sterilisers use single-use gas cartridges (ampoules) that are punctured inside the chamber to release a measured ETO dose. Modern designs use negative pressure chambers to minimize risk of leaks, and have abatement systems such as catalytic converters that convert expelled ETO to carbon dioxide and water. Even so, facilities using ETO may require special environmental permits or monitoring. In some jurisdictions, emissions need to be reduced by >99% and environmental agencies regulate ETO release. Hospitals must often install vents or catalytic scrubbers and might need to monitor workplace air for ETO levels to protect staff. Furthermore, ETO cartridges must be stored safely in a flammable materials cabinet and handled with care.

The ETO sterilisation process is lengthy: a typical cycle might be 2 to 5 hours of exposure followed by 8 to 12 hours of aeration either in the same chamber or in a separate aeration cabinet. Aeration at controlled warmth and ventilation is crucial to purge residual gas from the items. This means that turnaround time for any instrument set is about 1 to 2 days, making ETO impractical for fast-paced needs. Operationally, this requires large instrument inventories, a clinic must have spare sets of any instrument going to ETO, since those will be out of circulation for a day or more. Staff must be trained not only in loading and starting the ETO cycle but in handling ETO-sterilised goods: when the cycle is done, items often still contain ETO and cannot be used until aeration completes. Opening an ETO chamber prematurely is dangerous and prohibited. Items must cool and aerate fully; some facilities leave them in a well-ventilated area even after formal aeration to be extra safe. Personal protective equipment (PPE) like gloves and sometimes respirators might be recommended when unloading ETO chambers, in case residual gas is present. Given these requirements, many smaller clinics do not use ETO on-site. Instead, if ETO is needed, they may send instruments to an external reprocessing service or to a larger hospital’s central sterilising department. Those that do invest in ETO systems must commit to significant staff training on hazard handling, emergency procedures for leaks, etc. and rigorous compliance with occupational health regulations.

Hydrogen Peroxide Gas Plasma Steriliser Requirements: H2O2 sterilisation units are designed to be user-friendly and relatively easy to install. They typically require only a standard power supply and do not need plumbing or external venting. The machines are self-contained, converting hydrogen peroxide into plasma and then into harmless water vapor and oxygen at cycle end. This means no special exhaust duct is usually needed, they can be operated in regular rooms though a well-ventilated room is still wise to disperse any trace vapors. These sterilizers are often compact tabletop or cart-size for small models, up to a small refrigerator footprint for larger capacity models, which suits them to clinics and hospital sub-sterile areas. Consumables include the hydrogen peroxide cartridges or cassettes which contain pre-measured solution and sometimes single-use trays or packaging inserts that help with vapor distribution. Each cycle uses one cassette or a portion of it, and costs around A$12 per cycle in consumables as reported. Operationally, plasma sterilisers have fast cycles under an hour and items come out dry and ready to use, with no aeration time needed. This quick turnaround is a major operational advantage, instruments can often be reprocessed between cases on the same day.

Key operational requirements for H2O2 sterilisation include ensuring items are clean and completely dry before processing. Water or moisture can cause cycle failure or suboptimal sterilisation, as H2O2 will react with the water. Staff must also be vigilant about loading configuration: there are usually limits on load density and the position of lumened instruments often they must be on top shelves, etc., to improve sterilant penetration. Another requirement is using the correct packaging, using the wrong packaging can abort the cycle or block sterilant. Staff training focuses on these specifics and on handling the peroxide cartridges, generally they are safe; the user just inserts the cassette and the machine does the rest, so minimal exposure to H2O2 occurs. Because peroxide gas plasma is an automated, low-labor process, once staff are trained, it integrates well into workflow: instruments can be cleaned, dried, packaged, and then just loaded and the cycle started with push-button operation. After cycle completion, often ~45 minutes, staff review the printout and chemical indicators to confirm success, then the instruments are available for use or storage. Maintenance of H2O2 units typically involves replacement of plasma electrodes or vacuum pump servicing on schedules, and calibration of sensors. There is also a shelf-life for the peroxide cassettes to monitor. But in general, peroxide sterilisers are considered simpler to operate and install than large steam or ETO systems, which is why many day surgeries and smaller hospitals have adopted them as their low-temp solution of choice.

Ozone Steriliser Requirements: Ozone systems are less common but have some distinct operational needs. As noted, ozone sterilizers often require an oxygen source, one cannot usually plug into the hospital wall O2 because of flow and purity needs, so units either have an internal oxygen concentrator or use small high-purity O2 cylinders that attach to the machine. They also need deionised water to generate humidity for the process and for the catalyzer that destroys ozone at the end. And, of course, electricity to run the compressor, etc. Installation might involve hooking up a water feed and a drain to dispose of water by-products, depending on the model. Ozone gas is very reactive, but the machines are designed so that by the end of the cycle virtually no ozone is released and converted back to oxygen. Nonetheless, it’s wise to have the unit in a ventilated area in case of any leaks or malfunction. Ozone’s long cycle time (4+ hours) means that operationally, one needs to plan instrument rotation carefully. If an instrument set goes into ozone sterilisation, it won’t be available again for use until almost half a day later. This implies, similar to ETO, the need for multiple instrument sets if ozone is used for items needed frequently. However, ozone units often have a large chamber, some can sterilise many items at once, potentially larger loads than a single plasma cycle. This can mitigate the throughput issue by processing bulk loads overnight. Still, for a busy setting, ozone is not ideal for rapid turnover items; it might be used as an adjunct for a subset of instruments.

Staff training for ozone sterilisation covers the importance of using compatible materials no latex, no cotton in loads, etc. and ensuring that lumens meet the specification, ozone, like plasma, has limitations on lumen size it can effectively sterilise. They also learn how to replace oxygen cylinders or filters as needed. The cost per cycle in terms of utilities is low, around AUD$1 of electricity and water, since no expensive consumable is used each time. But the capital cost of ozone sterilisers can be high, and their footprint is large, so a facility must allocate space and budget accordingly. Maintenance involves servicing the built-in ozone generator/catalyst and any air compressors or concentrators. Given these requirements, ozone tends to be found in larger institutions or in specific contexts, for example, some central sterile departments might use ozone for instruments that can’t go in plasma due to lumen length, etc. Its use in small clinics is limited because the infrastructure and slow cycle are not a good fit unless the case load is very low or very specialised.

General Workflow Considerations: Regardless of method, cleaning and drying of instruments prior to sterilisation is mandatory. Clinics need appropriate cleaning facilities such as ultrasonic cleaners, washer-disinfectors, manual scrubbing sinks because no steriliser can compensate for a dirty instrument. Sterilants cannot reliably penetrate soil to kill underlying microbes. After cleaning, instruments must be inspected, assembled, and packaged for sterilisation. Here, steam and low-temp diverge: staff must decide which method each item will go to, and clearly segregate items by process. Many hospitals have separate areas or distinct color-coded packaging for steam vs plasma, etc., to avoid any mix-ups since an item in paper wrap accidentally put into a plasma steriliser would not be sterilised. Some facilities that run multiple methods will have dedicated sterilisation rooms or cabinets for the low-temp units, often adjacent to the main sterile processing area but partitioned for safety especially if ETO or formaldehyde are used, those might be in a fume-hood or separate room with an exhaust. The Australian standard requires segregation of “clean” and “dirty” work areas in reprocessing, and also essentially segregation between different sterilisation processes to prevent cross-contamination or accidents. Staff scheduling must account for varying cycle lengths, e.g. steam loads can be done quickly even between surgeries, whereas an ETO load might be scheduled overnight. Documentation is another operational aspect: each cycle of each steriliser must be logged electronically or on paper and indicators results noted, to fulfill traceability requirements.

In summary, steam sterilisation is operationally fast and cost-effective but demands a robust infrastructure such as plumbing, heat tolerance, drying. Low-temperature sterilisation systems offer necessary capabilities for delicate devices but bring additional installation needs such as ventilation, cartridges, special packaging and often slower cycles. Clinics making decisions about sterilisation must consider their instrument inventory and case volume: a large hospital typically runs multiple autoclaves all day for general instruments, with perhaps one low-temp unit handling special items; a day surgery might primarily use a tabletop steam steriliser and, if needed, a small plasma steriliser for a few items; a dental office might only have bench steam sterilisers and no low-temp at all, outsourcing any unusual items. Training and proficiency of staff is crucial, operators must know the nuances of each process to avoid errors like damaging an instrument by choosing the wrong cycle, or causing a cycle failure by misloading. Each method also has unique safety protocols e.g. avoid opening a hot autoclave too quickly to prevent burns, wear gloves when changing an ETO cartridge, allow aeration before use, etc.. Adhering to these operational requirements ensures that the sterilisation processes are not only effective but also smooth and safe as part of the clinic’s workflow.

Compliance and Standards in Australia

Sterilisation practices in healthcare are tightly governed by standards and guidelines to ensure patient safety. In Australia, the key standards have recently been updated. In December 2023, Standards Australia released AS 5369:2023 Reprocessing of reusable medical devices and other devices in health and non-health related facilities, which supersedes the older standards AS/NZS 4187:2014 for hospital sterilisation processes and AS/NZS 4815:2006 for office-based healthcare facilities. This new unified standard covers sterilisation and disinfection requirements across hospitals, day procedure centers, dental clinics, office practices, and even non-traditional settings that reprocess medical devices. Its introduction is a significant compliance change, consolidating guidance for both large and small facilities.

Under the National Safety and Quality Health Service (NSQHS) Standards, specifically the Preventing and Controlling Infections Standard, health service organisations must ensure that reprocessing of reusable medical devices follows current standards and manufacturers’ instructions. Accreditation for hospitals and day surgery centers now explicitly checks that facilities have: (1) reprocessing procedures consistent with national/international standards, (2) a traceability system to track instruments to patients/procedures, and (3) processes to plan and manage reprocessing including for emerging infection risks. This means that a hospital or clinic must demonstrate that its sterilisation methods such as steam, ETO, plasma, etc. are validated and operated according to AS 5369 and any equivalent benchmarks, and that they can trace each critical device load to a patient in case of a recall.

AS 5369:2023 itself lays out detailed requirements on all aspects of reprocessing. This includes facility design e.g. separation of clean and dirty areas, air flow, equipment performance qualification and validation e.g. commissioning tests for sterilisers, routine efficacy monitoring, staff training and credentialing, infection control practices, packaging and storage of sterile items, and maintenance of records. Important compliance points are:

Validation and Routine Monitoring: Sterilisers must be tested to ensure they achieve parameters. Steam sterilisers, for example, need periodic calibration and daily air-removal tests; low-temp sterilisers often require biological indicator tests at defined intervals. AS 5369 insists on documenting these validation results and routine indicators as proof of sterility assurance. A clinic must have a policy for how it uses chemical indicators, biological spore tests, and Bowie-Dick tests, etc., in line with the standard’s recommendations.

Load Traceability: Especially for critical items entering sterile body sites, each item or set should be traceable. Commonly, this is done via batch labels on packs that get logged to patient records. For instance, a sterilisation load number or barcode is placed on each instrument pack, and after a surgery, that number is recorded in the patient’s file along with the instrument description. If later a sterilisation failure is discovered or a product recall happens, the facility can identify which patients might be affected. AS 5369 strengthens these requirements, expecting even small office practices to implement some form of traceability for critical and semi-critical devices.

Manufacturer’s Instructions: Compliance also means following device-specific reprocessing instructions. The standards reiterate that if a manufacturer says an item must be sterilised by ETO only for example, then the facility must either have that capability or not use that item on multiple patients. Reusable medical devices should come with reprocessing IFUs, and surveyors will check that the facility adheres to those e.g. not running a device in plasma if the IFU forbids it.

Water Quality and Utilities: The standards address utilities for steam sterilisation, water purity for steam generation and final rinsing of disinfectors must meet certain specs to avoid spotting and microbial load. AS 5369:2023 includes updated requirements for water treatment and regular water quality monitoring in sterilisation departments. Facilities are expected to conduct a risk assessment and ensure their water or the water produced by onsite filtration systems meets the needed quality for instrument reprocessing for both steam generation and washing.

Environmental controls and Occupational Safety: Compliance includes having appropriate ventilation e.g. dedicated exhaust for ETO or formaldehyde if used and monitoring of staff exposure if handling toxic sterilants. Standards and regulators like Safe Work Australia require that any use of hazardous gases is controlled. An example is ensuring an ETO steriliser has an interlock and venting so staff are never exposed to raw ETO >1 ppm, and having emergency protocols for spills or leaks. The new standard and NSQHS actions push for regular risk assessments and mitigation for such hazards.

Crucially, the Australian Commission on Safety and Quality in Health Care has removed fixed deadlines for compliance with AS 5369, instead requiring a risk-managed transition. They issued Advisory AS24/01 (Nov 2024) instructing health service organisations to perform a gap analysis by 30 June 2025 comparing their current practices against AS 5369:2023. Organisations must then implement an action plan to address any gaps, focusing first on high-risk issues. There is an expectation that over time all facilities will “work towards full compliance” with the latest standards. Accrediting agencies will check that a plan is in place and being actioned. This approach acknowledges that some facilities, especially smaller clinics or aged care facilities might need time and resources to upgrade practices for example, to purchase a compliant washer-disinfector or to modify storage areas to meet new humidity controls. The emphasis is on continuous improvement and risk mitigation: if something isn’t yet compliant, the facility should have interim safety measures and a timeline to comply.

For specialised clinics like day surgeries, dental practices, and nursing homes, compliance historically fell under AS/NZS 4815, which was somewhat tailored to office practices e.g. dental offices sterilising their instruments. Now with AS 5369, those smaller settings are held to essentially the same reprocessing principles as hospitals. Dental and GP clinics are often subject to separate accreditation e.g. through bodies like QIP or ADA’s accreditation scheme which incorporate these standards by reference. Additionally, state health departments and professional boards like the Dental Board of Australia’s guidelines on infection control also require adherence to prevailing standards. This means a dental clinic must ensure its benchtop autoclave is routinely validated such as spore tested, etc., that logs are kept, and that instruments are packaged and stored correctly. A day surgery center must have a sterilisation room that meets layout requirements and documented training for its sterilisation techs. Nursing homes, which are regulated by the Aged Care Quality Standards, are now also encouraged to follow AS 5369 for any reuse of medical devices such as podiatry or wound care instruments. There has been some confusion in sectors like aged care about enforcement, but best practice is clear: if you reprocess reusable instruments, you should align with AS 5369 to ensure resident safety and reduce infection risks.

In summary, compliance in Australia is all about aligning with the national standard and demonstrating that through documentation and practice. With the new AS 5369:2023, clinics and hospitals need to update their policies and possibly equipment to meet any new requirements (for instance, improved tracking of instruments, ensuring all steriliser process parameters are routinely audited, or upgrading to sterilisers that have the appropriate cycle types). The regulatory environment via NSQHS for hospitals and other bodies for clinics is increasingly stringent, failing to properly sterilise instruments or to maintain steriliser performance can lead to accreditation issues or even regulatory action. Fortunately, resources like the updated Australian Infection Control Guidelines and various state directives exist to help facilities interpret and implement the standards. The key message is “do it by the book”: whether using steam or low-temperature methods, clinics must follow evidence-based protocols, keep excellent records, and regularly train and audit their staff to remain in compliance.

Cost Considerations

When comparing steam and low-temperature sterilisation, cost is a major factor in decision-making. Costs can be broken down into several categories: capital equipment costs, operational running costs, instrument lifecycle costs, and indirect costs related to workflow. Each sterilisation modality has a different cost profile that clinics must consider alongside performance.

Capital and Installation Costs: Steam autoclaves, especially large hospital-grade ones, can be expensive but generally less costly than advanced low-temp systems. A large steam steriliser might cost on the order of tens of thousands of dollars, plus installation of plumbing, ventilation, and possibly building works. A small tabletop autoclave for a clinic is much cheaper (a few thousand dollars). By contrast, hydrogen peroxide plasma sterilisers and ozone sterilisers tend to have high upfront costs, often significantly more than an equivalently sized steam unit due to their sophisticated technology. For example, an H2O2 plasma steriliser unit might cost well over AUD $100,000 new, and ozone sterilisers similarly carry a high price tag, whereas a medium-size steam steriliser might be a fraction of that. ETO sterilisers are not commonly purchased new by small facilities nowadays; if needed, the service might be outsourced rather than buying an ETO unit, because the installation ventilation, abatement systems and compliance costs are considerable. In summary, steam wins on capital cost in most cases, with the exception of very small autoclaves vs. very small plasma units tabletop plasma units exist but still, their consumable costs make them pricier over time.

Consumable and Cycle Costs: Steam sterilisation uses minimal consumables mainly electricity and water. Water especially if deionised and electricity do incur cost, and high-throughput autoclaves can consume a lot of both with associated utility bills. A study in the UK found the energy and water usage for steam sterilising reusable instrument sets contributes significantly to their carbon footprint and cost. However, in pure dollar terms per cycle, steam is still cheap. There may be costs for boiler chemicals or filter replacements, but per cycle it’s often just a few cents for water and some cents for electricity, plus the cost of disposable wraps or pouches. Low-temp methods have higher consumable costs per cycle. As mentioned, a single plasma steriliser cycle requires a proprietary peroxide cartridge that costs around AUD $10 to $12. Ozone sterilisation uses only oxygen and water, so its direct consumable cost is very low on the order of ~$1 or less in utilities per cycle. ETO consumables (gas cartridges) can be relatively pricey, each single-dose ETO cartridge might cost $20 to $30, and there are also costs for the required CO2 or other diluents if used. Moreover, every ETO cycle typically requires single-use chemical indicator integrators and dosimeters specific to ETO, adding a few dollars, and the long runtime means using electricity for many hours. When comparing just the sterilant cost: steam is lowest, ozone is next since it makes its sterilant from air/water, plasma is higher, and ETO often the highest. One study historically compared the cost per sterilisation of different methods and found ETO to be the most expensive procedure, followed by hydrogen peroxide plasma, with steam sterilisation being the cheapest method on a per-load basis. Formaldehyde LTSF was noted to have relatively low direct costs (formalin is inexpensive), though that method’s other drawbacks often outweigh cost benefits.

Maintenance and Compliance Costs: All sterilisers require maintenance, yearly preventive maintenance, calibration, part replacements like door gaskets, filters, vacuum pumps etc. Steam autoclaves can be maintenance-heavy such as gaskets and heaters wear out, valves need tuning. Low-temp units also have maintenance costs, plasma generators or ozone destruct units require servicing. It’s hard to generalize which costs more; service contracts for a plasma steriliser can be high due to expensive parts, whereas a steam autoclave’s maintenance might be simpler, but more frequent if heavily used. Additionally, compliance adds costs: for instance, biological indicators for plasma or ETO are more expensive per test than for steam. A facility might need to incubate spore tests so possibly buy an incubator and keep chemical indicators in stock for each method. If using ETO, there are costs related to worker safety like badges for gas monitoring, ventilation system upkeep, licensing fees if any. These must be factored into the total cost of ownership. A manufacturer analysis suggests calculating total cost of ownership as purchase cost + running cost + cost of downtime when the steriliser is not available. For plasma sterilisers, downtime or throughput limits due to the small chamber might mean needing multiple units to handle load, which multiplies capital cost.

Instrument Replacement and Damage Costs: An often hidden cost is the impact of sterilisation method on instrument longevity. Using an inappropriate method can ruin instruments, leading to expensive replacements. For example, if a delicate endoscope or power tool is accidentally autoclaved, it could be a write-off of tens of thousands of dollars. Even when using the correct method, repeated high-heat steam cycles can wear out certain instruments faster, e.g. rigid endoscopes and camera lenses may get foggy or misaligned after numerous steamings, and plastic components can degrade. One comparative study found that although steam was cheapest per cycle, when factoring in damage to sensitive instruments like an optical vitrectomy probe, the cost of plasma sterilisation became nearly equivalent to steam because plasma caused significantly less device damage over time. In other words, investing in a gentler low-temp process can extend the life of costly instruments, offsetting its higher running cost. ETO is very gentle on instruments (no heat at all), so instrument damage is minimal, its costs are elsewhere (time and safety). Hydrogen peroxide is also gentle, though repeated exposure might slightly dull certain coatings or electronics have a finite life regardless. In contrast, steam’s harsh conditions might dull fine cutting instruments or necessitate more frequent repairs/replacements e.g. sharpening of scissors, replacement of fiber-optic light cords, etc.. Clinics should weigh the cost of an instrument inventory: if most instruments are sturdy and cheap e.g. stainless steel tools, steam’s impact is negligible; but if you have many fragile or expensive devices, a low-temp method could reduce repair and replacement expenses.

Throughput and Productivity Costs: The speed of a sterilisation method affects how many instrument sets a facility must own and how quickly cases can be turned over. Steam’s quick cycles mean fewer sets may be needed, you can sterilise and reuse the same instruments multiple times a day. This is cost-efficient for high-volume use. Slow methods like ETO or ozone impose inventory costs: because items are out of commission for many hours, you might need 2 to 3 duplicate sets to ensure one is always available while others are in sterilisation or aeration. Buying extra instrument sets is a significant cost for example, having three sets of a specialty instrument that costs $5,000 each, just to accommodate a slow sterilisation turnaround. One economic analysis concluded that when considering the time element, the faster cycle of plasma sterilisation can yield cost savings by reducing the need for duplicate instruments. Specifically, plasma (cycle ~45 min) vs ETO (cycle ~12+ hours): a hospital could save by not having to buy as many backup endoscopes, because plasma allows the same scope to be sterilised between patients in under an hour, whereas ETO would tie it up for a full day. Thus, time is money in sterilisation: slow methods carry an “opportunity cost” in instrument utilization. Day surgeries and busy operating theaters highly value quick turnaround, a delay in instrument availability can mean delayed or cancelled procedures, which is very costly in terms of staff and patient scheduling. In such cases, the higher per-cycle cost of plasma might be justified by the throughput advantage.

Outsourcing vs In-House Costs: For clinics with low volume or very occasional need for low-temp sterilisation, outsourcing may be more cost-effective than owning a seldom-used machine. For example, a small ophthalmology clinic that mostly uses steam, but once a month needs to sterilise a heat-sensitive piece of equipment, might make arrangements with a nearby hospital to run it in their plasma steriliser perhaps for a fee rather than investing $100k in their own unit that mostly sits idle. Similarly, some dental practices send certain items out to specialist reprocessors though most dental tools are steam-tolerant. Outsourcing shifts cost to a per-use fee, which can be cheaper than ownership if usage is sparse. The trade-off is scheduling and transport logistics, and trusting the external provider’s quality. Some clinics instead choose to use single-use disposable instruments for tasks they can’t reprocess in-house. This can be cost-effective if those tasks are rare. But reliance on disposables for complex instruments can become very expensive if used frequently, and generates biohazard waste. There is a balance to find: beyond a certain volume of use, investing in the reusables and proper sterilisation may be cheaper in the long run and environmentally friendlier. Indeed, a 2017 economic analysis in Australia suggested that for large healthcare facilities, investing in low-temperature sterilisation systems was likely a good decision financially, considering the benefits of reprocessing delicate instruments in-house. Larger facilities can spread the capital cost over many cycles and save by reusing instruments rather than constantly buying disposables or paying outsourcing fees.

In plain terms, steam sterilisation is generally the most cost-efficient method when the instruments can tolerate it, it has low running costs and high throughput, which means cost per instrument use is very low. Low-temperature methods come with higher costs per cycle and often higher capital costs, but they are necessary for certain instruments and can be justified by preventing instrument damage and enabling procedures that wouldn’t be possible otherwise. Decision makers should conduct a cost analysis considering their facility’s case mix: If a hospital has dozens of heat-sensitive flexible endoscopes with infection risk, not having a low-temp steriliser could result in expensive infections or device degradation. Here the cost of the machine is outweighed by clinical benefit and risk reduction. On the other hand, if a small clinic rarely needs low-temp, they might avoid that cost by other means.

To optimise costs, facilities often maximise the use of steam since it’s cheap and fast and use low-temp only where indispensable. Additionally, practices like loading sterilisers to capacity running full loads rather than half-empty improve cost efficiency per instrument. Another strategy is using reusable sterilisation containers in steam processes to reduce recurring wrap costs as these containers cost upfront but save money over time and reduce waste. For low-temp processes, manufacturers sometimes offer bulk pricing on consumables or different cycle options e.g. short cycles that use less sterilant if the load is small to manage costs. All these factors feed into the total cost of running a sterile processing department.

In conclusion on cost: A clinic must weigh the economics of sterilisation holistically, considering equipment purchase, upkeep, consumables, instrument inventory, and the cost of any adverse outcomes like infections or instrument loss. Often a mix of steam and one low-temp modality provides the best balance of patient safety and cost-effectiveness: steam handles the bulk cheaply, and the low-temp device, while costly per cycle, prevents the far greater expense of instrument damage or infection that could occur if one tried to force everything through steam or use suboptimal methods.

Environmental and Safety Considerations

Sterilisation methods also differ in their impact on staff safety and the environment. Modern healthcare management aims to minimise any harmful exposures and reduce the ecological footprint of sterilisation processes, without compromising infection control. Below we compare steam and low-temp methods from these perspectives:

Occupational Health and Safety: From a worker and patient safety standpoint, steam sterilisation is very safe. It uses only water and heat, producing no toxic residues on instruments. Staff and patients are not exposed to any harmful chemicals from a steam-sterilised device. The primary safety concerns with steam are physical: the potential for burns or scalds when unloading hot autoclaves or a sudden release of steam if a chamber is opened improperly. Autoclaves have engineering controls e.g. safety locks that prevent opening under pressure to mitigate this. As long as staff use heat-resistant gloves and follow protocol allowing a cooling-off period, the risks are low. Steam is also safe for the environment, it vents water vapor. There is no chemical waste aside from neutral pH water that may go down the drain from the vacuum system.

Ethylene Oxide, conversely, poses significant safety hazards. ETO is toxic, carcinogenic, and flammable. Chronic exposure has been linked to cancers and reproductive issues, and acute exposure can irritate eyes, lungs, and cause neurological effects. For this reason, facilities using ETO must have robust safety measures: gas-proof chamber seals, external ventilation, detection alarms for leaks, and strict procedures for cartridge handling. Staff may need periodic health monitoring if working with ETO regularly. Because of these issues, ETO use has been greatly limited; many smaller clinics eliminated ETO sterilisation altogether to protect staff and avoid complex regulations. In terms of patient safety, an ETO-sterilised item is safe only if aerated properly, residual ETO on an instrument could be harmful to a patient causing burns or systemic toxicity. That is why the long aeration is mandatory, and why compliance with ETO protocols is absolutely critical. Environmentally, ETO contributes volatile organic compounds (VOCs) to the atmosphere if released. Most machines now capture 99.9% of ETO and break it down, but any emitted ETO is a pollutant and also a greenhouse gas contributor when combusted to CO2. Some regions like certain U.S. states have tightened emissions rules due to ETO from sterilisation facilities potentially elevating local cancer risk. Australia likely requires similar controls under its environmental and work safety frameworks.

Hydrogen Peroxide Gas Plasma is generally considered environmentally and worker-friendly. H2O2 is not a listed carcinogen; it can be irritating or corrosive at high concentrations, but plasma steriliser designs keep it contained. After the cycle, the peroxide is converted mostly to oxygen and water, no toxic residuals remain on instruments. Staff do not need special respiratory protection when operating these units beyond normal PPE for handling sterile packs. As a precaution, if a cycle aborts mid-way, staff might need to vent the chamber in a fume hood or allow time for peroxide to dissipate, but such incidents are infrequent. The machines often have sensors to ensure no peroxide is present before unlocking. For patients, there’s no risk of residue, any traces of peroxide quickly break down and are non-toxic, a far cry from ETO which could harm tissues if not removed. Environmentally, the by-products (water and oxygen) are benign. The manufacturing and disposal of the single-use peroxide cartridges is a minor environmental consideration such as plastic waste and energy to produce peroxide, but overall, peroxide sterilisation is clean and often touted as a “green” alternative to ETO. One point: hydrogen peroxide sterilisation does use electricity for vacuums and plasma generation, which has a carbon footprint depending on the power source. But it typically uses less energy per cycle than running a large steam autoclave, especially if the steam steriliser is tied to an energy-intensive boiler.

Ozone sterilisation similarly has a favorable safety/environmental profile in output: ozone is a toxic gas if inhaled, but the steriliser ensures none is released to the room (converting it back to oxygen). As long as the system is functioning correctly, staff are not exposed. There is no chemical residue on instruments, any ozone has decomposed to oxygen by cycle end. If an ozone leak did occur, it would smell pungent and could irritate respiratory passages, but such events are rare and machines have monitoring systems. Ozone is also short-lived half-life in air of about 30 minutes, so any small escaped volume dissipates. For patients, ozone leaves no residue to worry about. Environmental impact of ozone sterilisation is minimal: it doesn’t create persistent pollutants. The process does produce oxygen-rich exhaust and some humidity. Ozone itself is a greenhouse gas in the upper atmosphere and a pollutant at ground level, but since the steriliser catalytically destroys it, it doesn’t contribute to smog or ozone-layer issues. The main environmental footprint is electricity use and the production of any consumables like if it uses an ozone catalyst that has to be changed occasionally, or O2 tanks which have manufacturing and transport impacts.

Formaldehyde (LTSF), like ETO, has safety downsides. Formaldehyde is classified as a carcinogen and can cause severe irritation and allergic reactions. Staff must avoid breathing any fumes, sterilisers are sealed and typically have purge cycles to eliminate formaldehyde before opening, often using ammonia filters or just prolonged aeration. Despite these measures, many steriliser operators have moved away from formaldehyde partly due to the smell and health concerns. Any accidental exposure e.g. a leak or if someone opened a chamber too soon could cause burning of the eyes, throat, or asthma-like symptoms. In terms of residue, formaldehyde can leave a residue on instruments (a sticky paraformaldehyde deposit) if not properly flushed, this could be toxic or at least irritant to patients and damaging to instruments. Good machines ensure minimal residue, but it’s another thing to monitor. Environmentally, formaldehyde in the atmosphere breaks down relatively quickly in a couple of hours, so it doesn’t persist, but releasing it indoors or in large quantities is obviously undesirable. Waste formalin solutions if any have to be treated as chemical waste.

Worker Ergonomics and Stress: Another safety aspect is the workload and ergonomics associated with each method. Steam sterilisation of large instrument trays can be physically demanding, heavy trays and carts, hot surfaces, etc. Staff need training in proper lifting techniques and use of loading trolleys. Low-temp methods often handle smaller loads since many heat-sensitive devices are smaller, which can be easier physically, though frequent loading of a small plasma unit can be repetitive. Also, the higher complexity of low-temp devices means staff must be vigilant about instructions and troubleshooting alarms, which can be a cognitive load. Ensuring adequate staffing and training helps reduce human error, a safety concern itself, since an error in sterilisation can lead to non-sterile instruments in surgery.

Environmental Footprint and Sustainability: Hospitals are increasingly mindful of the environmental impact of reprocessing. Energy consumption is significant for steam sterilisers: they require heating to high temperatures and often run continuously during the day. If the electricity comes from fossil fuels, this translates into carbon emissions. Water usage in steam sterilisation can also be high and older autoclaves might use dozens of liters per cycle for steam generation and vacuum pump cooling. Some newer models recirculate water or use dry vacuum pumps to reduce this. By contrast, low-temp systems usually use less electricity per cycle, no need to maintain extreme heat for long periods, though plasma systems have vacuum pumps and RF generators that use moderate power. A British Journal of Surgery study (Rizan et al. 2022) estimated the carbon footprint of steam sterilising surgical instrument sets and found it contributed substantially to the overall environmental cost of using reusables, especially due to energy and single-use packaging. They noted that optimizing steriliser loading and using lower-carbon energy sources can improve sustainability.

Waste generation is another factor: Sterilisation processes generate waste mainly in the form of used packaging (paper or plastic pouches, indicator strips) and consumable cartridges or filters. Steam sterilisation often uses paper-based packaging that is single-use and then discarded. Low-temp methods use synthetic packaging (also single-use) and things like plastic chemical indicator strips, chemical cartridges (peroxide cassette shells), etc. All these add to clinical waste. Reusable hard cases for steam can mitigate wrap waste; similarly, some plasma sterilisers allow reusable instrument containers with special filters, which could reduce pouch waste though those filters themselves must be replaced eventually.

Chemical waste: ETO cartridges after use are considered hazardous waste until aerated out, they must be disposed of properly. Formaldehyde absorbents or expired formalin ampoules also become hazardous waste. In plasma sterilisation, the used cassette might have minimal peroxide left, typically it’s exhausted and can be disposed of as regular waste. Some manufacturers say the empty cassette is non-hazardous. Ozone sterilisation doesn’t produce a waste product except perhaps some filters that get changed infrequently.

Regulatory trends: Environmental regulations are pushing sterilisation technology to be cleaner. As mentioned, ETO emissions are tightly controlled, any facility using ETO must have nearly complete capture of the gas. Some countries are even looking to phase down ETO use because of emissions concerns. This regulatory pressure indirectly encourages adoption of alternatives like hydrogen peroxide, vaporised peracetic acid, or gamma irradiation for industrial sterilisation of single-use items which don’t have the same emissions issues. Australia follows international best practices here, requiring ETO use to be justified and well-controlled. From a worker safety angle, Work Health and Safety (WHS) regulations require risk assessments for any hazardous chemical use in a workplace, thus a clinic using formaldehyde or ETO must have documented risk controls like fume hoods, exposure monitoring, staff training and health surveillance. Failure to do so could lead to penalties.

Patient safety and infection prevention: It’s important to note that while we consider environmental impact, the priority is effective sterilisation. A slight increase in waste or energy use may be justified if it enables a higher level of patient safety for example, using robust disposable packaging to ensure sterility maintenance. Reusable medical devices themselves are part of environmental sustainability by avoiding the waste of single-use devices, but they only yield benefit if reprocessed safely. An unsterile instrument leading to infection has an enormous human and financial cost. Therefore, sterilisation choices try to strike a balance between being safe for people and gentler on the planet. Increasingly, manufacturers design sterilisers with eco-features such as energy-saving modes, water recycling, lower temperature cycles for partial loads, etc. and even explore new sterilants like nitrogen dioxide or cold plasma sterilisation that might have less resource usage.

Summary of Safety/Environmental Pros & Cons: Steam: Pros: Nontoxic, no chemical residues (safe for patients/staff), relatively simple waste (mostly water). Cons: High energy and water consumption; hot effluent can heat up work areas; risk of heat injury to staff if not careful.

Hydrogen Peroxide Plasma: Pros: No toxic emissions (by-products water and oxygen), safe for staff (closed system), no residue on instruments. Cons: Requires manufacturing and disposal of chemical cartridges; cannot process biodegradable materials so some sustainable packaging can’t be used; moderate electricity use; H2O2 vapor in high concentration is hazardous but contained during normal operation and are a slight risk if a leak occurs, which is rare.

ETO: Pros: Very versatile sterilant. Cons: Hazardous substance, toxic, carcinogenic, flammable; stringent controls needed; residual gas needs removal; contributes to greenhouse gases (via CO2 conversion) and harmful emissions if not fully captured. From an environmental view, ETO is the least favored nowadays due to these reasons.

Ozone: Pros: Generated on-site from O2, so no transport or storage of hazardous chemicals; no harmful residue; minimal waste except perhaps filters. Cons: Ozone gas is toxic if released; systems must ensure full conversion to oxygen, which they generally do; uses electricity and water; cannot use cotton or paper, so has some overlap with plasma in needing synthetic materials. Overall, ozone is quite green if properly managed.

Formaldehyde (LTSF): Pros: Effective at moderate heat; formaldehyde breaks down naturally. Cons: Noxious and dangerous to staff; strong irritant; public and occupational safety concerns make it an undesirable choice environmentally and for worker health.

Healthcare facilities are increasingly adopting the “Green Sterilisation” concept: aiming to reduce waste, e.g. using larger steriliser loads, opting for reusables over disposables when safe, recycling materials when possible, reduce energy/water usage e.g. by upgrading to energy-efficient sterilisers, using load sensors, etc, and phasing out the most hazardous chemicals in favor of safer alternatives. For instance, many Australian hospitals have eliminated on-site ETO partly for these reasons, relying on H2O2 plasma or outsourced gamma irradiation for items that previously might have been ETO-sterilised.

In conclusion, steam sterilisation has an excellent safety profile for people but an environmental cost in resource usage, whereas low-temperature methods vary: modern processes like H2O2 and ozone are designed to be safe and eco-friendly in terms of outputs, while older chemical methods (ETO, formaldehyde) pose health hazards and require careful management. Decision makers should ensure that whichever methods are used, engineering controls and work practices protect staff (no exposure to hot surfaces or toxic fumes) and that any environmental regulations for emissions, waste disposal are met or exceeded. By staying informed about new technologies like low-temp steriliser models that use less energy or novel sterilants and maintaining equipment well, clinics can both safeguard their personnel and reduce their sterilisation carbon footprint over time.

Implementation in Different Healthcare Settings

The choice and balance of steam vs low-temperature sterilisation in specialised clinics often depends on the nature of procedures, the types of instruments used, and the scale of the facility. Below, we consider how these methods are typically implemented across various Australian healthcare settings:

Large Hospitals CSSD (Central Sterilising Services Department): Steam sterilisation is the backbone of instrument reprocessing in hospitals. A busy hospital CSSD will have multiple large steam autoclaves running all day to process surgical trays, linens, gown packs, etc. Steam handles the majority >90% of surgical instruments, which are mostly metal and heat-stable. Low-temperature sterilisers are used as an adjunct for specific needs, for example, a tertiary hospital might have one or two hydrogen peroxide plasma steriliser units in the CSSD for all the items that cannot go through steam flexible endoscopes, cameras, power drills that can’t be autoclaved, delicate plastic items, etc. Some hospitals also maintain an ETO steriliser or contract out ETO for extremely heat-sensitive items that plasma can’t accommodate like long multi-channel endoscopes, or equipment with cellulose components. In general, hospitals try to minimise ETO use due to its drawbacks. Ozone sterilisers are not yet common, but a large hospital might consider ozone or vaporised peracetic acid systems if they have a high volume of devices incompatible with both steam and plasma. Workflow: Hospitals have dedicated staff for each area; e.g. one team loads steam autoclaves, another handles the low-temp machines, ensuring no mix-ups. They maintain compliance through rigorous policies, every load is monitored, and instruments are tracked often via barcode systems to each patient. Hospitals also typically have redundancy if one steriliser is down, others can cover the load, which is critical for patient care continuity. In sum, hospitals use a hybrid approach: steam for efficiency and cost-effectiveness, low-temp for preserving expensive instruments and enabling advanced medical procedures, all under strict compliance oversight.

Day Surgery Centres and Specialty Clinics: Day surgeries (stand-alone surgical centers) perform invasive procedures on a smaller scale than hospitals. They typically have at least one or two steam sterilisers, often medium-sized floor models or large tabletop models to reprocess surgical sets during the day. Steam is favored for its quick turnaround which aligns with tight surgery schedules e.g. a cataract surgery center can autoclave instrument sets between patient cases. Many day surgeries limit their equipment selection to mostly steam-compatible instruments to avoid complexities. However, certain specialties necessitate low-temp use. For instance, an ophthalmic surgery center might have delicate microsurgical handpieces or plastic intraocular tool sets that are heat-sensitive. Similarly, an orthopedic day surgery might use power tools or fiber-optic scopes not suited to steam. In such cases, a hydrogen peroxide plasma steriliser is often the choice, it’s practical for a clinic setting no toxic emissions, fast cycle and protects those devices. Nancy Chobin, an expert in sterile processing, noted that in surgery centers ETO is generally not feasible due to its hazards and long cycle, whereas plasma or ozone are the preferred low-temp options if needed. Indeed, a day surgery that invests in low-temp usually goes with plasma or occasionally ozone over ETO. Workflow: These clinics plan their cases so that items requiring low-temp are turned over accordingly, e.g. a flexible scope might be run in a plasma steriliser while other instruments are steamed. Turnaround time is considered; plasma’s ~45 min cycle can fit between cases, whereas ozone’s 4-hour cycle is harder to accommodate unless done overnight. Many day surgeries will avoid acquiring instruments that need ozone’s cycle length. Training is also streamlined, with fewer staff, so each person might handle both steam and plasma sterilisation tasks; clear procedure manuals are followed. Compliance and record-keeping in day surgeries are equally as strict, they are often accredited under NSQHS standards like hospitals, meaning they must show that they meet AS 5369 for sterilisation. Overall, day surgeries tend to maximize use of steam for speed and economy and use low-temp only when essential for device compatibility, ensuring they can still meet surgical schedules and budget constraints.

Dental Clinics and Office-Based Practices: Dental and general practice clinics perform a high volume of instrument reprocessing, but the instruments are usually simple e.g. dental mirrors, forceps, handpieces, surgical drapes and almost always steam-tolerant. Steam sterilisation is the mainstay of dental clinic infection control. Most dental clinics have one or more benchtop autoclaves that run many cycles per day sterilising burs, handpieces, scalers, and other tools between patients. Dental instruments are designed to be autoclaved, modern dental handpieces, for example, are manufactured to survive steam sterilisation at 134 °C, as per infection control guidelines. It’s rare for a dental office to require low-temperature sterilisation; nearly everything can go into a steam steriliser or be high-level disinfected if heat-sensitive e.g. some impression trays or polymer items might be disinfected chemically if they can’t be steamed, or simply disposed of if single-use. Operationally, dental assistants manage instrument turnover such that while one set is being used on a patient, another set is in the autoclave and another cooling, etc. Because benchtop autoclaves have relatively short cycles, often 15 to 30 min plus cool down, they support the dental workflow well. Dental practices adhere to Australian Dental Association (ADA) and Dental Board guidelines which align with AS 5369 requiring regular validation of autoclaves such as spore tests, calibration and documentation of each cycle. Dental offices seldom invest in expensive low-temp equipment; if a specialized instrument needed gas sterilisation, they might send it to a hospital or simply choose a single-use version of that instrument. With the advent of things like 3D-printed dental guides and certain implant components, if any of those cannot be autoclaved, typically they are provided sterile or single-use. Thus, for dental clinics, steam is the efficient, low-cost solution and the infrastructure needs such as power outlet and distilled water supply are straightforward. Staff are trained in loading pouches correctly to allow steam penetration and in storing sterile packs properly often in closed cabinets with date labels as per standards. Compliance in dentistry is monitored through practice inspections, a clinic must show they maintain their sterilisers and follow proper wrapping, storage, and traceability e.g. keeping a log of each cycle and the contents/load number.

Nursing Homes and Aged Care Facilities: Nursing homes provide clinical care but typically not surgical procedures. Their need for sterilisation is limited to a few use cases: podiatry or foot care instruments for example nail clippers, podiatric burrs, some wound care or minor surgical kits for on-site wound dressing changes or skin lesion removals by visiting GPs, and possibly reusable continence care items or dentures. Many aged care facilities in Australia have moved towards disposable single-use items for infection control simplicity e.g. single-use podiatry kits, disposable razors, etc, especially after the tightening of reprocessing standards. However, some larger homes or those co-located with health services do have a small sterilisation setup. Steam sterilisation (small autoclave) would be the method of choice for such facilities, given the low volume and relatively basic instruments. For example, a nursing home might have a benchtop autoclave to sterilise a set of podiatry instruments used by a visiting podiatrist, rather than sending them out. Low-temperature sterilisation is generally not used on-site in aged care, because they typically do not own extremely delicate surgical instruments. If they had something like a flexible endoscope for a medical procedure, they would likely rely on a visiting service or send it to a hospital for reprocessing. Additionally, aged care facilities are not under the same acute-care accreditation, and historically some struggled to meet AS 4187 due to resource constraints. The introduction of AS 5369 means aged care is now explicitly within scope, but the Aged Care Quality and Safety Commission is working out how to enforce or encourage compliance. In practice, many aged care facilities opt to outsource sterilisation needs or use single-use devices to avoid reprocessing altogether, focusing internal efforts on cleaning and disinfection processes for environmental hygiene. If a facility does reprocess, they must follow the standard, for example, one aged care home might partner with a nearby hospital to sterilise their equipment, or have an implementation plan to upgrade their steriliser and training by a certain date. Cost and logistic considerations are critical: it may be cheaper and safer for a low-volume user like a nursing home to outsource to a central sterile service than to maintain their own full compliance sterilisation program.

Specialist Medical Offices e.g. Dermatology, Plastic Surgery clinics: These clinics often do minor surgical procedures such as skin lesion excisions and biopsies and use reusable instrument sets like scalpels and forceps. Like dental clinics, nearly all their tools can be steam sterilised in a tabletop autoclave. They’ll run cycles maybe a few times a week or daily depending on patient load. They rarely need low-temp methods; if a device like a laser handpiece or an ultrasound probe is used, those are typically high-level disinfected or have manufacturer-prescribed cleaning not sterilised between patients as they might be non-critical or semicritical devices. Only if a clinic uses an unusual piece of equipment that can’t be autoclaved, perhaps a delicate camera used in ENT examinations would they contemplate low-temp, and even then, many would coordinate with a larger facility to handle it.

In essence, steam sterilisation is ubiquitous across all settings for any instrument that can tolerate it, due to its low cost and simplicity. Low temperature sterilisation is employed more selectively, primarily in hospitals and day surgeries where advanced surgical instruments are used. In smaller clinics, low-temp methods are uncommon on-site; those clinics either find alternatives or rely on external services. Each setting must still abide by core principles: cleaning instruments thoroughly, packaging and processing them correctly, and storing them to maintain sterility until use. The extent of complexity and thus the need for costly low-temp gear usually rises with the complexity of care: a big hospital doing cardiothoracic surgery will need things a day surgery doing cataracts will not; the day surgery might still need more than a family dental practice, and so on.

Decision-makers in each setting should evaluate: What instruments do we reprocess? Can they all be steam-sterilised? If not, how frequently do we use those that can’t? This will guide whether purchasing a low-temp steriliser is justified. For example, if a day surgery finds that only one type of catheter they use cannot be autoclaved, it might be cheaper to switch to a single-use version of that catheter rather than buying a gas steriliser just for it. Conversely, if a clinic is expanding services to include lots of endoscopy, it may need to invest in appropriate sterilisation or high-level disinfection equipment. The aim is to ensure patient safety by proper sterilisation without undue delay or risk and different settings strike that balance differently. The new standards unify the expectations, but the practical implementation will scale to the facility’s scope of practice.

Conclusion and Recommendations

Both steam and low-temperature sterilisation are indispensable in modern healthcare, each with its own strengths and limitations. Steam sterilisation should be used whenever possible on instruments that can withstand it, given its superior efficiency, low cost per cycle, and well-proven microbicidal power. Steam is the backbone of sterilisation in hospitals, day surgeries, and clinics, it allows rapid turnaround of critical instruments and is straightforward to operate and monitor. All clinics are encouraged to invest in adequate steam sterilisation capacity with properly maintained autoclaves and training as the primary means of achieving sterilisation for general instruments.

However, advanced medical care increasingly relies on devices that are heat-sensitive or electronics-laden, which necessitates low-temperature sterilisation methods. These methods, notably hydrogen peroxide gas plasma, and to a lesser extent ozone or ETO enable safe reprocessing of complex and delicate equipment that steam would damage. Adopting a low-temp sterilisation modality is essential for facilities using flexible endoscopes, certain minimally invasive surgical tools, implantable sensor devices, or other high-tech instruments. For large hospitals, the evidence suggests that investing in low-temperature sterilisation capability is not only clinically necessary but can be economically wise in the long run. It prevents the need for disposable instruments which may be very costly, extends the life of expensive equipment by avoiding heat damage, and ensures a higher standard of infection control for all device types. Large facilities often deploy multiple sterilisation technologies to cover all bases, and this multi-modal approach is recommended for any center that handles a wide variety of surgical devices.

Compliance with standards and best practices is non-negotiable, sterilisation is a critical patient safety function. Australian clinics and hospitals must align with AS 5369:2023 and related guidelines. This means: validating every load, using chemical/biological indicators appropriately, logging and tracking instruments to patients, and continuously training staff in the latest protocols. Decision-makers whether a hospital CEO or a dental clinic owner should ensure resources are allocated for staff education in sterilisation, because even the best equipment can fail if misused. Regular audits and maintenance are also key: a slightly malfunctional steriliser can put patients at risk, so preventive upkeep and immediate correction of any process failures are vital parts of the sterilisation program.

In making choices between or optimising steam vs low-temp use, consider the following recommendations:

• Maximise Use of Steam for Routine Items: Steam is fastest and most cost-effective for durable surgical sets, so use it for all instruments that tolerate high temperature. This frees up low-temp devices for only the items that truly need them, optimising workflow and cost.
• Select Low-Temp Technology Based on Your Device Profile: If the facility mostly needs to reprocess flexible endoscopes or delicate scopes, a hydrogen peroxide plasma steriliser is a good choice as it is fast and compatible with most scopes, aside from very long lumen ones. If the facility has a lot of long narrow lumen devices that plasma can’t cover, consider ozone sterilisation or ETO with a strong preference to ozone if cycle time can be managed, given safety. For small clinics, plasma sterilisation is often the practical low-temp choice since it’s easy to manage and safer than ETO.
• Outsource or Share Services When Feasible: Smaller clinics that only occasionally need low-temp sterilisation should evaluate partnering with larger hospitals or specialised reprocessing services. For example, a day surgery could send a rare item to a tertiary hospital’s CSSD for gas sterilisation via a formal agreement. This avoids the clinic having to maintain seldom-used, expensive equipment and keeps focus on their core steam processing. Ensure, however, that any transport of instruments maintains infection control (closed containers) and traceability.
• Consider Instrument Alternatives: Where sterilisation modality is problematic, consider alternative instruments. For instance, if a certain device is not easily sterilised and requires ETO which you don’t have, see if a single-use version is available for those instances, or if a re-usable but steam-sterilisable version exists. The one-time higher cost of a different instrument might pay off by eliminating a whole category of reprocessing complexity.
• Invest in Quality Packaging and Monitoring: Regardless of method, use the best quality packaging materials and indicator systems. A minor cost increase for higher integrity wraps or reliable indicators is worth it for patient safety. Faulty packaging can compromise sterility, for example, low-temp sterilised items need packaging that won’t let in microbes during storage because no high heat was used to kill them at point-of-use. Ensure staff know how to inspect packs and avoid any whose sterility may have been breached such as wet packs, tears, expired storage time, etc.
• Keep Abreast of Technological and Regulatory Changes: Sterilisation technology is continuously evolving, for example, nitrogen dioxide sterilisation or improved low-temp chemistries are emerging. Regulations also update as we saw with AS 5369:2023. Decision-makers should remain informed through resources like the Sterilization Research Advisory Council of Australia (SRACA), infection control conferences, and manufacturer updates. This allows timely upgrades to equipment or processes to stay compliant and efficient. A good practice is performing periodic risk assessments and gap analyses as required by the standards to identify where improvements are needed, for instance, if water quality is an issue affecting steam results, invest in a water purification unit; or if documentation is lacking, perhaps implement a computerised tracking system.

In conclusion, steam and low-temperature sterilisation are complementary tools in infection prevention. Specialised clinics in Australia should leverage steam sterilisation for its reliability and low cost in handling the bulk of instrument reprocessing, while employing low-temperature methods strategically for those items where steam is not suitable. By doing so, clinics can achieve a high level of sterility assurance across all instruments while managing costs and complying with national standards. The overarching goal is the safety of patients and staff: delivering sterile instruments for every procedure, every time. With diligent adherence to guidelines and thoughtful selection of sterilisation modalities, decision-makers can ensure their facilities meet this goal, whether it’s a large metropolitan hospital or a small rural day surgery. Each facility should develop a sterilisation policy that reflects these best practices and regularly review it, fostering a culture where sterilisation is seen not as a behind-the-scenes task but as a critical, quality-controlled process integral to patient care. Steam and low-temp sterilisation, used in tandem, form a complete sterilisation strategy that allows specialised clinics to provide safe, high-quality healthcare in Australia’s diverse clinical environments.

Sources

1. World Health Organization - Decontamination and Reprocessing of Medical Devices for Health-care Facilities (2016)
2. Centers for Disease Control and Prevention - Guideline for Disinfection and Sterilization in Healthcare Facilities (2008, updated)
3. Australian Commission on Safety and Quality in Health Care – Advisory AS24/01 (2024)
4. Outpatient Surgery Magazine (AORN) - “Plasma or Ozone: Which Is Better For You?” by Nancy Chobin (2007)
5. Adler et al., Journal of Hospital Infection 40(2):125-134 (1998): cost comparison study of plasma, ETO, formaldehyde, and steam sterilisation
6. McCreanor & Graves, American Journal of Infection Control 45(7):756-760 (2017)
7. Rizan et al, British Journal of Surgery 109(2):200-210 (2022)
8. Standards Australia - AS 5369:2023 (and formerly AS/NZS 4187:2014)