White Paper

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

October 2026

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 paper compares moist heat (steam) sterilisation with low temperature sterilisation for hospitals, day procedure centres, dental and office-based practices and aged care facilities in Australia. It sets out process parameters, efficacy limits, material compatibility, building services, AS 5369:2023 requirements, cost per cycle, chemical safety controls and process selection by facility type.

Sterilisation Methods Overview

Steam: Moist heat sterilisation uses dry saturated steam. Steam condenses on the load, releases its latent heat and denatures microbial proteins. AS 5369:2023 sets minimum holding times of 15 min at 121 deg C [250 deg F], 10 min at 126 deg C [259 deg F], 4 min at 132 deg C [270 deg F] and 3 min at 134 deg C [273 deg F]. Air removal, heat-up and drying make up most of the cycle, giving an indicative total of 30 to 60 min for a wrapped load in a pre-vacuum steriliser. Steam leaves no chemical residue. It is limited to devices that tolerate the process temperature, pressure and moisture.

Low temperature processes: Used for devices that cannot tolerate moist heat. AS 5369:2023 requires each low temperature system to be tested for efficacy to ISO 14937, to ISO 25424 for low temperature steam and formaldehyde (LTSF) or to ISO 22441 for vaporised hydrogen peroxide (VH2O2), and to be supplied with comprehensive instructions for use (IFU).

VH2O2: Hydrogen peroxide is vaporised under deep vacuum, diffuses through the load and oxidises proteins, lipids and nucleic acids. Some systems add a gas plasma phase that dissociates residual peroxide. Chamber temperature is typically 40 to 55 deg C [104 to 131 deg F]. Indicative cycle time is 25 to 75 min, with lumen cycles at the upper end. Residual peroxide decomposes to water and oxygen, so no separate aeration is required. Cellulose absorbs and decomposes peroxide, so paper, cotton and linen are excluded from the load and packaging.

Ethylene oxide (EO): EO alkylates proteins and nucleic acids. AS 5369:2023 lists common process ranges of 400 to 800 mg/L EO, 37 to 55 deg C [99 to 131 deg F] and 50 % to 90 % relative humidity, with gas dwell time set during performance qualification (PQ). EO diffuses through packaging, polymers and long lumens. Polymers absorb it, so aeration to the residual limits of ISO 10993-7 is required. An indicative build-up is 0.5 to 1 h conditioning, 1 to 4 h exposure and 8 to 12 h in-chamber aeration, about 10 to 17 h in total. Desorption is diffusion controlled, so aeration time increases with polymer wall thickness and EO solubility and decreases as aeration temperature rises.

LTSF: Formaldehyde is admitted with sub-atmospheric steam, typically at 60 to 80 deg C [140 to 176 deg F]. Devices must tolerate this temperature and moisture. Desorption phases remove formaldehyde before the chamber opens.

Other processes: Liquid chemical sterilisation, e.g. peracetic acid, processes unwrapped devices, which AS 5369:2023 requires to be used immediately. Ozone and combined hydrogen peroxide and ozone systems have no process-specific standard, so efficacy is assessed to ISO 14937. Dry heat at 160 deg C [320 deg F] for 120 min or 180 deg C [356 deg F] for 60 min (ISO 20857) suits heat-stable items that do not tolerate moisture.

Process selection: AS 5369:2023 requires critical devices to be sterilised by moist heat after cleaning, with a low temperature process used only where the device is heat or moisture sensitive. Semi-critical devices that cannot withstand moist heat may be processed by low temperature sterilisation, thermal disinfection or high-level disinfection. Select the process from the device IFU.

Performance and Efficacy

Sterility assurance: Each validated terminal sterilisation process is designed to deliver a sterility assurance level (SAL) of one in a million, the probability of one viable microorganism remaining on a device after sterilisation. The SAL holds only where cleaning, packaging, load mass and load configuration match those qualified during PQ.

Steam: Lethality is set by temperature and time and is verified by physical measurement each cycle. Lethality is calculated as F0 using a z-value of 10 deg C [18 deg F], so a 3 deg C [5.4 deg F] shortfall halves the delivered lethality. Residual air and non-condensable gases prevent steam contact with device surfaces, so air removal, steam quality and chamber leak tightness are the controlling variables for porous and hollow loads.

Low temperature: Lethality depends on sterilant concentration, temperature, humidity and contact time at each surface. These cannot be measured at the device surface, so release relies on cycle records and on chemical and biological indicators. Oxidising sterilants (VH2O2, ozone, peracetic acid) react with organic soil and are consumed by it. Retained soil, residual moisture and cellulose reduce the dose at the device surface, so cleaning and drying efficacy set the process margin.

Lumens: VH2O2 penetration of lumens is limited by diffusion and by peroxide adsorption and decomposition on the lumen wall. Each cycle carries a lumen claim stated as a maximum length and minimum internal diameter, with separate claims for metal and polymer lumens. An indicative claim for a single-channel stainless steel lumen is 1 mm [0.04"] internal diameter by 500 mm [20"] length, a length to diameter ratio of 500 to 1. Measure each lumened device, confirm it falls within the claim for the selected cycle, and process devices outside the claim by another validated method.

EO: EO penetrates long lumens and packaging but requires humidity for lethality. Dried soil and salt crystals occlude microorganisms from the gas. AS 5369:2023 requires a biological indicator (BI) in every EO load and prohibits unloading before in-chamber aeration is complete.

Prions: AS 5369:2023 excludes reprocessing of devices potentially contaminated with transmissible spongiform encephalopathies and defers to the national Creutzfeldt-Jakob disease (CJD) infection prevention and control guideline. That guideline specifies single-use instruments where possible, quarantine of instruments used on higher-infectivity tissue until the patient's risk status is clarified, and exclusive use on that patient or incineration where the patient is at high or low risk. It recommends steam at 134 deg C [273 deg F] for 3 min for routine reprocessing, notes that aldehyde high-level disinfectants such as glutaraldehyde increase prion adherence to surfaces, and provides no low temperature process for prion inactivation. Do not treat an SAL as evidence of prion inactivation.

Material and Device Compatibility

Assessment: AS 5369:2023 requires the sterilising agent and process to be compatible with the device and the reprocessing equipment, assessed from the device IFU and documented. Where a process not listed in the IFU is proposed, assess the effect of repeated exposure and document the outcome. Every item in the chamber, including wraps, pouches, labels, indicators, trays and inserts, must be compatible with the sterilant.

Steam: Compatible with stainless steel, titanium, glass and polymers with a continuous service temperature greater than the process temperature and good hydrolysis resistance, e.g. PSU, PPSU, PEEK, PTFE and silicone. Not compatible with PVC, LDPE, polystyrene, most electronics, batteries and bonded optics unless the IFU states otherwise. Polypropylene and polycarbonate tolerate limited exposure at 121 deg C [250 deg F] only where the IFU permits. Retained moisture with chloride residue pits martensitic stainless steel, so control final rinse water quality and confirm packs are dry.

VH2O2: Compatible with most metals, many polymers and electronics because the process is dry and runs at less than 60 deg C [140 deg F]. Exclude cellulose (paper, cotton, linen, wood), liquids and powders. Copper and brass catalyse peroxide decomposition, which lowers the delivered concentration. Repeated oxidation can embrittle some elastomers and coatings, so track device condition against any IFU cycle limit.

EO: Compatible with almost all metals, polymers, elastomers, optics and electronics. Polymers with high EO solubility, e.g. PVC, need longer aeration to reach ISO 10993-7 limits. Paper, paper-plastic pouches and nonwoven wraps are permeable to EO.

LTSF: Limited to devices that tolerate 60 to 80 deg C [140 to 176 deg F] and steam. Incomplete desorption can leave paraformaldehyde deposits on devices.

Ozone: A strong oxidiser. Unsaturated elastomers such as natural rubber are subject to ozone cracking. Cellulose, textiles and liquids are excluded.

Packaging and indicators: Steam accepts medical paper, SMS nonwoven wrap, paper-plastic pouches and reusable rigid containers with filters. VH2O2 requires cellulose-free packaging, e.g. polypropylene nonwoven wrap and spunbonded polyolefin pouches, validated for the steriliser. Use chemical indicators to ISO 11140-1 and BIs to the applicable part of ISO 11138, selected for the process. Steam, VH2O2 and LTSF BIs commonly use Geobacillus stearothermophilus spores. EO and dry heat BIs use Bacillus atrophaeus spores. Label each pack with its intended process at packaging.

Operational Requirements and Workflow

Steam services: Large steam sterilisers require an electrical or plant steam supply, drainage rated for hot condensate, extraction for heat and moisture, and steam generator feedwater meeting AS 5369:2023 limits, including conductivity of 5 µS/cm or less at 20 deg C [68 deg F], hardness of 0.02 mmol/L or less and chloride of 0.5 mg/L or less. Test feedwater annually. Small sterilisers require feedwater to EN 13060. Liquid ring vacuum pumps consume water every cycle, while dry vacuum pumps or water recirculation reduce consumption. Test steam quality on large sterilisers at installation, relocation and any change to the steam supply: dryness value of 0.95 or more, non-condensable gases of 3.5 % v/v or less and superheat of 25 deg C [45 deg F] or less.

Pressure equipment: Large steam sterilisers are pressure equipment. Confirm the AS 4343 hazard level, whether item registration applies under Schedule 5 of the WHS Regulations, and the in-service inspection regime to AS/NZS 3788.

Steam routine monitoring:

• Daily air removal and steam penetration test (Bowie and Dick type) before first use on sterilisers that use vacuum air removal.
• Leak rate test on large sterilisers weekly where an automatic air detector is fitted, daily where it is not.
• Cycle record checked against the validated parameters after every cycle.
• External chemical indicator on each pack. BIs at a frequency set by the facility.
• Packs intact and dry at release. Cool loads in the dedicated cooling area before handling.

VH2O2 services: Typically an electrical supply only, with no plumbing or external exhaust where the IFU confirms. Store sterilant cassettes as an oxidiser per the safety data sheet (SDS) and within shelf life. Loads must be clean, fully dry, cellulose-free and within the IFU limits for load mass and lumen dimensions. Residual water evaporates under vacuum, prevents the chamber reaching the required pressure and cancels the cycle. Release requires a compliant cycle record, correct BI and external chemical indicator results as specified by the IFU, and intact, dry packs.

EO services: Install in a dedicated room with exhaust discharged to atmosphere, through an abatement system where the environmental authority requires it. Provide gas leak detection where the gas supply is not self-contained within the chamber. Store cartridges or cylinders as a flammable gas per the SDS. Place a BI in every load. Do not open the chamber until in-chamber aeration is complete. Conduct air monitoring to confirm exposure stays within the workplace exposure limit. Schedule cycles outside list hours and hold additional instrument sets to cover the 10 to 17 h turnaround.

LTSF and ozone services: LTSF requires water, drainage, formaldehyde handling per the SDS and air monitoring. Ozone systems require an oxygen supply and water for humidification, and catalytically convert residual ozone to oxygen before the chamber opens.

Workflow:

• Clean and dry every device before sterilisation. No process compensates for retained soil.
• Assign the process at inspection and packaging, from the IFU, then package and label for that process.
• Run steam and VH2O2 cycles between cases. Run EO and other long cycles outside list hours.
• Record each cycle. AS 5369:2023 requires critical devices to be traceable at least to the individual cycle of a specified steriliser.
• Assess operator competency for each process held, covering cycle selection, loading, record review and release. Train all personnel who handle chemical sterilants in safe handling, PPE, spills and exposure management.

Compliance and Standards in Australia

AS 5369:2023: Published 15 December 2023, superseding AS/NZS 4187:2014 and AS/NZS 4815:2006. It applies wherever reusable medical devices are reprocessed, including hospitals, day procedure centres, medical, dental and podiatry practices and aged care facilities.

NSQHS Standards: Hospitals and day procedure services are assessed against Action 3.17 of the Preventing and Controlling Infections Standard, which covers reprocessing of reusable equipment, instruments and devices. Australian Commission on Safety and Quality in Health Care (ACSQHC) Advisory AS24/01 required a gap analysis against AS 5369:2023 by 30 June 2025 and a risk-prioritised action plan to close the gaps.

Dental practices: The Dental Board of Australia retired its infection control guidelines on 1 July 2022. Practitioners must use guidance and processes that are evidence-based and relevant to the practice setting. AS 5369:2023 is the national standard for reprocessing.

External reprocessing: AS 5369:2023 requires a contract with any external reprocessing provider. Define responsibilities and conformance to AS 5369:2023 in the contract, and obtain evidence of the provider's accreditation and quality activities.

Cost Considerations

Basis: Compare processes on cost per cycle at the forecast utilisation, not on purchase price. Divide the whole-of-life cost by the cycles delivered over the service life. Include capital and installation (building services, ventilation, abatement), sterilant, utilities, indicators, planned maintenance and requalification, labour, device repair and replacement, and the instrument sets held to cover turnaround. Obtain quotations for purchase price and sterilant cost per cycle. The figures in this section are illustrative.

Utilisation: A low temperature steriliser at an illustrative A$120,000 over a 10 year life recovers A$7.69 of capital per cycle at 6 cycles per day for 260 days per year, and A$230.77 per cycle at 1 cycle per week. At low utilisation, capital recovery, not sterilant price, sets the cost per cycle.

Steam utilities: Generating 1 kg [2.2 lb] of saturated steam at 134 deg C [273 deg F] from feedwater at 15 deg C [59 deg F] requires about 2,660 kJ per kg [1,145 BTU per lb], or 0.74 kWh. A large steriliser using an assumed 15 kg [33 lb] of steam per cycle requires about 11.1 kWh [37,900 BTU], excluding standby losses. At A$0.30 per kWh this is A$3.33. Feedwater plus an assumed 150 L [40 US gal] of vacuum pump water, 165 L [43.6 US gal] in total at A$5 per kL [A$18.93 per 1,000 US gal], adds A$0.83, giving A$4.16 per cycle. Measure energy and water per cycle at commissioning and use the measured values.

Low temperature consumables: VH2O2 sterilant at an illustrative A$10 to A$12 per cycle plus an assumed 1.5 kWh of electricity (A$0.45) gives A$10.45 to A$12.45 per cycle before indicators. EO adds a gas cartridge (illustratively A$20 to A$30), a BI in every load with incubation, 8 to 12 h of heated aeration, exposure monitoring and abatement maintenance.

Device wear: Device cost per use equals purchase price divided by uses to replacement, plus repair cost per use. Where the IFU permits more than one process, record repairs and replacements by process. Example: a A$20,000 device replaced after 500 uses costs A$40 per use. If a different process extends its life to 1,000 uses, the A$20 per use saving exceeds the illustrative difference in sterilant and utility cost per cycle between steam and VH2O2 of A$6.29 to A$8.29.

Instrument inventory: Sets required equal the number of uses scheduled before the first set returns from reprocessing. Example: a device used 4 times on a list at 2 h intervals, with a 3 h return time (procedure, cleaning, packaging, VH2O2 cycle and release), needs 2 sets. With an EO process that returns the device the next day, it needs 4 sets. At an illustrative A$5,000 per set, the EO pathway adds A$10,000 of inventory.

Outsourcing and single use: Where utilisation is low, compare the in-house cost per cycle with the external provider's fee, transport and the additional sets needed to cover transit time. Where a device cannot be cleaned to its IFU, AS 5369:2023 prohibits reprocessing it and directs that a sterile single-use alternative be considered. Compare the single-use unit cost with the reprocessing cost per use.

Environmental and Safety Considerations

Regulatory basis: Chemical sterilants are hazardous chemicals under the WHS Regulations. Airborne exposure must not exceed the workplace exposure standard, which Safe Work Australia replaces with the Workplace exposure limits for airborne contaminants (WEL list) from 1 December 2026, subject to adoption in each jurisdiction. Conduct air monitoring where compliance with the limit is uncertain or monitoring is needed to determine the health risk, and provide health monitoring where the risk assessment identifies a significant risk. AS 5369:2023 requires an SDS for each sterilising agent, its precursors and by-products, procedures for storage, handling, decanting and disposal with PPE, a spill kit reviewed against each SDS, documented emergency procedures, training, and a documented assessment and control of environmental release.

Steam: Hazards are thermal and pressure related: burns from hot loads and surfaces, and steam release. Door interlocks prevent opening under pressure. Cool loads before handling and use heat-resistant gloves. Steam leaves no chemical residue on devices.

EO: Toxic, carcinogenic, mutagenic and extremely flammable. Controls are a dedicated room, exhaust, leak detection, no unloading before aeration is complete, air monitoring, flammable gas storage and a documented leak response. Where the environmental authority requires it, discharge through abatement, e.g. catalytic oxidation to carbon dioxide and water. Device residuals must meet ISO 10993-7.

VH2O2: Concentrated sterilant is an oxidiser and corrosive to skin and eyes. Handle cassettes per the SDS. Residual peroxide decomposes to water and oxygen. After a cancelled cycle, handle the load per the IFU and use the PPE specified in the SDS, as the load can retain peroxide.

LTSF and ozone: Formaldehyde is a carcinogen and sensitiser, so apply the same SDS, monitoring and ventilation controls as for EO. Ozone is a toxic oxidising gas. The steriliser converts it to oxygen before the chamber opens, and room ventilation is set by the risk assessment.

Environmental footprint: For steam, energy and water dominate. Run full validated loads, use dry vacuum pumps or water recirculation, and isolate steam generators outside operating hours where the IFU permits. Low temperature processes use less energy per cycle but generate sterilant cartridges and single-use packaging, and EO requires emissions control. Reusable rigid containers reduce wrap waste for steam where validated. Dispose of used cassettes and cartridges per the SDS and local waste requirements.

Implementation in Different Healthcare Settings

Hospital sterilising services: Use steam as the primary process for every device whose IFU permits it, with enough steam capacity to absorb breakdown and requalification downtime. Hold at least one low temperature process, selected from the IFUs of the heat-sensitive device inventory and sized to its cycle demand. Where a device IFU lists only a process the hospital does not hold, contract that process or select an alternative device. Install EO only where devices require it and the room, exhaust and monitoring controls are in place.

Day procedure centres: Use large or small steam sterilisers with cycles validated for wrapped and hollow loads. Justify a VH2O2 steriliser where heat-sensitive devices are used on most lists and its cycle time fits between cases. Otherwise outsource. Restrict device purchasing to devices whose IFU lists a process held on site or under contract.

Dental and office-based practices: Use small steam sterilisers to EN 13060. Process wrapped, porous and hollow loads, e.g. dental handpieces, in a Type B cycle. Type N cycles are limited to unwrapped solid instruments. Perform the daily air removal test on sterilisers that process packaged or hollow devices. Process heat-sensitive semi-critical devices, e.g. ultrasound probes, by low temperature sterilisation, thermal disinfection or high-level disinfection per the IFU. Hold low temperature sterilisation on site only where utilisation supports it. Otherwise outsource or use single-use devices.

Aged care facilities: Where reprocessing is limited to steam-tolerant instruments, e.g. podiatry and wound care sets, use a small steam steriliser operated to AS 5369:2023, an external provider under contract, or single-use instruments.

Selection procedure:

• List every reprocessed device with the processes its IFU permits.
• Assign steam to every device whose IFU permits it.
• Group the remaining devices by permitted low temperature process and estimate cycles per week.
• Select the low temperature process that covers the most devices, and confirm its material, load mass and lumen claims against each device.
• Calculate cost per cycle at the forecast utilisation and compare with outsourcing and single-use options.
• Size steam and low temperature capacity for peak demand plus breakdown and requalification downtime.

Conclusion and Recommendations

Steam is the default process for critical devices under AS 5369:2023. It has the lowest sterilant and utility cost per cycle, is verified by physical measurement each cycle and leaves no residue. Low temperature processes are required for heat and moisture sensitive devices and carry higher cost per cycle, stricter load limits and, for EO and LTSF, chemical exposure controls.

• Steam first: Sterilise every device whose IFU permits steam by steam.
• Select from the IFU: Choose the low temperature process from the IFUs of the devices it must process. Confirm ARTG inclusion, the equipment standard, and the material, load mass and lumen claims.
• Prefer VH2O2 where permitted: Its cycle runs in minutes rather than hours, needs no aeration and produces packaged devices that can be stored. Reserve EO for devices whose IFU requires it.
• Cost at utilisation: Calculate cost per cycle at the forecast utilisation. Outsource or use single-use devices where utilisation is low.
• Chemical safety: Maintain SDS, procedures, training and air monitoring for each chemical sterilant, and update exposure limits to the WEL list from 1 December 2026.
• Monitoring and release: Apply the routine monitoring and release criteria of AS 5369:2023 for each process, with annual requalification.
• Prions: Manage devices used on higher-infectivity tissue under the national CJD infection prevention and control guideline.

Sources

1. Standards Australia. AS 5369:2023 Reprocessing of reusable medical devices and other devices in health and non-health related facilities.
2. Australian Commission on Safety and Quality in Health Care. National Safety and Quality Health Service Standards.
3. Australian Commission on Safety and Quality in Health Care. Advisory AS24/01 Requirements for reprocessing of reusable medical devices in health service organisations.
4. Communicable Diseases Network Australia. Creutzfeldt-Jakob disease infection prevention and control recommendations for health care settings, 2013.
5. Safe Work Australia. Model Work Health and Safety Regulations, Part 7.1 Hazardous chemicals and Schedule 5 Registration of plant and plant designs.
6. Safe Work Australia. Workplace exposure limits for airborne contaminants, applying from 1 December 2026.
7. Dental Board of Australia. Infection prevention and control, frequently asked questions.
8. ISO 22441 Sterilization of health care products, Low temperature vaporized hydrogen peroxide.
9. ISO 11135 Sterilization of health-care products, Ethylene oxide.
10. ISO 10993-7 Biological evaluation of medical devices, Part 7: Ethylene oxide sterilization residuals.
11. ISO 25424 Sterilization of health care products, Low temperature steam and formaldehyde.
12. ISO 14937 Sterilization of health care products, General requirements for characterization of a sterilizing agent.
13. EN 13060 Small steam sterilizers.
14. AS 4343 Pressure equipment, Hazard levels. AS/NZS 3788 Pressure equipment, In-service inspection.