Compressed air is a critical utility in pharmaceutical manufacturing, yet it remains one of the most common sources of TGA audit findings. Unlike medicinal gases, which require separate TGA registration, utility compressed air falls under Good Manufacturing Practice (GMP) requirements and must be qualified, monitored, and documented to the same rigour as purified water or clean steam.
This guide maps Australia’s current GMP framework to specific compressed air system requirements, including ISO 8573-1 quality classes for different product contact levels, system specification principles, and the monitoring and validation protocols that TGA auditors expect to see during inspections.
By Byron Raal, CAS Founder-Editor · Last updated 10 May 2026 · About the author
Why TGA GMP Compliance Matters for Compressed Air
The Therapeutic Goods Administration (TGA) is Australia’s regulatory authority for medicines, medical devices, and biologicals. Every pharmaceutical manufacturer operating in Australia must hold a TGA manufacturing licence and comply with the GMP requirements set out in the PIC/S Guide to GMP.
Compressed air touches pharmaceutical products in ways that are easy to overlook: tablet coating, fluid bed drying, vessel pressurisation, conveyor transport, packaging line blow-off, and instrument air for control valves. If contaminated air reaches the product, the consequences range from batch rejection and costly rework through to product recall, patient harm, and suspension of the manufacturing licence.
TGA auditors assess compressed air as part of the facility’s utility qualification programme. A finding against compressed air can escalate from an observation to a critical non-conformance if the manufacturer cannot demonstrate that air quality is controlled, monitored, and documented. In serious cases, the TGA can issue a direction to cease manufacturing until the deficiency is resolved.
TGA’s Adoption of PIC/S Guide to GMP (PE009-17)
Australia’s GMP requirements are based on the PIC/S Guide to Good Manufacturing Practice for Medicinal Products (PE009-17), which was published by PIC/S on 25 August 2023 and adopted by the TGA effective 1 September 2025. This version incorporates the revised Annex 1 for sterile medicinal products, a significant update that strengthens requirements for utilities including compressed air.
The PIC/S Guide is divided into two parts and twenty annexes. For compressed air compliance, three sections are particularly relevant.
Part I, Chapter 3 (Premises and Equipment) requires that utilities which could affect product quality, including compressed air, are qualified and monitored. The system must be designed to minimise contamination risk, with appropriate filtration and drying at points of use.
Annex 1 (Manufacture of Sterile Medicinal Products) now requires a formal Contamination Control Strategy (CCS) covering all utilities that contact the product or aseptic environment. Compressed air and process gases must be included in this strategy, with risk assessments determining air quality specifications at each point of use.
Annex 15 (Qualification and Validation) sets out the framework for qualifying compressed air systems through installation qualification (IQ), operational qualification (OQ), and performance qualification (PQ). Ongoing verification through periodic requalification and routine monitoring is mandatory.
Contamination Control Strategy: What Annex 1 Requires from 1 September 2025
The revised PIC/S Annex 1, incorporated into PE009-17 and effective in Australia from 1 September 2025, introduces a formal Contamination Control Strategy (CCS) requirement covering every utility in contact with sterile products or aseptic environments. For compressed air, this means documenting how the system prevents particulate, microbial, chemical, and cross-contamination risks across its entire lifecycle, from compressor intake to point-of-use delivery.
A compliant CCS for compressed air typically covers: the intake air quality assessment (proximity to traffic, exhausts, or other contamination sources); the rationale for compressor technology selection (oil-free vs oil-injected with documented justification); the filtration train specification with redundancy considerations; the dryer selection and pressure dew point justification; the distribution pipework materials and dead leg control strategy; the point-of-use filter integrity testing programme; the microbiological monitoring frequency with trigger thresholds; and the response procedure for out-of-specification results including batch impact assessment. TGA inspectors trained to the 2022 Annex 1 revision now expect to see this document as a standalone deliverable rather than as scattered references across the Site Master File.
Facilities that manufactured under the older Annex 1 (PE009-14 and earlier) should treat CCS preparation as a priority gap-closure exercise. A CCS that bolts together existing documents without genuine cross-functional review is a common 2025 to 2026 audit finding pattern. The most defensible CCS documents are built by a cross-functional team (engineering, QA, microbiology) over three to six months, with sign-off at the site quality council and annual review triggered by any change to compressor, dryer, filtration, or distribution that could affect sterile product quality.
Medicinal Air vs Utility Compressed Air
A critical distinction that pharmaceutical manufacturers must understand is the difference between medicinal air and utility compressed air, because they follow entirely separate regulatory pathways.
Medicinal air is classified as a therapeutic good under the Therapeutic Goods Act 1989. It must be listed on the Australian Register of Therapeutic Goods (ARTG) and manufactured under a separate TGA licence specifically for medicinal gases. The TGA’s medicinal gases guidance sets out specific requirements for production, testing, and release of medicinal air intended for patient administration.
Utility compressed air is a process utility used in manufacturing operations. It does not require ARTG listing, but it must comply with GMP requirements for critical utilities under the PIC/S Guide. The manufacturer is responsible for defining air quality specifications based on a risk assessment of each application, qualifying the system, and maintaining an ongoing monitoring programme.
This guide focuses on utility compressed air, which is the responsibility of the pharmaceutical manufacturer’s engineering and quality teams rather than a registered gas supplier. Most TGA audit findings related to compressed air concern utility systems, not medicinal gas installations.
ISO 8573-1 Air Quality Classes for Pharmaceutical Applications
The PIC/S Guide does not prescribe specific compressed air quality classes. Instead, it requires manufacturers to define specifications based on a documented risk assessment. In practice, the pharmaceutical industry uses ISO 8573-1:2010 as the reference standard for specifying and testing compressed air quality.
ISO 8573-1 defines air quality using three separate class numbers for particles, water, and oil (written as X.Y.Z). The class required depends on the level of contact between compressed air and the pharmaceutical product.
| Contact Level | Typical Application | ISO 8573-1 Class | Key Requirements |
|---|---|---|---|
| Direct product contact | Tablet coating, fluid bed drying, vessel purging, product conveying | 1.2.1 | Oil-free compressor typical. Desiccant dryer to -40 °C PDP minimum. Sterile grade final filtration at point of use. |
| Indirect contact (product contact surfaces) | Equipment cleaning blow-down, autoclave air supply, isolator air | 2.4.2 (CAS engineering view; site-validated under quality risk assessment, not TGA-prescribed) | Oil-free preferred. Refrigerated dryer acceptable for moisture (+3 °C PDP) where Class 4 water is sufficient under site validation. Particulate filtration to 0.01 µm. |
| Non-contact utility | Instrument air, pneumatic actuators, general plant services | 3.4.3 (CAS engineering view; site-validated under quality risk assessment, not TGA-prescribed) | Oil-injected compressor with coalescing filtration acceptable. Refrigerated dryer sufficient. |
| Sterile applications | Aseptic filling line, sterile powder handling | 1.1.1 or 0.1.1 | Oil-free compressor. Deep desiccant drying to -70 °C PDP. 0.2 µm sterile membrane filter with integrity testing. |
The three numbers represent: particles (Class 1 permits a maximum of 20,000 particles at 0.1 to 0.5 µm per cubic metre), water (Class 2 requires a pressure dew point of -40 °C or lower), and oil (Class 1 limits total oil to 0.01 mg/m³ or less). Each class is defined independently, and manufacturers must specify all three based on their risk assessment.
A common error is specifying a single combined “Class 2” for pharmaceutical air. ISO 8573-1 always requires three separate class numbers. Another frequent mistake is assuming a refrigerated dryer can achieve the water classes needed for direct product contact. A refrigerated dryer achieves a pressure dew point of approximately +3 °C, which corresponds to Class 4 water at best. Direct product contact applications requiring Class 2 water (-40 °C PDP) need a desiccant dryer.
Specifying a TGA-Compliant Compressed Air System
A pharmaceutical compressed air system that satisfies TGA GMP requirements typically includes the following components, selected and sized based on the facility’s risk assessment and air quality specifications.
Oil-free compressor. For applications where compressed air contacts the product or product-contact surfaces, achieving ISO 8573-1:2010 Class 1 oil (≤0.01 mg/m³ total oil including aerosol and vapour) is typically the design target. ISO 8573-1 is a classification framework, not an equipment specification: Class 1 can be reached either with an oil-free (Class 0 lubricant) compressor, or with an oil-lubricated compressor followed by a coalescer-polisher stack plus activated-carbon adsorber, provided the achieved oil content is verified by ISO 8573-2 (aerosol) and ISO 8573-5:2025 (vapour) testing.
ISO 8573-1 Class 0 is a separate user-defined specification. Class 0 has no fixed numeric value; the standard requires the user to specify a stricter threshold than Class 1 and to document both the equipment selected to achieve it and the validation programme that confirms it. Selecting Class 0 is therefore a documentation and validation exercise, not the result of installing a particular filter stack: a coalescer-polisher train alone does not entitle a system to a Class 0 claim. For sterile injectables, ophthalmics or inhalation products where Class 0 is appropriate, the typical configuration is a Class 0-lubricant oil-free compressor backed by redundant 0.01 µm coalescing filtration, an activated-carbon adsorber, point-of-use sterile filtration, and a validation programme that includes routine ISO 8573-2 and ISO 8573-5:2025 measurement against the user-defined threshold.
Oil-injected compressors with downstream coalescing filters are acceptable for non-contact utility air but introduce a residual oil risk that must be managed through monitoring.
Desiccant dryer. Direct product contact applications require a desiccant dryer capable of achieving -40 °C pressure dew point (ISO 8573-1 Class 2 water) or lower. Heatless desiccant dryers are most common in pharmaceutical installations. Sterile applications may require deep desiccant drying to -70 °C PDP (Class 1 water). A refrigerated dryer (+3 °C PDP, Class 4 water) is only suitable for non-contact utility air.
Sterile filtration. Point-of-use sterile filters (0.2 µm membrane) are required for aseptic applications and recommended for direct product contact. These filters must be integrity tested (bubble point or diffusion test) at defined intervals, with results recorded. Upstream coalescing filters (0.01 µm) remove oil aerosol and fine particulate before the sterile filter.
Distribution pipework. Pharmaceutical compressed air distribution should use electropolished stainless steel (316L) or high-purity aluminium piping with orbital-welded or compression fittings. Dead legs must be minimised. The system should be designed for Clean-In-Place (CIP) or Steam-In-Place (SIP) capability where required by the Contamination Control Strategy.
Monitoring points. The system must include permanent monitoring or sampling points at critical locations: compressor outlet, after each treatment stage (dryer, filters), and at representative points of use. Online monitoring for dew point and particle count is increasingly expected by TGA auditors, particularly for direct product contact applications.
For a facility running a 75 kW oil-free compressor at 8 bar for 16 hours per day, energy costs alone reach approximately $131,400 per year at Australian industrial electricity rates (approximately $0.30 per kilowatt-hour as of 2026; actual rates vary by state, tariff, and contract). With energy typically representing 70 to 80 percent of a compressor’s total cost of ownership over ten years, right-sizing the system and minimising leaks through a structured leak detection programme are essential for controlling operating costs.
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Monitoring, Validation, and Documentation
TGA auditors expect pharmaceutical compressed air systems to be fully qualified under the PIC/S Annex 15 framework and maintained through an ongoing monitoring programme with complete documentation.
System Qualification (IQ/OQ/PQ)
Installation Qualification (IQ) verifies that the compressed air system has been installed according to the approved design specification. This includes confirming equipment models, materials of construction, piping layout, weld certifications (for stainless steel), filter specifications, and instrumentation calibration certificates.
Operational Qualification (OQ) demonstrates that the system operates within specified parameters across its operating range. Key parameters include discharge pressure, flow capacity, dew point at each treatment stage, particle counts, and oil vapour concentration. OQ testing should cover normal operating conditions, maximum demand, and relevant upset scenarios.
Performance Qualification (PQ) confirms that the system consistently delivers air meeting the specified ISO 8573-1 classes under actual production conditions over an extended period, typically three consecutive production campaigns or a defined calendar period (commonly 6 to 12 months of data).
Ongoing Monitoring
After qualification, the compressed air system requires routine monitoring. While the PIC/S Guide does not mandate specific frequencies, the following programme reflects current TGA auditor expectations and industry practice in Australia.
| Parameter | Test Method | Typical Frequency | Acceptance Criteria |
|---|---|---|---|
| Dew point | Online hygrometer or manual spot check | Continuous (online) or weekly (manual) | Per ISO 8573-1 water class at each point |
| Particle count | Laser particle counter per ISO 8573-4 | Quarterly at points of use | Per ISO 8573-1 particle class |
| Oil content (aerosol + vapour) | Detector tubes or photoacoustic per ISO 8573-2 and ISO 8573-5:2025 | Quarterly at points of use | Per ISO 8573-1 oil class |
| Microbiological | Impaction or filtration sampling | Risk-based per the site’s Contamination Control Strategy. PIC/S Annex 1 Clause 6.19 requires periodic point-of-use microbial monitoring without prescribing a universal cadence; common industry practice ranges monthly (highest risk) to annually (lowest risk) depending on contact zone and historical data. PIC/S Cl 6.18 frames the parameter specification as risk-based. | Facility-defined limits based on risk assessment |
| Filter integrity | Bubble point or diffusion test | After each filter change and six-monthly | Per filter manufacturer specification |
All monitoring results must be recorded, trended, and reviewed. Out-of-specification results trigger a deviation investigation under the facility’s quality management system. The investigation must assess potential impact on any batches manufactured since the last passing result.
Documentation Requirements
TGA auditors review compressed air documentation as part of the utility qualification file. Essential documents include the User Requirements Specification (URS), risk assessment for air contact classification, qualification protocols and reports (IQ/OQ/PQ), routine monitoring SOPs and results, preventive maintenance schedules and records, filter change-out and integrity test logs, deviation reports and CAPA records, change control records for any system modification, and annual Product Quality Reviews (PQRs) that include compressed air trend data.
Change control is particularly important. Any modification to the compressed air system, whether replacing a compressor, changing filter grades, altering piping, or adjusting monitoring frequency, must go through the facility’s change control process with a documented impact assessment and, where necessary, requalification.
Common TGA Audit Failures Related to Compressed Air
Based on published TGA GMP clearance inspection outcomes and industry experience, the following compressed air findings recur across pharmaceutical manufacturing sites in Australia.
No documented risk assessment for air contact classification. The manufacturer uses compressed air in multiple applications but has not formally assessed which applications involve direct product contact, indirect contact, or non-contact. Without this risk assessment, air quality specifications cannot be justified and the monitoring programme has no basis.
Incomplete or missing qualification documentation. The compressed air system was commissioned but never formally qualified under IQ/OQ/PQ. Alternatively, the original qualification exists but the system has been modified (compressor replacement, piping extension) without requalification through change control.
Inadequate monitoring programme. Monitoring is limited to dew point only, with no particle or oil testing. Alternatively, testing is performed annually rather than quarterly, or monitoring points do not cover all critical points of use. Some facilities test at the compressor room outlet but not at points of use, missing contamination introduced by the distribution system.
Wrong dryer type for the application. A refrigerated dryer is installed on a system supplying direct product contact air, but the risk assessment specifies Class 2 water (-40 °C PDP). The refrigerated dryer achieves +3 °C PDP at best (Class 4 water), leaving a gap between the specification and the actual system capability.
Filter management failures. Sterile filters are not integrity tested after installation. Filter change-out intervals are based on calendar time alone without considering differential pressure monitoring. No traceability between filter serial numbers and the specific point-of-use location.
No trending of monitoring data. Results are recorded but not trended or reviewed. Gradual deterioration in air quality (increasing particle counts, rising dew point) goes undetected until a point-of-use test fails, potentially affecting multiple batches manufactured since the last passing result.
Testing not performed by NATA-accredited laboratory. While not an absolute regulatory requirement, TGA auditors increasingly expect that ISO 8573 compressed air testing is performed by a laboratory with NATA accreditation for the relevant test methods. Using an unaccredited provider can be raised as an observation and undermines confidence in the monitoring data.
Australian-Specific Requirements
Beyond the PIC/S GMP framework, pharmaceutical compressed air systems in Australia must comply with several additional requirements.
Pressure vessel registration. Air receivers and any pressure vessels operating above the thresholds specified in AS 1210-2010 (Pressure Vessels) must be registered with the relevant state or territory work health and safety regulator. Registration requirements and inspection intervals vary between jurisdictions. Failure to register pressure vessels is a separate regulatory breach that can compound a GMP finding.
NATA-accredited testing. The National Association of Testing Authorities (NATA) accredits laboratories and testing organisations against ISO/IEC 17025. For pharmaceutical compressed air, NATA accreditation is available for ISO 8573-4 (particle testing), ISO 8573-3 (moisture measurement), and ISO 8573-2 and ISO 8573-5:2025 (oil aerosol and vapour). Using a NATA-accredited provider strengthens the defensibility of monitoring data during TGA audits.
TGA auditor expectations. TGA GMP inspectors are members of the PIC/S and trained to the same standards as European inspectors. They expect to see a lifecycle approach to compressed air: design qualification through to ongoing monitoring, with complete traceability. Australian pharmaceutical manufacturers are also subject to unannounced inspections, making continuous compliance essential rather than audit preparation alone.
State and territory variations. While TGA GMP requirements are national, pressure equipment registration, workplace health and safety obligations, and environmental permits for compressor noise and condensate discharge are administered by state and territory authorities. Manufacturers must satisfy both the national GMP requirements and local regulatory obligations.
Frequently Asked Questions
What ISO 8573-1 class do I need for direct-contact pharmaceutical air?
For compressed air with direct product contact in a sterile or non-sterile pharmaceutical process, the default Australian practice is ISO 8573-1 Class 1 for particles, Class 2 for water, and Class 1 for oil, written 1.2.1. Where the product must remain oil-free (injectables, ophthalmic, inhalation), move oil to Class 0 with a written oil-free specification. For indirect contact (vial rinsing upstream of sterilisation), Class 2.4.2 is usually defensible. Non-contact (instrument air) is typically 3.4.3. The class choice must be tied to a risk assessment, not to vendor default.
What changed when Australia adopted PIC/S PE009-17?
PIC/S Guide to GMP PE009-17 took effect for Australian pharmaceutical manufacturers on 1 September 2025. It pulled through the revised Annex 1 on sterile product manufacture, which reframes compressed air as a critical utility and requires a documented Contamination Control Strategy (CCS) that explicitly covers it. In practice, that means compressed air for sterile product contact now needs risk-based classification, routine monitoring, deviation management, and a maintained audit trail, not just a one-off commissioning test. Sites still running pre-2025 commissioning data should assume a TGA finding is coming.
Does Annex 1 actually require a contamination control strategy for compressed air?
Yes, Annex 1 section 2 is explicit: the CCS must cover every utility that contacts product or product-contact surfaces, and compressed air almost always does one or both. The CCS needs to identify the points of use, the contamination risks at each (particles, water, oil, viable organisms), the controls applied (filtration stages, dryer type, sampling frequency), and how those controls are verified. Auditors now open Annex 1 audits by asking to see the CCS, not by asking for the annual test certificate. If your CCS does not name compressed air as a covered utility, fix that first.
How often does pharmaceutical compressed air need to be retested?
A defensible Australian baseline is annual full ISO 8573-1 requalification for particles, water, and oil, plus quarterly microbial sampling at every product-contact use point, tightened to monthly during any routine production. Change-driven re-testing is also required: after filter changes, dryer service, distribution changes, or any deviation that could affect air quality. Do not rely on the commissioning certificate past 12 months, and do not rely on a single sample point to cover a whole distribution network. Each point of use is its own qualification.
What are the most common TGA audit findings on compressed air?
The recurring findings, in rough order of frequency: (1) CCS does not list compressed air as a covered utility, (2) sampling frequency not justified by risk assessment, (3) test scope missing microbial or oil where contact risk is present, (4) commissioning certificate being used years after install with no re-qualification, (5) filter change records not linked to requalification, and (6) sample port locations that do not represent the worst-case use point. Most are documentation gaps rather than engineering failures, which means they are fixable inside 60 days if the plant is otherwise in order.
Who performs the testing, in-house or NATA-accredited?
Microbial and total particle counts can be run in-house with validated equipment and trained personnel, provided the method is documented and the results are treated as GMP records. Oil content (Class 0 or Class 1 claims) and formal ISO 8573-1 requalification should be run by a NATA-accredited laboratory against ISO/IEC 17025, because the TGA will accept NATA paperwork without further argument. The in-house-versus-NATA split is a commercial call: monthly microbial in-house plus annual NATA requalification is the usual middle ground for a mid-size Australian site.
Related Resources
- Pharmaceutical Industry Compressed Air Guide
- Compressed Air Filtration: Australian Specification Guide
- Oil-Free Compressors: Australian Specification Guide
- Compressed Air Dryers and Air Quality
- Compressed Air System Design Guide
External References
- TGA: GMP Requirements for Medicinal Products (PIC/S PE009-17)
- PIC/S: Guide to Good Manufacturing Practice Publications
- Standards Australia: AS ISO 8573-1:2010 Compressed Air Quality Classes
- NATA: National Association of Testing Authorities Australia
- Safe Work Australia: Pressure Equipment Requirements
- Dew point calculator: Specify Class 2 water for TGA pharmaceutical applications using the Magnus-Tetens conversion tool
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