Frequently Asked Questions

Recognised Standard 20 (RS20) is Queensland's Dust Control in Surface Mines recognised standard. It provides guidance and requirements for managing respirable dust hazards at surface mines and includes requirements relevant to operator enclosures and cabin air-quality systems. RS20 is listed by the Queensland Government among Queensland's recognised mining standardsn text goes here

WEL stands for Workplace Exposure Limit. In Australia, Workplace Exposure Limits specify the maximum airborne concentration of certain hazardous substances that workers may be exposed to in the workplace.

From 1 December 2026, WELs will replace the existing Workplace Exposure Standards (WES), subject to implementation under the applicable WHS legislation.

WELs are used to help workplaces assess and control worker exposure to airborne contaminants such as respirable dust, respirable crystalline silica, diesel particulate matter and hazardous gases.

A WEL is an exposure limit, not a specification for a particular control measure or filtration system. Workplaces must continue to eliminate or minimise risks from airborne contaminants so far as is reasonably practicable.

For mobile plant operating in environments containing dust, silica, diesel emissions or other airborne contaminants, the applicable requirements should be determined through a workplace risk assessment and consideration of the relevant WHS legislation, exposure limits, codes of practice and applicable standards.

ISO 23875 specifies a minimum sustained cabin pressurisation of 20 Pa and a maximum sustained pressurisation of 200 Pa under the specified conditions. The standard's minimum pressure requirement is associated with the machine starting device being in the "on" position. RS20 and ISO 23875 should not simply be treated as having identical pressure requirements. Industry guidance comparing the requirements identifies RS20 as requiring at least 50 Pa without a pressure monitor or a lower 20 Pa threshold applicable where the cabin is fitted with pressure monitoring and an alarm for pressure below 20 Pa.

No. Positive cabin pressure alone does not establish compliance with ISO 23875 or Queensland RS20.

Maintaining positive pressure is an important part of controlling the entry of contaminated air into an operator enclosure. However, compliance involves the overall performance of the operator enclosure and air-quality control system, including applicable requirements for pressure, filtration, cabin air quality, monitoring, testing and maintenance.

ISO 23875 provides performance requirements and test methods for air-quality control systems used in operator enclosures.

Queensland RS20 – Recognised Standard 20: Management of Respirable Dust in Queensland Mineral Mines also includes requirements relevant to operator enclosures and dust control.

Therefore, a cabin should not be considered compliant solely because it maintains a positive pressure. The complete system and enclosure should be assessed against the applicable requirements of the relevant standard and workplace conditions.

In addition, compliance with ISO 23875 or RS20 does not automatically demonstrate compliance with applicable WHS legislation or Workplace Exposure Limits (WEL). These requirements should be considered separately as part of the overall risk-control process.

Maintaining positive pressure inside an operator cabin helps reduce the ingress of contaminated outside air and respirable dust through gaps, seals and other leakage points.

Cabin pressurisation should be considered as part of a complete air-quality control system, together with appropriate filtration, cabin sealing, monitoring and maintenance

Cabin seals are critical to maintaining pressurisation.

Doors, windows, access panels, electrical penetrations, hydraulic penetrations, structural joints and other potential leakage points should be maintained so that the enclosure can maintain the required pressure.

Damaged or deteriorated seals can significantly increase leakage and reduce system performance

ISO 23875 includes requirements relating to carbon dioxide concentration inside the operator enclosure.

The maximum sustained CO₂ level specified by the standard is the ambient CO₂ concentration plus 400 ppm, subject to the measurement and test conditions specified by the standard.

CO₂ can build up inside an enclosed operator cabin due to operator respiration and insufficient ventilation or outside-air supply.

Monitoring CO₂ provides an additional indication of whether adequate fresh-air exchange is being maintained.

Testing frequency should be determined according to the applicable standard, equipment requirements, manufacturer's recommendations, site procedures and risk assessment.

Routine inspection and testing should also be considered following maintenance, filter replacement, modifications, repairs to cabin seals or other work that could affect enclosure integrity or system performance.

In many cases, an existing operator enclosure can be fitted or upgraded with an air-quality control system.

However, the enclosure, sealing, filtration, airflow, pressure monitoring and other components need to be assessed as a complete system.

A retrofit should be designed and tested against the applicable requirements rather than assuming that installing a pressuriser alone makes the cabin compliant.

Depending on the system and applicable requirements, an inspection may include:

Cabin doors and door seals

Windows and window seals

Access panels

HVAC and ventilation components

Cabin air filters

Filter housings and seals

Fan/blower operation

Airflow

Cabin pressure

Pressure monitoring and alarms

CO₂ monitoring

Respirable particulate levels

Electrical and hydraulic penetrations

Structural and other potential leakage points

Operator controls and warning indicators

What should the operator do if the cabin pressure alarm activates?

The operator should follow the machine manufacturers and site-specific procedures.

Generally, a pressure alarm should be treated as an indication that the cabin air-quality control system may not be operating as intended. The cause should be investigated rather than simply resetting or ignoring the alarm.

Where required by the site's risk controls, the operator may need to leave the contaminated area or use the specified respiratory protective equipment until the cabin protection system has been restored

Not necessarily.

Compliance with AS/NZS ISO 23875 addresses the requirements covered by that standard. Other Australian legislation, regulations, codes of practice, machinery standards, mine-site requirements and risk controls may also apply.

A complete compliance assessment should consider all requirements applicable to the particular machine and operating environment.

What documentation should be retained?

A documented cabin air-quality control program should typically include relevant information such as:

Equipment identification

Cabin identification

Test results

Cabin pressure measurements

Particulate test results

CO₂ measurements

Filter specifications and replacement records

Maintenance records

Inspection records

Calibration records for monitoring equipment

Alarm verification

Repairs and modifications

Non-conformance and corrective-action records

Operator instructions and training records

The exact documentation requirements should be established for the equipment, workplace and applicable compliance framework.

Replacing the cabin filters with a Hepa filter will cause poor air flow in the cabin HVAC system. The cabin will Also not be able to maintain a positive pressure because there is not powered fresh air motor. The system will rely on the fan speed setting of the HVACV system. There is also a requirement for system monitoring for the ISO 23875 regulations.

Cabin pressurisation controls the direction of air movement by maintaining higher pressure inside the cabin than outside.

Filtration removes contaminants from the air supplied to the cabin.

Both are important components of an effective operator-enclosure air-quality control system.

A cabin that cannot maintain the required pressure should be investigated.

Possible causes include blocked or incorrectly installed filters, inadequate fan performance, excessive cabin leakage, damaged door or window seals, open access points, incorrect HVAC settings or faults within the pressurisation system.

A structured inspection and pressure/leakage assessment can help identify the cause.

Simply sealing the operator cabin is not a practical solution for controlling airborne contaminants.

A sealed cabin still requires a controlled supply of clean, filtered air to maintain suitable air quality & fresh air to keep CO2 levels down. Without a pressurised cabin dust will accumulate in the cabin over time.

CleanCab supplies cabin filtration and pressurisation systems for mobile plant and equipment, designed to help control airborne contaminants within operator cabins.

Our systems can be configured to provide:

• Cabin pressurisation systems to help prevent contaminated outside air entering the operator enclosure.

• Pre-filtration to capture larger airborne particles and protect downstream filtration.

• H14 HEPA filtration for high-efficiency removal of fine airborne particulate contaminants, including respirable dust, respirable crystalline silica and diesel particulate matter.

• Gas-phase filtration using specialised media for the removal of selected gaseous contaminants.

• Activated carbon and chemically impregnated media filtration, where appropriate for the contaminants present.

• Combined particulate and gas-phase filtration configurations to address both particulate and gaseous contaminants.

• Powered Recirculation filtration systems for additional treatment of cabin air.

• Cabin pressure monitoring and control to assist in maintaining the required positive cabin pressure.

Systems can be configured for different mobile plant applications and airflow requirements.

CleanCab systems are intended to form part of an overall workplace exposure-control strategy and can be configured with reference to applicable requirements and standards, including WHS requirements, Workplace Exposure Limits (WEL), ISO 23875 and Queensland RS20, where applicable.

The appropriate filtration and pressurisation configuration depends on the contaminants present, operating environment, cabin characteristics and required airflow. Product selection should therefore be based on the specific application and exposure risks.

"Our cabin filtration and pressurisation systems are designed to assist in controlling exposure to airborne contaminants, including respirable dust, respirable crystalline silica and diesel particulate matter, in accordance with applicable Australian WHS requirements and relevant cabin air-quality standards."

Cleancab Filtration systems & dealers can provide documentation recording the measured results, equipment tested, test conditions, identified deficiencies and recommended corrective actions

Cleancab Filtration systems can carry out cabin air-quality assessment that can include pressure testing, system inspection, monitoring verification and assessment of the air-quality control system against the applicable requirements of AS/NZS ISO 23875 & RS20.

Contact us to discuss your machine, cabin and operating environment.