When Does a Workplace Need Air Monitoring?

Dust, fumes, vapours and gases are part of everyday work in many industries. They can be generated by cutting concrete, welding metal, operating diesel equipment, spraying chemicals, handling powders or simply carrying out a routine production process.

The difficulty is that you cannot always see, smell or otherwise detect an airborne contaminant. And even when you know it is present, it may not be obvious whether workers are being exposed at a harmful level. This is where workplace air monitoring becomes important.

In Australia, air monitoring can be required where there is uncertainty about the level of an airborne contaminant or where monitoring is needed to determine whether exposure presents a risk to health.

But when exactly should a workplace arrange it, what does air monitoring involve, and what should happen after the results come back?

What is workplace air monitoring?

Workplace air monitoring involves measuring the concentration of contaminants in the air that workers may breathe.

Airborne contaminants can include:

• dusts

• fumes

• gases

• vapours

• mists

• fibres.

Some originate from hazardous chemicals being used at work. Others are generated by the work itself.

For example, respirable crystalline silica can be released when cutting or grinding materials containing silica. Welding can produce metal fumes, diesel engines generate emissions, and solvents can release vapours into the surrounding air.

Air monitoring used to assess worker exposure will commonly involve a worker wearing a personal sampling device positioned in their breathing zone while carrying out their normal duties. This provides information about the concentration of the contaminant to which the worker may actually be exposed.

When is air monitoring required?

Under the model Work Health and Safety Regulations, a person conducting a business or undertaking (PCBU) must carry out air monitoring to determine the airborne concentration of a substance or mixture where:

1. there is uncertainty, on reasonable grounds, about whether the airborne concentration exceeds the applicable workplace exposure standard or limit; or

2. monitoring is necessary to determine whether there is a risk to health.

This means air monitoring should not simply be thought of as something reserved for obviously dusty or heavily contaminated workplaces. The real question is whether the organisation has enough reliable information to understand workers' exposure. If the answer is uncertain, monitoring may be required.

1. When you do not know whether an exposure limit is being exceeded

One of the clearest triggers for air monitoring is uncertainty. A workplace may know that a contaminant is present but have little evidence about its actual airborne concentration.

For example, workers may regularly cut, grind or drill materials that generate dust. Controls such as extraction, water suppression and respirators may be in place, but the organisation may not have evidence demonstrating the level of exposure created during the task. In this situation, simply assuming the controls are sufficient may not be enough.

Air monitoring can provide objective exposure data and help determine whether workers are being exposed above the applicable limit.

2. When the level of exposure may present a health risk

Air monitoring can also be required even where the organisation is not simply trying to establish compliance with a numerical exposure limit.

Safe Work Australia notes that there are more than 600 substances and mixtures with an established workplace exposure standard or workplace exposure limit, but there are also hazardous substances for which no mandatory exposure limit exists. WHS duties to eliminate or minimise exposure risks still apply regardless of whether a specific numerical limit has been established.

That distinction matters.

An exposure limit should not be treated as a dividing line between "safe" and "unsafe". Exposure should still be eliminated or minimised so far as is reasonably practicable.

Air monitoring can therefore form part of a broader assessment of whether an airborne contaminant is creating a health risk.

3. When work processes generate hazardous airborne contaminants

It is easy to focus only on chemicals that arrive at the workplace in containers. However, some of the most important airborne contaminants are generated by the work process itself.

Examples may include:

• respirable crystalline silica from cutting stone, concrete or other silica-containing materials

• welding fumes

• wood dust

• diesel engine emissions

• metal dust or fumes

• spray mists

• combustion products

• dust generated during crushing, drilling, sanding or grinding.

Safe Work Australia specifically recognises that work processes can release dusts, gases, fumes, vapours and mists that may pose a risk to health. Organisations therefore need to consider not only which hazardous chemicals they purchase and store, but also what contaminants are created during normal operations.

4. When workplace conditions or processes change

Existing air monitoring results do not necessarily remain valid forever.

Exposure may change when an organisation:

• introduces new equipment

• changes a raw material or chemical

• modifies production methods

• increases production volumes

• changes ventilation or extraction systems

• moves work into a different area

• introduces new controls

• changes shift lengths or work patterns

• identifies deterioration in existing controls.

If previous monitoring no longer reflects how the work is actually being performed, further monitoring may be appropriate. The same principle applies following significant changes to control measures. Monitoring can help determine whether those controls are performing as intended.

5. When you need to know whether your controls are working

Air monitoring is not only about discovering a problem. It can also help verify whether controls are actually reducing exposure.

For example, a workplace may install local exhaust ventilation around a process that generates hazardous fumes. Air monitoring can help assess worker exposure after the control has been implemented and provide evidence about whether additional controls are required.

Safe Work Australia recommends that where air monitoring is required, it should generally be conducted after exposure controls have been implemented.

Monitoring can therefore answer an important WHS question:

Are our controls actually protecting workers to the extent we expect them to?

That is a different question from simply asking whether a control exists.

Exposure limits are changing in December 2026

Australian workplaces should also be aware of an important change taking effect later this year.

Until 30 November 2026, workplaces must continue to comply with Australia's existing Workplace Exposure Standards for Airborne Contaminants (WES).

From 1 December 2026, Australia will transition to the new Workplace Exposure Limits for Airborne Contaminants (WEL).

The terminology is important.

The change from "standard" to "limit" is intended to make it clearer that these values are limits that must not be exceeded, rather than recommended targets. A number of chemical exposure limits have also changed and new chemicals have been added.

For organisations where airborne contaminants are present, preparation should include identifying which contaminants are relevant to their operations and checking whether the applicable limit will change.

Existing monitoring data may also need to be reconsidered against the new limits.

Common situations where air monitoring may be needed

There is no single list of workplaces that automatically require air monitoring. The requirement depends on the contaminant, work being performed, existing information, controls and potential health risk. However, monitoring may commonly be relevant where workers are exposed to activities involving:

Crystalline silica

Cutting, grinding, drilling or processing silica-containing materials can create respirable crystalline silica dust.

Welding and hot work

Welding processes can generate complex mixtures of metal fumes and gases.

Diesel-powered equipment

Workers operating around diesel engines, particularly in enclosed or poorly ventilated environments, may be exposed to diesel engine emissions.

Solvents and volatile chemicals

Painting, cleaning, coating, degreasing and manufacturing processes can release hazardous vapours.

Dust-producing processes

Mining, quarrying, construction, manufacturing, woodworking and agricultural activities may generate airborne dust.

Lead work

Activities involving lead may create airborne dust or fumes. Safe Work Australia specifically states that worker exposure to airborne lead must be monitored where there is uncertainty about whether the exposure standard is or will be exceeded, or where monitoring is needed to determine whether there is a health risk.

These examples do not mean every worker performing these activities automatically requires personal monitoring. They do mean the potential for airborne exposure needs to be properly assessed.

Air monitoring is not the same as health monitoring

The terms air monitoring and health monitoring are sometimes confused, but they measure different things.

• Air monitoring measures contaminants in the workplace air and helps assess the exposure workers may experience.

• Health monitoring assesses a worker's health to identify changes that may be associated with exposure to particular hazardous chemicals.

For certain hazardous chemicals, a PCBU must provide health monitoring where exposure creates a significant risk to a worker's health and there are appropriate methods available to detect the effect of that exposure.

Depending on the hazard, a workplace may therefore require air monitoring, health monitoring, or both.

Neither should be treated as a substitute for controlling the hazard.

Who should conduct workplace air monitoring?

Air monitoring needs to be planned and interpreted correctly if its results are going to provide meaningful evidence. Safe Work Australia states that air monitoring should be conducted by a competent person, giving a certified occupational hygienist as an example.

An occupational hygienist can help determine:

• which contaminants need to be measured

• which workers or similar exposure groups should be sampled

• where and when sampling should occur

• whether short-term or full-shift measurements are appropriate

• what analytical methods should be used

• how the results compare with relevant exposure limits

• whether further monitoring or controls are needed.

Poorly designed monitoring may produce a number, but not necessarily a reliable picture of worker exposure.

What happens after air monitoring?

Air monitoring should lead to action, not simply another report stored away.

Depending on the findings, the workplace may need to:

1. review the relevant risk assessment

2. investigate the source of the exposure

3. improve existing controls

4. introduce additional higher-order controls

5. restrict access or modify work practices

6. review respiratory protective equipment

7. provide additional worker information or training

8. conduct further monitoring

9. consider whether health monitoring requirements apply.

Air monitoring can also identify differences between tasks, workers, shifts and locations that may otherwise be missed.

For example, overall exposure may appear low across most of a workplace while one particular task creates short periods of substantially higher exposure.

Understanding those variations can help an organisation target controls where they are needed most.

Don't wait until workers show symptoms

One of the biggest mistakes organisations can make is waiting for workers to report symptoms before investigating airborne exposure. Many occupational diseases develop gradually, and harmful contaminants cannot always be detected by sight or smell.

Air monitoring provides organisations with something much more useful: evidence.

It can help answer whether workers are being exposed, where that exposure is occurring, whether exposure limits are being met and whether existing controls are doing their job.

And where there is reasonable uncertainty about exposure levels or monitoring is necessary to determine whether there is a health risk, air monitoring is more than simply good practice — it may be a WHS requirement.

With Australia's new Workplace Exposure Limits taking effect from 1 December 2026, now is an appropriate time for organisations to review the airborne contaminants associated with their operations, check whether relevant exposure limits are changing and determine whether their existing exposure data is sufficient.

Ultimately, the objective should not simply be to demonstrate that a number falls below a limit. It should be to understand exposure well enough to prevent workers from being harmed in the first place.

WHS requirements vary between Australian jurisdictions and may include additional requirements for particular substances or industries. Organisations should check the requirements applying in their state or territory and seek competent occupational hygiene advice where necessary.

‍