New workplace exposure limits for airborne contaminants

Work health and safety ministers have agreed to a new workplace exposure limit list for airborne contaminants and a harmonised transition period, which will end on 30 November 2026.

The workplace exposure limits will replace the current workplace exposure standards, after the ministers agreed to rename them to make it clear that a limit should not be exceeded, and for Australia to align with terms used internationally.

While most exposure limits remained unchanged, the workplace exposure standards review did result in some changes, including reductions and increases in limits for certain chemicals and the removal or introduction of new limits for others.

An airborne contaminant is a fume, mist, gas, vapour, or dust that can be harmful to health when breathed in. They may not be visible to the naked eye nor detected by odour, and they may arise from chemicals or materials used in the workplace or be generated by work processes.

Safe Work Australia’s Workplace exposure limits for airborne contaminants list notes that some people may have health effects at levels below the exposure limit, either due to individual differences or due to existing health conditions (such as pregnancy, cancer treatment, recovery from an illness, heart, or lung disease).

There may be additional factors that can cause people to have health effects at an exposure level below the workplace exposure limit. If there are multiple airborne contaminants in the workplace, then the combined effects of these must be considered.

For example, exposure to multiple airborne contaminants, either at the same time or one after the other, may cause additional harm. Some airborne contaminants can also interact to be more harmful than either contaminant on its own.

Airborne contaminants that can also be absorbed through the skin can increase a worker’s exposure and, in some cases, cause sensitisation.

Safe Work Australia said PCBUs should also engage an appropriately trained and experienced professional, such as an occupational hygienist, to understand the potential effect on workers’ health of airborne contaminants in their workplace and identify the control measures that may be needed to protect workers.

The list notes that there are three different kinds of exposure limits: an 8-hour time weighted average (TWA), short-term exposure limit (STEL), and peak limitation.

The TWA is the maximum average concentration of an airborne contaminant calculated for an eight-hour working day, based on a 5-day working week (40 hours). A worker must not be exposed to a level above the TWA over the course of an 8-hour working day.

A STEL is the time-weighted average maximum concentration of an airborne contaminant calculated over a 15-minute period. It is intended to protect most workers from the acute effects of exposure.

A peak limitation is the maximum or peak concentration of an airborne contaminant measured over the shortest time possible, and not exceeding 15 minutes. Exposure above the peak limitation can cause immediate and severe health effects, even if the exposure is very short. Exposure above the peak limitation is not allowed at any time.