Workplace air can be contaminated by a range of airborne contaminants that are hazardous when breathed in.
An average person can inhale more 3,000 litres of air over an eight hour working day. In conditions of hard physical work, up to 10,000 litres may be inhaled. In many workplaces, this air contains contaminants from work activities or processes.
Workplace air can be contaminated by a range of airborne contaminants that are hazardous when breathed in. Airborne contaminants may occur as vapours, dusts, particles, fibres, fumes or gases or combinations of these.
Contaminants can be released into the air when using hazardous chemicals or carrying out work processes such as those involving:
- rotating tools and parts, for example sanders, circular saws, routers, lathes, drills
- hot processes, for example furnaces, soldering, brazing, welding
- falling material (solids, liquids or powders), transferring powders, mixing
- spraying painting or abrasive blasting
- fracturing of solid material, for example, crushing rock
- abrasion, for example sanding, grinding, polishing, fettling
- cleaning and waste handling, for example sweeping or compressed air clean up.
Examples of airborne contaminants
Airborne contaminants can be produced by a wide range of processes or tasks in the workplace.
Table 1: Examples of some common airborne contaminants and their properties (Courtesy of the Health and Safety Authority (HSA)).
|Gas||Carbon monoxide and carbon dioxide|
|Vapour||Acetone, ethanol, chloroform, styrene, petrol|
|Fibres||Asbestos and glass|
|Mist||Solution being sprayed (e.g. paint, steam, electroplating baths)|
|Fume||Solder or welding fumes|
|Dust||Flour dust, concrete/cement dust (generated by grinding cutting, crushing, drilling etc.) and silica from stone cutting.|
The respiratory system can remove some contaminants through a series of defence mechanisms, but breathing in high levels of contaminants or low levels over a long period of time can overwhelm these defence mechanisms resulting in disease
Factors that influence the effects of contaminants include particle size, chemical composition, how much is in the air and the characteristics of the person (exposed to the contaminant).
Occupational exposure to certain airborne contaminants has the potential to cause or worsen a wide range of serious respiratory diseases including:
- cancers of the respiratory system
- chronic obstructive pulmonary disease (also called COPD)
Airborne contaminants can also cause health effects in other areas of the body including organs, eyes, nose, mouth and skin.
Workplace exposure standards
Workplace exposure standards are the legal maximum airborne concentrations of particular chemicals or substances to which workers may be exposed to in the workplace.
There are three types of exposure standards:
- Time-weighted average (TWA) is the maximum average airborne concentration of a substance when calculated over an eight hour working day, for a five day working week.
- Peak limitation is a maximum or peak airborne concentration of a substance determined over the shortest analytically practicable period of time which does not exceed 15 minutes.
- Short term exposure limit (STEL) is the time-weighted average maximum airborne concentration of a substance calculated over a 15 minute period.
Safe Work Australia publishes the workplace exposure standards for Australia. Guidance on interpreting exposure standards is available in Safe Work Australia's Guidance on the Interpretation of Workplace Exposure Standards for Airborne Contaminants.
Note: Exposure standards are not designed to protect all workers and some workers may show health effects at levels that are below the exposure standard. It is important to remember that even if a substance does not have a published exposure standard, such as diesel particulate matter (DPM), it can still be harmful to health. Controls should therefore be used to minimise worker exposure to airborne contaminants so far as is reasonably practicable.
A competent person such as occupational hygienist can carry out personal air monitoring.
When identifying possible airborne contaminants in the work environment, look at tasks and/or processes, and technical information sources.
Technical information sources include:
- product labels
- safety data sheets (SDS) - sections 2 and 8
- equipment operation/user manuals
- plant and product suppliers
- Managing risks of hazardous chemicals in the workplace Code of practice 2013 (PDF, 1.46 MB)
Hazard specific guidance is available for the following:
- Abrasive blasting
- Biological hazards
- Construction dust – respirable crystalline silica
- Spray painting
Control the risks
Reducing the airborne concentration of a contaminant is more effective than simply relying on respiratory protective equipment (RPE). Look carefully at the control measures that can be used, some are more cost effective and practical for each situation than others.
Stop or reduce exposure to contaminants
Eliminate the use of a harmful product or substance and use a safer one.
- Use a safer form of the product, (e.g. paste rather than powder).
- Modify the work process to generate or emit less of the substance.
Control the exposures
Local exhaust ventilation
Capture the contaminant at or near the source using local exhaust ventilation (LEV). Examples include on-tool extraction, fume cabinets and spray booths.
- Water or fine mist suppression can also be used to control dusts when LEV is not suitable. However, it needs to be used correctly. This means supplying sufficient water or fine mist volume and flow the entire time, just wetting the material beforehand won't control dust generated during a work process.
- Locate work processes outdoors or as far away from other workers where possible.
- Enclose the work process or substance so that the contaminant does not escape.
Respiratory protective equipment (RPE)
RPE does not prevent or control contaminants from becoming airborne. It should be used as a last resort and not as the primary means of control, but rather in combination with higher order controls such as LEV or water suppression. It is important to choose the right respirator for the job.
Combining control measures
Using a combination of controls measures will usually be more effective than relying on just one. Table 2 below provides some examples.
Table 2: Examples of control measures
|Cleaning with solvent on a rag||
Use a rag holder.|
Wear protective gloves.
Provide a small bin with a lid for used rags.
Avoid skin contact.
Reduce solvent vapour from used rags.
|Dust and sparks from abrasive wheel||
Use dust extraction/local exhaust ventilation.|
|Fume from cutting demolition scrap||
Wear a powered air purifying respirator (PAPR) welding helmet and gloves.|
Work outdoors upwind of the fume wherever possible.
Allow the fume to clear before removing helmet.
|Cutting-fluid mist from a lathe and/or swarf||
Put an enclosure around the lathe and extract the air to a safe place.|
Use protective gloves.
|Dust from disc cutter used on stone benchtops||
Use water suppression or dust extraction/local exhaust ventilation (fitted to an H-class vacuum or dust-extraction unit).|
Isolate the work from others.
Vacuum (using an H-class industrial vacuum) or wet-wipe any residual dust from surfaces.
When working with airborne contaminants, train workers in:
- the types of airborne contaminants likely to be present in the workplace and the harm they can cause
- what controls are used to prevent exposure and how to use them.
Maintaining and reviewing the controls
You may already have the right controls in place, but are they all working properly?
- When were the controls last checked?
- Are controls used by workers when needed?
- Is there a better control that could be used?
A competent person such as an occupational hygienist should carry out personal air monitoring of workers to check that control measures are working.
Controls must be reviewed at least once every five years or earlier in certain situations. Refer to section 5.2 of the Managing risks of hazardous chemicals in the workplace Code of practice 2013 (PDF, 1.46 MB) for more information on when control measures need to be reviewed.
Health monitoring can be used to identify changes in a person's health and must be conducted when there is a significant risk to health because of exposure to an airborne contaminant.
Read more about airborne contaminants that require health monitoring.
Codes of practice
- Abrasive blasting Code of Practice 2021 (PDF, 1.14 MB)
- Foundry (PDF, 0.71 MB)
- Managing risks of hazardous chemicals in the workplace Code of practice 2021 (PDF, 1.24 MB)
- Spray painting and powder coating Code of Practice 2021 (PDF, 1.2 MB)
- Welding processes Code of Practice 2021 (PDF, 0.96 MB)
- Managing respirable dust hazards in coal-fired power stations Code of Practice 2018 (PDF, 1.2 MB)( PDF, 1065.89 KB)
WHSQ hazard specific guidance and information
- Abrasive blasting
- Biological hazards
- Construction dust – respirable crystalline silica
- Health monitoring
- Skin exposure
- Spray painting.