Airborne contaminants can be generated through the use of hazardous chemicals or various workplace activities.
Workplace activities can produce dusts, gases, fumes, vapours, fibres, or mists. Although these contaminants are often invisible, they can pose significant health and safety risks.
Gases exist entirely in a gaseous state at normal temperature and pressure. When liquids or solids transition to a gaseous phase, the resulting state is called a vapour. Smoke consists of fine solid particles resulting from incomplete combustion. Fumes are tiny airborne particles generated when a solid vaporises and then condenses, such as during welding.
Various workplace processes and equipment can generate airborne contaminants that may be harmful to health. Common examples include:
- welding produces fumes and other hazardous by-products
- truck engines can emit diesel exhaust fumes
- grinding metal can release toxic dust or fumes
- manufacturing wood products may expose workers to solvent vapours from adhesives.
How workers are exposed
Exposure to hazardous substances can occur through inhalation, skin absorption, or ingestion.
Inhalation of vapours, dusts, fumes, or gases is the most common route of exposure. However, for certain chemicals, skin absorption can also be a significant route of exposure.
How workers are affected
The way the body reacts to hazardous substances and mixtures depends on:
- the physical and chemical properties of the substance
- the health effects it can cause
- the quantity of the substance or mixture that the body absorbs.
Individuals metabolise chemicals differently, meaning the health impact can vary from person to person.
The level of exposure is determined by:
- the airborne concentration of the substance or mixture
- the duration of exposure
- the effectiveness of risk controls.
Some substances and mixtures produce immediate health effects, while others may take decades for symptoms to become apparent.
Example: Welding
Welding serves as a useful example to illustrate what airborne contaminants are, how they are generated, and the health effects they can have.
The welding process can produce fumes, mists, dust, vapours and gases. The quantity and composition of these contaminants vary considerably based on the welding method and the materials involved, including metals, solvents, flux, paint and plastics.
Exposure to welding fumes can result in a range of health conditions, including upper respiratory tract irritation, chest tightness, asphyxiation, asthma, wheezing, metal fume fever, lung damage, bronchitis, cancer, pneumonia, and emphysema.
While some welding fumes are visible, many contaminants — including fumes, mists, dust, vapours and gases are invisible.
Control measures
Under the work health and safety laws, there are specific requirements to manage risks arising from exposure to chemicals.
Safe Work Australia guidance material provides the recommended approach for managing these risks. Refer to the workplace exposure standards (WES) section below for further details.
As a person conducting a business or undertaking (PCBU) you are required to:
- manage risks associated with using, handling and storing hazardous chemicals safely, including airborne contaminants
- ensure that no worker is exposed to airborne concentrations of any substance or mixture that exceed the applicable WES
- ensure air monitoring is carried out to determine the airborne concentration of a substance or mixture at the workplace to which a WES applies
- ensure air monitoring results are recorded, retained for 30 years, and readily accessible to anyone at your workplace who may be exposed to the substance or mixture.
Workplace exposure standards
WES state airborne concentrations of a particular substance or mixture that must not be exceeded. There are three types of WES:
- 8-hour time-weighted average: the average airborne concentration of a substance that is acceptable over an 8-hour workday and a standard 5-day working week
- peak limitation: a maximum or peak airborne concentration of a particular substance determined over the shortest analytically practicable period of time, which does not exceed 15 minutes
- short-term exposure limit: the time-weighted maximum average airborne concentration of a particular substance permitted over a 15-minute period.
WES are based on the airborne concentrations of individual substances. It should not cause adverse health effects or discomfort to workers.
A full list of chemicals with WES can be found in Safe Work Australia’s Workplace exposure standards for airborne contaminants.