Figure 1: Qualified occupational hygienists at work

There are three routes through which exposure to substance in workplace can occur: inhalation, absorption to skin and ingestion. Our body’s responses to this exposure depends on multiple factors such as the nature and concentration of the substance, its health implications and a person’s biological resistance, the amount time exposed to the substance and amount of the substance absorbed by the body and most importantly, the effectiveness of controls in the workplace. Serious health effects can occur immediately or it may take years before health symptoms appear.


   Figure 2: Potential health implications involved

An estimation made by Cancer Council indicates that occupational exposure to carcinogens cause around 5,000 new cancer cases every year in Australia and approximately 3.6 million of Australian could be exposed to one or more carcinogens at work. A larger number of people have been permanently disabled or have had their quality of life impaired due to work-related exposures to hazardous substances. This leads to huge financial losses which are incurred by employers from the burden of work related disease of their employees. The good news is that all these steep costs can easily be avoided through low cost measures. This is true for many industries such as transport, postal & warehouse, construction, agriculture, forestry and fishing, electricity, gas and water services, manufacturing and the list goes on.

Exposure standard relates to the airborne concentration of a particular substance that must not be exceeded. It establishes a statutory maximum upper limit and must not be considered as an acceptable level of exposure to workers. In Australia, it is a legal obligation to comply with Sections 17 and 19 of the WHS Act to eliminate risks associated with these hazardous substances completely or if not possible, to keep them as low as possible.

There are three types of Exposure Standards:

  • 8-hour time-weighted average (TWA) which is the average airborne concentration of a substance to which a worker is exposed using a baseline of an eight-hour working day and 5-day a working week. This is the most popular type of Exposure Standard.
  • Short term exposure limit (STEL) which is the time-weighted maximum average airborne concentration of a substance permitted over a 15-minute period. STELs are recommended in places where there is proof that negative health effects caused by short term exposure and they are aimed to minimise risks of intolerable irritation, irreversible tissue change, narcosis to an extent that could lead to workplace incidents
  • Peak limitation is the maximum airborne concentration of a substance which is determined over the shortest analytical period of time that does not exceed 15 minutes. This exposure standard must not be exceeded at any time.

Employers should ensure primarily that:

  • employees and other people are not exposed to health and safety risks emerging from the business
  • they manage risks under WHS regulations linked with using, handling and storing hazardous chemicals safely, airborne contaminants and asbestos.
  • No worker is exposed to a substance that exceeds the exposure standard
  • Air monitoring is conducted to determine the airborne concentration of a substance at the workplace or if uncertain that whether or not the concentration of air contaminant has been exceeded.
  • Exposure standard for asbestos is not exceeded at the workplace.

It is recommendable to carry out air monitoring for a number of important reasons:

  • Select the best exposure minimisation controls
  • Ensure if existing controls are working efficiently
  • Choose the right quantity of respiratory and personal protective equipment if other controls do not sufficiently eliminate or minimise risks at workplace
  • Checking exposure level after a particular process or production method has been changed
  • Investigating complaints from workers
  • Determine if they have been exposed to or are currently being exposed to hazardous chemicals

Find out how Anitech can help your business with Measurement of Hazardous Substances.


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