In terms of the Regulations for Hazardous Chemical Substances of the Occupational Health and Safety Act, Regulation no. 6 (1), “Where the inhalation of an Hazardous Chemical Substance is concerned an employer shall ensure that a measurement program of the airborne concentrations is carried out…”

An air monitoring program is worked out once a Hazardous Chemical Risk Assessment has been carried out. One must be aware of what chemicals the workers are exposed to, the exposure weighting and the frequency. A product that is used once a year would be difficult to measure, while products used daily or weekly could be easily included into a measurement program.

Different products are absorbed on different media. It is therefore important that one knows exactly what one is testing for. A haphazard testing may be costly and give incomplete results.

Air monitoring is not only limited to chemical manufacturers or users of chemicals. A welding operation has often high exposure to metal fumes (which are classed as hazardous chemicals) while a weaving operation may have cotton dust as its problem. Printing inks often are Toluene / Xylene based products, which do require air monitoring and medical surveillance.

The frequency of monitoring is determined by the type of chemical to which the workers are being exposed. There are three tables in the Regulations for Hazardous Chemical Substances (see our talk no.4). Table 1 requires at least annual testing, while table 2 requires testing to be carried out once every 24 month. (Table 3 requires biological monitoring)

The purpose of the testing is to determine the exposure levels and if they are above the levels stipulated, to take corrective action. We recommend that when the levels are above half the permissible exposure levels, corrective action should be taken to reduce the levels to below half the levels. In all cases where we have been involved this was possible without any major problem.

Air monitoring should also be carried out on operations where the exposures are low, to act as proof in the future that all levels were well within the legal limits. A disgruntled employee may institute a claim against a company for damages done in the past. It is good to be able to show a court of law that the levels were always well within the limits stipulated.

The exposure levels are also used to work out a medical surveillance program for the workers. These medicals are of great importance (see our next talk) and must be part of the entire monitoring program.

Two products that need air monitoring but whose program differs are asbestos and lead. These two products will be discussed in greater detail in another Talk.

Written by Frans Wilbrink of Wilbrink & Associates, tel. 031 – 266 9035