RR923 - Investigation of relationship between saturated vapour concentration and real exposure to vapour

Quantitative risk assessment is a key component of chemical approval schemes. This study was designed to provide information to better assess levels of risk and the potential for human exposure to low volatility chemical substances. The approach taken was to investigate the relationship between the fundamental physiochemical property of saturated vapour concentration (SVC) and measured airborne concentrations of such substances and to carry out baseline testing under different experimental and simulated work conditions. The results of these tests indicate that, whilst SVC may provide a reasonable estimate of the maximum possible concentration of any given compound and/or the relative ratios of different compounds, for chemical compounds of low volatility real airborne concentrations are considerably lower (generally less than 1% of SVC). Consequently, SVC significantly over-estimates airborne concentrations of these low volatility substances in the workplace and hence we conclude that it is not an accurate indicator of the likely risk of airborne exposure. Although the scope of the tests carried out in this project was very limited, it is apparent that the airborne concentration, and hence the potential for exposure by inhalation, is probably more dependent on the nature of the task being undertaken or usage of the compound than on the SVC.

This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE policy.

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Updated 2021-04-23