Measurements of saturation vapour pressure for estimating biocide concentrations in indoor air

The vapour pressure is an important parameter for estimating the fate of chemicals in the indoor environment. For compounds of low volatility, a combination of the Knudsen effusion method and the Langmuir free evaporation method enables the precise measurement of vapour pressures over a wide temperature range. This is demonstrated for the compounds dichlofluanid, tolylfluanid and alpha-endosulfan. Saturation concentrations were estimated and compared with results from test chamber experiments carried out under indoor conditons.