Appropriate Sampling Strategies for the Measurement of Formaldehyde in Indoor Air

Abstract

Active and passive sampling methods are available for the determination of maximum formaldehyde concentrations and average formaldehyde concentrations respectively. The present work compares the performance of an active cartridge type sampler with an impinger method and a diffusive monitor which have previously been used at the Building Research Establishment. Good agreement between the three methods was found in a comparison at two formaldehyde concentration levels. The sampling strategy required to obtain a representative reading of the formaldehyde concentration in an indoor atmosphere was investigated using a commercially available diffusive sampler. An investigation of spatial variation in five rooms suggests that sampling in one location should give a representative reading of the formaldehyde concentration in a room, providing the sampler is not placed near a major source of formaldehyde. An initial investigation of temporal variation in six rooms found that one three day sampling period was sufficient to obtain a representative reading of the mean monthly formaldehyde concentration. Between month variation was found to be higher than within month variation although no strong seasonal effects were observed. The results suggest that more than one three day sampling period should be used to estimate the annual mean formaldehyde concentration and two measurements (summer and winter) may be a reasonable approach. Further work in a larger number of homes is in hand to verify the effectiveness of this sampling strategy.