APPROPRIATE SAMPLING STRATEGIES FOR THE MEASUREMENT OF FORMALDEHYDE IN INDOOR AIR

Active and passive sampling methods are available for the determinatio n of maximum formaldehyde concentrations and average formaldehyde conc entrations respectively. The present work compares the performance of an active cartridge type sampler with an impinger method and a diffusi ve monitor which have previously been used at the Building Research Es tablishment. Good agreement between the three methods was found in a c omparison at two formaldehyde concentration levels. The sampling strat egy required to obtain a representative reading of the formaldehyde co ncentration in an indoor atmosphere was investigated using a commercia lly available diffusive sampler. An investigation of spatial variation in five rooms suggests that sampling in one location should give a re presentative reading of the formaldehyde concentration in a room, prov iding the sampler is not placed near a major source of formaldehyde. A n initial investigation of temporal variation in six rooms found that one three day sampling period was sufficient to obtain a representativ e reading of the mean monthly formaldehyde concentration. Between mont h variation was found to be higher than within month variation althoug h no strong seasonal effects were observed. The results suggest that m ore than one three day sampling period should be used to estimate the annual mean formaldehyde concentration and two measurements (summer an d winter) may be a reasonable approach. Further work in a larger numbe r of homes is in hand to verify the effectiveness of this sampling str ategy.