Measurement of particulate matter in indoor environments

Compared to ambient air the particle size distribution of particulate matter (PM) in indoor air differs clearly. Regarding the observed grain sizes, the temporal resolution and the methods of measurements different dependencies of PM compared to ambient air are recognisable. In many cases the PM exposure situation in indoor air is dominated by typical indoor sources and activities. Particulate matter in ambient air additionally influences the PM exposure in indoor air depending on the kind of use, the site and the type of building. It has to be assumed that small air exchange rates, short distances to sources and sinks inside of buildings and, thus, different interaction and propagation mechanisms influence the PM release, distribution and deposition compared to known mechanisms in ambient air. This high variability complicates an evaluation of PM exposure in indoor air. PM exposure estimations via standardised gravimetric procedures for ambient air (PM10, PM2.5) are therefore inadequate for a survey of PM exposure in indoor air. In general these measurement techniques yield only small information about the correlation between different effects of sources and their impact on indoor air. Standardised measurement strategies for the determination of PM exposure in indoor air do not exist yet. Reproducible and comparable results which additionally identify interrelations between sources and effects are essential for the evaluation of PM exposure in indoor air. The present paper contains first orienting approaches concerning PM grain fractions in indoor air and the influence of given measurement conditions on the results of PM concentration measurements in indoor air.