Continuous monitoring of air impurities in dwellings

Continuous monitoring of radon, air ions, CO2, and aerosol particles was carried out over one-week periods in 19 dwellings in the Tampere area of Finland. In addition, time-averaged particle mass concentrations in two-size fractions were measured, and concentrations of certain organic gases and vapours were determined from short-time samples, as was the formaldehyde concentration in a few locations. In general, measured concentrations were relatively low irrespective of the location and despite the fact that the air exchange rates in small houses were usually found to be below 0.5 h-1. This clearly is due to the relatively clean air in the suburban areas and the lack of important indoor impurity sources. Where the impurity sources were enhanced, the concentrations were also substantially higher. This was observed in high bedroom CO2 concentrations and high radon concentrations in some locations. Also, the average radon concentration (370 Bq/m3) was relatively high. This reflects the large fraction of small houses of all studied locations. Tobacco smoke was the only source producing particle concentrations that can be regarded as significant