Quantification of birch and grass pollen allergens in indoor air.

Birch and grass pollen grains as well as pollen-derived small particles appear as potent allergens in the outdoor air during spring and summer. The occurrence of pollen allergens in indoor air, however, has not been studied in depth due to lack of suitable sampling and analytical methods. Herein, a recently reported "direct on sampling filter estimation" (DOSAFE) technique (Acevedo et al., 1998) has been validated for quantification of pollen allergens in indoor air using two school rooms and two office rooms as experimental models. Using DOSAFE and polyclonal antibodies against water extracts of pollen from Betula pendula and Phleum pratense L, we found that indoor air of school and office rooms carried substantial amounts of pollen allergens, expressed as SQ units, predominantly occurring as particles with smaller diameters than the pollen grains. In one school room the indoor air birch pollen allergen concentrations increased from 242 to 403 SQ units/m3 over the sampling period although the corresponding outdoor air concentrations decreased from 350 to 90 SQ units/m3. Electrostatic air cleaning in one office room reduced its grass pollen allergen concentrations by more than 95% to 0.02-0.34 SQ units/m3 as compared to the control room.