Airborne birch and grass pollen allergens in street-level shops

Polluted urban outdoor air may be enriched with large amounts of submicronic respirable pollen allergen particles that penetrate into street-level shops. The objectives of the study were to map concentrations of birch and grass pollen allergens in indoor air of street-level shops and to explore the effect of electrostatic air cleaning under authentic working conditions, indoor air samples were collected in May and July 1999 in two shops. Allergens were quantified by a direct on sampling filter in solution (DOSIS) luminescence immunoassay. The average concentration of airborne indoor birch pollen allergen in the shop with air cleaning was estimated to be 20 +/- 9 SQ/m3 (mean +/- SD) compared to 31 +/- 17 SQ/m3 (mean +/- SD) of that without. The air cleaner reduced the indoor air birch pollen allergen concentration by on average 26 to 48% (P < 0.05). Corresponding figures for airborne indoor grass pollen allergen concentrations were 14 +/- 7 SQ/m3 and 17 +/- 8 SQ/m3, indicating a statistically non-significant (t-test) average 18% reduction of allergen by air cleaning. Excluding two observations with poor fit to the statistical model a significant (P < 0.05) average 27% reduction was obtained. Substantial amounts of airborne birch and grass pollen allergens may occur in street-level shops during flowering seasons.