MITE ALLERGEN (DER-P-1) CONCENTRATION IN HOUSES AND ITS RELATION TO THE PRESENCE AND SEVERITY OF ASTHMA IN A POPULATION OF SYDNEY SCHOOLCHILDREN

House dust mite (HDM) allergen exposure and its relation to HDM allerg y and asthma was assessed BE a case-control study conducted over three seasons in 74 Sydney schoolchildren, 33 of whom were allergic to HDM and 12 of whom had current asthma. In each season, histamine inhalatio n tests and skin prick tests were performed, symptom questionnaires we re administered, and dust samples were collected. The mean concentrati ons of HDM allergen (in micrograms of Der p I PEI. gram of fine dust) were: bed, 38.9 (95% confidence interval [CI] 31.8 to 47.5); bedroom f loor; 22.4 (95% CI, 18.3 to 27.5); nod lounge room floor; 13.7 (95% CI , 10.7 to 17.6). The mean of the highest allergen concentration in eac h house was 51.0 (95% CI, 43.2 to 60.1). All brit two subjects had at least one site in all seasons within HDM allergen concentration greate r than 10 mu g/gm, the proposed threshold for asthma symptoms. Subject s with allergy to HDM, symptoms of asthma, or airway hyperresponsivene ss did not have higher HDM allergen concentrations in their houses. In this study we were unable to test hypotheses concerning proposed thre sholds for risk of sensitization and for risk of asthma symptoms becau se virtually all subjects were exposed to HDM allergen levels above th e proposed thresholds.