DOMESTIC ALLERGENS IN PUBLIC PLACES-III - HOUSE-DUST MITE, CAT, DOG AND COCKROACH ALLERGENS IN BRITISH HOSPITALS

Background Exposure and sensitization to indoor allergens is a major c ause of asthma. Objectives This study investigated the levels of house dust mite, cat, dog and cockroach allergens in the dust and air in ho spitals and the effects of regular vacuum cleaning on allergen levels in hospital chairs. Methods Der p 1, Fel d 1, Can f 1 and Bla g 2 were measured in the dust collected by vacuuming upholstered chairs and a 1 m(2) area of carpet and mattress in 14 hospitals. Air samples were c ollected using an air sampler (flow rate 60 L/min) on 10 separate days for 4 h in the outpatient department in one of the hospitals during b usy clinics when patients were waiting for their appointments, In addi tion, dust samples were collected on four occasions, at 4-weekly inter vals, from 36 fabric covered chairs in the outpatient area of a busy c hest clinic by vacuuming each chair for 2 min. During the intervening weeks, 18 of the chairs (active group) were each cleaned by vacuuming for 1 min, three times per week. Der p 1, Fel d 1, Can f 1 and Bla g 2 were assayed using monoclonal antibody-based ELISA. Results In total, 83 carpets, 69 mattresses and 42 upholstered chairs were sampled. The levels of dust mite allergen Der p 1 and cockroach allergen Bla g 2 f ound in the hospital setting were low. High levels of Fel d 1 (GM 22.9 mu g/g, range 4.5-58) and Can f 1 (GM 21.6 mu g/g, range 4-63) were f ound in upholstered chairs. Airborne Can f 1 was detected on every occ asion (range 0.12-0.56 ng/m(3)), whilst detectable airborne Fel d 1 wa s found on 7 out of the 10 sampling days (range 0.09-0.22 ng/m(3)). De r p 1 and Bla g 2 were below the detection limit in all airborne sampl es. Following repeated vacuuming the mean cat and dog allergen levels decreased significantly (P < 0.001) and were almost fivefold lower in the vacuumed chairs compared with the control group. Conclusions Low l evels of mite allergen are unlikely to be of any clinical significance to mite-sensitive asthmatic patients. However, upholstered chairs in hospitals constitute a significant reservoir of cat and dog allergen. Inhalation of airborne allergen in patients attending their hospital a ppointment may exacerbate asthma in those highly allergic to cats or d ogs. These results question the wisdom of introducing soft furnishings and carpets into hospitals. Three-times weekly vacuuming significantl y reduces allergen levels in upholstered chairs.