Occurrence of dog, cat, and mite allergens in public transport vehicles

Background and Methods: Helsinki City Transport buses, trams, and undergrou nd trains carry 687 000 passengers on a weekday. Of the passengers, 0.13% t ravel with a pet. We interviewed passengers and measured allergen levels in vehicles to determine what difficulties allergens cause to passengers with allergy and asthma. Results: Of 2021 interviewed passengers, 14% complained about inconvenience caused by pets, usually health problems. Of 324 adult passengers with alle rgy or asthma, 53% had experienced symptoms in public transport; the corres ponding figure for 75 children was 32%. The median concentration of the mai n dog allergen, Can f 1, in dust from seats and floors in public transport vehicles was 2400 ng per g of dust (range 20-8500 ng/g). For the main cat a llergen, Fel d 1, the median was 870 ng/g (range 3-2600 ng/g). These levels can be regarded as low or moderate, and they cause symptoms in sensitive p ersons. Concentrations of mite allergens were undetectable or low. Allergen levels were lower in vehicles where pets were not allowed than in vehicles where pets were allowed, lower in dust from uncovered seats than in dust f rom seats with a covering, and lower after cleaning vehicle floors and seat s than before cleaning. Conclusions: Dog and cat allergens are present in public transport vehicles in Helsinki at levels that cause symptoms in sensitive persons. Prohibitin g pets would probably bring only a modest reduction in levels, as few pets are carried, and much allergen contamination comes from passengers' clothes .