Allergen avoidance in a day-care center.

The predominant sensitizing allergens in Swedish asthmatic children are furred pet animals. Poor ventilation and increased indoor humidity cause accumulation of pet allergens indoors. Indirect contacts with cats also increase pet allergen exposure. We investigated whether the concentration and the total amount of cat (Fel d I) and dog (Can f I) allergen in dust from various surfaces in a day-care center were influenced by extensive renovation, installation of a new ventilation system, ventilation of floors, and avoidance by families and personnel of direct and indirect contacts with pets. The cleaning routine in the day-care center was changed extensively after renovation. Old mattresses, pillowcases, curtains, sofas, and soft toys were removed, and new material were purchased. Dust was collected from various surfaces before and after renovation from table and chair surfaces, floors, curtains, mattresses, pillows, cushion-like toys, and sofas on five occasions during a 12-month period. Fel d I and Can f I allergen levels were determined by sandwich ELISA. The reduction in the total amount of both Fel d I and Can f I/sampling area was more pronounced than the reduction in the concentration of allergen/g of dust. After renovation, the mean cat and dog allergen concentration was decreased by six and 10 times, respectively. After 1 year, the total amount of cat allergen was lower in all areas (from 24 ng to < 1 ng/sampling area, P < 0.05). Already at the first sampling after renovation, the total amount of dog allergen had decreased more than 10 times. In a previous study, we found the median concentration of cat and dog allergen to be 10-30 times higher in ordinary day-care centers. Our present study demonstrates that children changing from a normal center to the renovated center would be exposed to much lower levels of cat and dog allergen. Combined measures such as installation of mechanical ventilation, ventilated floors, regular extensive cleaning, and, probably most important, avoidance of direct and indirect contacts with pets, should decrease cat and dog allergen exposure in day-care centers.