Airborne cat allergen (Fel d I). Environmental control with the cat in situ.

In a house with a cat furnishings, air-exchange rate, and the cat are all thought to influence airborne cat allergen. We carried out experiments using two separate rooms, modifying the environment, applying different cleaning techniques, and washing the cat, to analyze these sources and to design methods of reducing airborne allergen. Airborne measurements were made with a cascade impactor and a two-site monoclonal antibody-based immunometric assay for cat allergen Fel d I. Within 30 min of entering a 30-m3 clean room the cat itself was found to increase airborne Fel d I by 30 to 90 ng/m3. Following serial weekly washing of the cat this increase was reduced to less than or equal to 7 ng/m3, with a more marked fall in small particles (less than or equal to 2.5 microns diameter) from 9.5 to less than or equal to 0.4 ng/m3. To study the influence of the room design we kept the cat in a room of 33 m3 for 20 h/day and modified the room. This room was studied with or without furnishings and with air-exchange rates of 0.2 or 2.4 air changes per hour. Both low ventilation rate and furnishings increased the level of Fel d I measured 1 h after the cat was removed. However, the most striking finding was that the carpet accumulates cat allergen at approximately 100 times the level for a polished floor, that is, approximately 100 micrograms/day Fel d I compared with approximately 0.5 micrograms/day Fel d I.(ABSTRACT TRUNCATED AT 250 WORDS)