AIRBORNE CAT ALLERGEN (FEL-D-I) - ENVIRONMENTAL-CONTROL WITH THE CAT INSITU

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-mu-m 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-mu-g/day Fel d I compared with approximately 0.5-mu-g/day Fel d I. In keeping with this air filtration was effective at cleaning the air only if (1) there was no carpet and (2) the floor was cleaned first. The results show that airborne cat allergen can be dramatically reduced by a combination of washing the cat, reducing furnishings, vacuum cleaning, and air filtration. Comparison with previous results suggests that the reductions achieved may be sufficient to allow a cat-sensitive patient to live safely in the same house as a cat.