Ubiquitous presence of cat allergen in cat-free buildings: probable dispersal from human clothing.

Fel d I has been found in almost all houses investigated, including those in which cats have never been present. These observations have not been explained. We measured Fel dI in samples of carpet dust from ten newly built model homes, 14 occupied homes, six allergists' offices, five hospital corridors, and three shopping mall stores. We also measured Fel d I on T-shirts of persons with and without cats. Measurable amounts of Fel d I were found in all the dust samples. Fel d I found in older model homes exceeded that found in newer model homes (P < .05). The amounts of Fel d I found in allergists' offices, hospital corridors, and retail stores were similar to the amounts found in occupied homes without cats. Fel d I was found in all T-shirts sampled and increased with increasing exposure to cats. Our findings confirm and extend previous reports of the ubiquitous presence of cat allergen and are consistent with the hypothesis that Fel d I is carried into cat-free buildings on the clothing of people exposed to cats.