An independent study, done in 2008 by the American College of Allergy, Asthma and Immunology, found that cat allergens may be present in homes that are cat-free.
It measured the quantity of cat allergen in mattress dust, and then analyzed the relationship between cat ownership and the level of cat allergen found in the participants’ homes.
Current cat owners’ homes had substantially higher amounts of allergens than past cat owners and those who had never owned a cat.
While never having a cat in the home led to a lower concentration of cat allergen, it didn’t protect against high cat allergen exposure in communities where cat ownership is common.
The researchers concluded that people who do not own cats may still be exposed to high levels of cat allergen in the home because cat ownership is common in their community and they bring the allergen home on their clothes.
Indoor smoking was also found to lead to higher level of cat allergens, possibly because cat allergens can bind to the smoking-related particulate matter, and consequently, allergen concentrations might be increased in settled dust.