A team of researchers have analyzed more than 3,500 samples of dust from homes in 22 sites across Europe, and have observed that there is a large qualitative and quantitative differences of house dust mite allergen levels in Europe, which can partly be explained by geographic and housing characteristics. They have identified four factors which may likely influence the levels of allergy-causing dust mite in a bedroom:

• How old is the mattress?


• On which floor is the bedroom located?


• How good is the ventilation?


• Is it damp?

They suggested that "mite allergen exposure may be reduced by replacing the mattress regularly and increasing ventilation of the bedroom, particularly in winter". Although the survey was made on homes across countries in Europe, I can also imagine the same would apply in US homes (and elsewhere), where dust mites has been found in detectable levels in most homes. An oldish study published in 2001 indicated that the levels of dust mites in US homes where higher in older homes, non-West census regions, single-family homes, no resident children, lower household income, heating sources other than forced air, musty or mildew odor, and higher bedroom humidity.

[Photo: AAAAI]