Background Allergen and fungal exposures are important risk factors for asthma. We conducted a longitudinal analysis of allergen levels in Melbourne homes between 1996 and 1998 to examine the effects of changing residential characteristics on allergen and fungal levels. We also examined the changes in levels of indoor allergens.
Methods The subjects were participants in the European Community Respiratory Health Survey (ECRHS) in Melbourne. In 1996, 485 subjects participated in a follow-up study, which involved both home and laboratory visits. Dust and air samples were collected from participants' bedrooms and a validated residential questionnaire was administered. In 1998, 360 participants underwent further follow-up. House dust mite (Der p 1) and cat allergens (Fel d 1) and ergosterol were measured in dust.
Results We observed moderate within home correlations between 1996 and 1998 in floor Der p 1 (intraclass correlation ICC=0.48), bed Der p 1 (ICC=0.61), Fel d 1 (κ=0.53) and ergosterol (ICC=0.28) levels. We found that the floor Der p 1 levels decreased from 1996 to 1998 in the homes of participants who moved to an attached home, moved their bedrooms to the first floor, removed fitted carpet or central heating. Replacing or vacuuming the mattress more than twice per year reduced levels of Der p 1 in the bed. Ergosterol levels were reduced by removing visible mould and fitted carpet.
Conclusions These findings provide evidence to support current advice with regard to allergen avoidance in patients with dust mite and fungal allergies.