Exposure assessment of indoor allergens, endotoxin, and airborne fungi for homes in southern Taiwan.

This study was undertaken to examine the seasonal variations of domestic Der p 1, Der p 2, and endotoxin on mattress and airborne fungal concentrations in homes of asthmatic and nonasthmatic children in southern Taiwan, where temperature and relative humidity are usually high throughout the year. A group of asthmatic children (10-12 years old) were selected randomly based on a citywide questionnaire survey. The nonasthmatic children were chosen to be in the comparison group by matching in age, gender, and proximity of residence. Environmental sampling of domestic microbes was conducted once a month for a year. Twelve calendar months were grouped into spring, summer, fall, and winter according to weather data (mainly average temperature and humidity) from the Central Weather Bureau. Dust samples from a child's mattress and airborne samples from a child's bedroom were collected and analyzed for allergens of Der p 1 and Der p 2, endotoxin, and fungi respectively. Results show that about 65% of children's mattresses in our region have Der p 1 levels greater than 2 microg/g. It is also apparent that most airborne fungal concentrations found in homes of either asthmatic or nonasthmatic children are higher than the recommended levels of concern. The predominant genera are Cladosporium, Aspergillus, Penicillium, Alternaria, and yeast. In addition, seasonal effects seem to be a critical factor for the concentrations and distributions of domestic endotoxin in these study homes. The implication of long-term exposure to these high levels of environmental microbes and how their effects vary with seasons remain to be further characterized.