Impact of dwelling characteristics on concentrations of bacteria, fungi, endotoxin and total inflammatory potential in settled dust

Abstract

Indoor air in homes contains a variety of organic agents such as bacteria, endotoxin and fungi. Epidemiological studies have shown links between these components and respiratory problems and the development of allergies.Twenty-eight dwellings located in the Greater Copenhagen area in Denmark were investigated in this study. Temperature, relative humidity and air exchange rate were measured. Dwelling characteristics including floor area, volume of the living room, floor material, year of construction of buildings and floor level were collected. The microbial exposure was measured by quantifying fungi, bacteria and endotoxin concentration in airborne dust collected by Electrostatic Dust fall Collectors (EDCs). The Total Inflammatory Potential (TIP) of the dust was also measured.Significantly higher concentrations of fungi were found in dwellings with high relative humidity (p = 0.03), larger room volume (p = 0.03) and in dwellings located on the second floor or higher (p = 0.02). Small floor area per person and low air exchange rate were significantly associated with increased concentrations of bacteria (both p < 0.01). Spring season (p = 0.01), buildings constructed before the 20th century (p = 0.09) and wooden floor (p = 0.03) were associated with high TIP.In conclusion, people living in smaller dwellings or in dwellings on upper floors are at higher risk of microbial exposure. While TIP was affected by some dwelling characteristics, it was mainly influenced by season.