The level of submicron fungal fragments in homes with asthmatic children

Abstract

Objectives: Much scientific evidence indicates a positive association between moldy environments and respiratory illnesses and/or symptoms (e.g., asthma). Recently, submicron fungal fragments (<1.0 μm) have been suggested as a potential contributor to adverse health effects due to their biological composition (e.g., antigens, mycotoxins, and (1,3)-β-D-glucan) as well as their small size. However, the contribution of exposure to fine fungal particles on adverse health outcomes has been poorly characterized, particularly in homes with asthmatic children. We characterized the airborne level of smaller-sized fungal particles between homes with and without asthmatic children.

Methods: We visited 29 homes with (n=15) and without (n=14) an asthmatic child and sampled submicron fungal fragments in a living room and child׳s bedroom, along with outdoor sampling, using the NIOSH two-stage sampler. (1,3)-β-D-glucan of fungal fragments analyzed by Limulus Amebocyte lysate assay (LAL) was used for quantifying their exposure.

Results: Overall, the geometric mean (GM) concentration of (1,3)-β-D-glucan in submicron fungal fragments in indoor air was two-fold higher in homes with asthmatic children (50.9 pg/m(3)) compared to homes with non-asthmatic children (26.7 pg/m(3)) (P<0.001). The GM concentration of these particles in child׳s bedroom in homes with an asthmatic child (66.1 pg/m(3)) was about three times higher than that in homes with non-asthmatic children (23.0 pg/m(3)) (P<0.001). The relative humidity had a negative correlation with the concentration of (1,3)-β-D-glucan in submicron fungal fragments (Pearson coefficient=-0.257, P=0.046).

Conclusions: Our findings indicate that homes with asthmatic children have a higher concentration of submicron fungal fragments compared to homes with non-asthmatic children. A greater exposure to smaller-sized fungal particles may occur in homes with an asthmatic child as relative humidity decreases. The very careful control of relative humidity in indoor air is necessary for reducing exposure to fine fungal particles and inhibiting the growth of microorganisms in homes with allergic diseases.

Keywords: Bioaerosols; Childhood asthmatics; Fine particles; Fungal fragments; Mold exposure.