Analysis of Settled Dust in Homes and Fungal Glucan in Air Particulate Collected during HEPA Vacuuming

Abstract

Six occupied single-family dwellings in Ottawa, Canada were subjected to weekly or bi-weekly professional cleaning using a HEPA filter-equipped vacuum cleaner and following a strict cleaning protocol based on floor area and type of floor. Sieved weights of dust were collected from each cleaning. Statistically significant reductions of fine dust loading occurred only after four sequential cleanings. As dust loading of the floor was reduced, exposure to dust mite allergens, endotoxins, and fungal glucans in dust decreased. During the first cleaning (when loadings were highest), airborne particles were collected using a MOUDI sampler (0.18—18 μm size fractions). The fungal polysaccharide β-(1, 3)-D-glucan was present in approximately equal proportions in each size fraction. This demonstrates that the majority of the fungal exposure was not to intact spores, but to fungal fragments much smaller than spores that have greater efficiency of deeper penetration into the lungs. This study also shows the importance of ensuring that cleaning interventions are effective before they can be related to health outcomes.