Effect of Air Flow Rates in Versatrap Slit Impactor Cassettes on the Collection of Atmospheric Mold Spores in a Rural Community

Exposure to mold allergens including mold spores and hyphal fragments are associated with allergic sensitization which is a risk factor for asthma in a community. Smaller aerodynamic size of spores (åµm) allows them to penetrate and settle in the lower airways and produce damaging byproducts (allergens, glucans, mycotoxins, and other immunomodulators). Usually mold spores in ambient atmosphere are collected by impactors in air monitoring stations and in most cases these impactors are operated in a single standard air flow rate. However, sampling efficiency of an impactor can change in different air flow rates and since spore aerodynamic sizes vary a lot and temperature and humidity of ambient air can influence aerodynamic properties of airborne mold spores in the atmosphere, we hypothesize that mold data acquired based on a single air sampling flow rate ‰ÛÒ as currently being reported by most ambient air monitoring stations in the United States - could be incomplete. In this study, we have collected atmospheric molds spores simultaneously at three different air flow rates (5L, 10L, and 15L per minute) and samples were collected from four ambient locations in Statesboro, Georgia in different days with different climatic conditions. Spores were collected by the VersaTrapå¨ spore trap cassettes, which provide the sampling versatility to capture mold spores of wide size range from 1.5 to 3.9 åµm. The narrow slit inlet of the VersaTrapå¨ focuses particles toward the clear glass slide coated with a sticky substrate. As hypothesized, we found a substantial difference between spore concentrations collected at different air flow rates: 1306 å± 960, 1709 å± 1430, 1081 å± 923 spores/m3 at 5L, 10L, and 15L per minute (for one hour). We also found diurnal variations of spore concentrations at different times of the day and maximum spore concentration levels were observed between late afternoon and evening.