Indoor biological exposures : what can HVAC filter dust tell us?

Because people in the US spend an estimated 80-90% of their time indoors, much of it at home, understanding the potential health impacts of biological exposures that occur in the home is crucial. Recently, rapid advances in high-throughput DNA sequencing technology have spurred increased study of the relationships between the human and built environment microbiomes. HVAC filters hold promise as long-term, spatially integrated, high volume samplers to characterize the airborne home microbiome. In order to optimize HVAC sampling protocols and improve comparability between studies employing HVAC filters for bacterial community analysis, three HVAC filter dust sampling methods were compared. These three methods, vacuuming the filter surface, swabbing the filter surface, and eluting filter dust in a buffer, were selected as representative of previously published methods. Our findings suggest that vacuum and swab samples produced more repeatable and representative bacterial communities than did elution. Furthermore, given the reduced labor and cost of vacuum and swab methods, and the additional advantage that these two methods may also be applied to sampling dust from other home surfaces, vacuum and swab sampling of HVAC filter dust are found to be superior to elution.