EFFECT OF HEATING-VENTILATION-AIR CONDITIONING SYSTEM SANITATION ON AIRBORNE FUNGAL POPULATIONS IN RESIDENTIAL ENVIRONMENTS

Commercial air duct sanitation services are advertised to the public a s being effective in reducing indoor aeroallergen levels despite the a bsence of published supporting data. Eight residential heat-ventilatio n-air conditioning (HVAC) systems in six homes and seven HVAC systems in five homes in winter and summer, respectively, were sampled to dete rmine fungal colony forming units (CFUs) prior to and after an HVAC sa nitation procedure was performed by a local company. Two houses in whi ch no sanitation procedure was performed served as controls in each st udy phase. Two sample sets were obtained at each HVAC system prior to cleaning in order to determine baseline CFU levels. The test HVAC syst ems. were then cleaned, and the HVAC systems allowed to operate as des ired by the residents. Posttreatment sampling was performed 48 hours a nd then weekly after cleaning for 8 weeks. The HVAC systems were analy zed by exposing sterile 2% malt extract media plates at a 90-degree an gle to the airflow at the air supply and air return vents. The baselin e CFUs were similar in the control and study houses. Eight weeks after sanitation, the study houses demonstrated an overall CFU reduction of 92% during winter and 84% during summer. No reduction in CFU values w as observed over the 8-week study period for the houses selected as co ntrols. Further, HVAC sanitation appeared to reduce the number of fung al colonies entering and leaving the HVAC system, suggesting that the HVAC contained a significant percentage of the total fungal load in th ese homes. These data suggest that HVAC sanitation may be an effective tool in reducing airborne fungal populations in residential environme nts.