Abstract Number: 625 Working Group: Bioaerosols: Characterization and Environmental Impact
Abstract Although use of automobile air conditioning (AC) was shown to reduce in-vehicle particle levels, its microbial aerosol exposure risk is not adequately characterized. Here, both AC and engine filter dust samples were collected from 30 automobiles in four different geographical locations in China. Biological contents (bacteria, fungi and endotoxin) were studied using culturing, high throughput gene sequence as well as Limulus amebocyte lysate (LAL) methods. In-vehicle viable bioaerosol concentrations were directly monitored using an ultraviolet aerodynamic particle sizer (UVAPS) before and after use of AC for 5, 10 and 15 mins.
Regardless of locations, the vehicle AC filter dusts were shown to be laden with high levels of bacteria (up to 26150 CFU/mg), fungi (up to 1287 CFU/mg) and endotoxin (up to 5527 EU/mg). More than 1000 bacterial species including human pathogens were detected in the filter dusts. In addition, pathogenic fungal species were also found abundant. Here, we observed unexpected fluorescent peaks around 2.5 μm during the first 5 minutes use of AC, which can be attributed to the re-aerosolization of those filter-borne microbial agents. This work presented evidence that use of automobile AC, if not cleaned or disinfected properly, would predispose the in- vehicle people to respiratory infections.