Efficiency of a Low-Energy Wetted-Surface Multi-Annulus Denuder Sampler for Viable and Nonviable Aerosol Collection

Capture efficiency of a wetted-surface low-energy sampler (LES) was evaluated for polystyrene latex (PSL) microsphere aerosol and a Bacillus subtilis aerosol. The observed absolute capture efficiency for PSL microspheres was higher than predicted by theory for the particle sizes used (0.7, 1.6, and 3.0 mm), suggesting hygroscopic particle growth via water uptake by residual detergent coatings. Bioaerosol capture efficiency was evaluated relative to the AGI-30 impinger using mature B. subtilis. The bioaerosol was quasi-monodisperse with MMAD approximately 1 mm and GSD 1.2–1.3. Observed efficiencies for B. subtilis were substantially better for the LES than the AGI-30 at the lowest sampling flow rate used (5 L/min), but relatively poor at higher flow rates. Factors potentially influencing sampling efficiency were improved viability maintenance and adequate hygroscopic bioorganism growth in the LES. These results demonstrate that low-energy bioaerosol sampling using a wetted-surface multi-annulus denuder may be more sensitive than AGI-30 impinger sampling for some organisms