Efficiency of portable HEPA air purifiers against traffic related combustion particles

Exposure to diesel combustion particles is known to cause and exacerbate respiratory conditions, including asthma. High efficiency particulate air (HEPA) purifiers can provide health benefits by reducing concentrations of these particles. National standards call for air purifiers to be tested using tobacco smoke, as well as aerosolized dust, pollen, and potassium chloride (KCl) particles. Little is known about the efficiency of HEPA air purifiers against diesel particles. Previous studies performed with respirator filters have shown higher penetration of combustion generated particles compared to standard test particles. Within a controlled laboratory setting, we compared the Clean Air Delivery Rate (CADR) of six models of air purifiers with diesel and KCl particles, and measured noise during operation. CADR was determined for total concentration and size-selectively for particles of 0.03–1 μm. Lowest CADRs were consistently found for particles