The PureAir(tm) air purification system from Lennox Industries, Inc. (Richardson, TX) reduces the absolute toxicity of the treated airstream through the removal of particles, bioaerosols, and odors/chemicals, according to the manufacturer. Air passes through a 4-in. MERV 9 pleated filter, UVA lamps, and a metal mesh filter. This process is designed to capture and destroy 75% of particles and 60% of bioaerosols as small as 3 microns.