The dangers of dirty air are obvious whether you are a miner working with coal or in the same room as a smoker. There is also fibers, viruses, bacteria, molds and much more so a means besides filtration is needed. Air purification is still a relatively new field with room for improvement and integration at many steps.

Sinan Company-Non-toxic paints, glues, cleaners etc. Last I checked this California co was for sale at $37.000

Solar Air-Germicidal air disinfection with ultraviolet light.

Trojan Technologies Inc. announced it has been awarded a contract for approximately $600,000 to supply ultraviolet (UV) systems to four wastewater plants in the state of Espirito Santo, Brazil.

UV Treatment-A study led by McGill University of Montreal suggests that mounting UVGI lamps in air ducts can improve the health of a building's occupants. While it's been known for some time that zapping cooling coils and drip pans with UV rays can cut down microbial action, this study is considered to be the first significant demonstration of the technique's health benefits.

Workplace Air-Keeping it clean from Twin Plant, Mexico's industrial magazine.

Xenon Corp-Using pulsed light they have learned much on how to destroy anthrax and other things in just one second.