|AllerAir 6000 AH|
In many possible emergency scenarios airborne particles, chemicals, smoke and odors will likely be a problem with a basic air exchange system providing little to no protection. While many sites online recommend HEPA filtration, this type of particle trapper is not designed for chemicals and odors. A great solution is a basic mechanical air purifier with a large, deep-bed activated carbon filter and HEPA filtration. Activated carbon was originally used in water and air filtration by the military (think gas masks, water filters etc.). It's able to attract and trap many times its weight in chemicals and odors. Paired with a HEPA (high efficiency particle filer), an air cleaner like this will cover the widest range of air pollutants.
A unit like the AllerAir 6000 Exec can also be used as a room air purifier or can be modified (AH model) to be used as a by-pass in your existing ventilation plan. The added benefit of an AllerAir unit is that it's designed first and foremost for function. Unlike an air purifier used by a typical home-owner (built as much for style as for filtration), AllerAir units are designed for industrial use. These are simple, robust units made for constant, 24/7 operation. There are no fancy digital panels to maintain or repair and almost no plastic parts to wear and crack. The filters and the 3-speed motor (max power-draw 156 Watts, but typical users leave it on the lowest setting) are housed in tough, powder-coated steel. The carbon filters can also be refilled rather than replaced (this survivalist thread discusses making your own activated carbon, but having some on hand in a sealed container is easier and more reliable.)
For more information on AllerAir air cleaners visit www.allerair.com. The room air cleaners (no by-pass modification) are also available on Costo.com.