Here in Silicon Valley, we're all looking for clean, healthy buildings. Both Owners and employees want clean, fresh-smelling surroundings  Air in buildings is typically moved through the spaces using large electric fan units known as "air handlers". In most buildings, the air handlers draw a percentage of fresh air from the outside, mix it with ambient air from within the building, and then use the heating and air conditioning system or cool it, as well as dehumidify it or add humidity depending on the location and time of year.
The more pure, clean air that comes, the more bacterial infectious air goes out.