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PART I GENERAL DESCRIPTION ON AIR CLEANING
A wide variety of molds also can produce mycotoxins at various times during their lifecycles. Building occupants can experience
potentially serious health problems if they are exposed to high levels of these compounds, but this is rare in most indoor
environments.
Although becoming a lesser issue in public buildings, ETS is still found in many homes, hotels, casinos, and in some
restaurants and bars. Environmental tobacco smoke alone contains more than 4,700 airborne substances, including gases
and particles from incompletely burned tobacco, of which 243 are known carcinogens.
Regardless of whether an indoor environment is the product of new construction or renovation, providing good indoor air quality
starts during the design and construction phases and continues throughout a building's life, and, it is never too late to start
managing IAQ in older buildings. Indoor environmental experts recommend three primary strategies for good IAQ, especially
when integrated into a building's overall operation and maintenance. The following highlights each of these strategies: source
control, ventilation and air cleaning.
Source control
The US Environmental Protection Agency (USEPA), the American Lung Association (ALA) and other experts agree that source
control is the only completely effective way to remove pollutants from indoor environments. They also agree that total
eradication of indoor air contaminants often is not feasible or practical. A more realistic goal is to use building materials,
furnishings, finishes, office equipment, and cleaning products and processes that emit low levels of VOCs. Surface cleaning
also removes larger particles and kills bacteria and viruses on floors, furniture, walls, doorknobs, bedding and linens, and
bathroom fixtures. In addition, keeping the heating, ventilating and air-conditioning (HVAC) system in good working order and
air ducts and drip pans clean is important for minimizing dust and particle accumulation and indoor mold growth within the
system.
Source control also involves inspecting a building regularly inside and out for any signs of water damage, which is a good
indicator that moisture levels are high enough to support indoor mold growth. The best way to prevent indoor mold growth is to
eliminate all sources of excess moisture, from leaks in the building envelope, improper building pressurization, an inefficient or
malfunctioning HVAC system, appliances to building occupant activities.
Ventilation
Ventilation and air cleaning are invaluable for picking up where controlling sources of indoor air pollutants leaves off. The two
work hand-in-hand, as many types of air purifiers are an integral part of the HVAC system.
A well-designed and properly operating HVAC system brings in and conditions outdoor air and circulates the air through the
building. The primary benefit beyond warming, cooling and managing the humidity the air is to dilute indoor air pollutants to
minimize their impact on the indoor environment and building occupants. The HVAC system also transports indoor air
contaminants outside. In addition, the HVAC system is invaluable for maintaining appropriate building pressurization, which is
critical for preventing moisture intrusion. The downside is the HVAC system may bring in outdoor air pollutants as well as pick
up indoor pollutants, such as mold spores, allergens, dust and VOCs from one area of the building and transport them to
another.
Air cleaning
Simply stated, with respect to air cleaning the goal is to remove indoor pollutants by trapping them inside a mechanical device.
Experts emphasize that air-cleaning devices alone cannot ensure good IAQ, particularly where ventilation itself is inadequate.
As noted, air cleaning is most effective when used in conjunction with source control and ventilation (USEPA 2006). Air
cleaners / purifiers employ various types of filtration technologies, which can be used in portable units that can be moved from
room to room and can be attached to HVAC systems.
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