Combating Indoor Air Pollution
with Air Filters
Indoor air pollution is an ongoing problem in America today. Listed below are the major causes and how air filters can help you fight against indoor air pollution. Remember truly effective portable air filters are rarely sold in discount or hardware stores.
In the past two decades, we have sealed our homes for energy efficiency without providing appropriate air exchange equipment. We have also filled our home with a variety of toxic products including particle board furniture and cabinets; chemical cleaning products; pesticides; plastics; synthetic fibers in furnishings and construction, carpeting, and drapes; scented products; gas appliances and heaters; and commonly used products made from petro chemicals. As a result of these actions, the level of toxic pollution inside our homes is not only increasing, it is often higher than that of air outside -- sometimes higher than the maximum allowable outdoor standards.
To best reduce indoor air pollution, pollutants should be eliminated at their source, and ventilation should be increased. In some circumstances, air filters can be useful in controlling levels of indoor air pollution:
The Types of Cleaning Methods
To remove pollutants, air-cleaning devices use one or more of four types of cleaning methods. Each method works differently, and each removes different pollutants.
Activated carbon works by absorption, i.e., pollutant gases are attracted by and stick to the carbon. Among the several types of activated carbon are available, coconut shell carbon is considered to be the highest quality. Carbon should be at least one-inch thick.
Mechanical filters work by trapping particles. High-Efficiency Particulate Arrestance (HEPA) filters are rated at 99.9% efficient for particles 0.3 microns in size (dust, pollen and plant & mold spores).
Electrostatic filters attract particles by static electricity. There are two kinds: electronic air cleaners (electrostatic precipitators), which are not recommended because they are inefficient and produce ozone positive ions, and electronically charged plastic panel filters (electret) that can be inserted into the central heating system. These are very efficient at removing dust particles and chemicals that cling to the dust.
Negative ion generators and ionizers are quite limited as air cleaners. These are very effective at removing the particles found in cigarette smoke and smog, cleaning air so that it becomes clear and odorless. They cannot, however, remove invisible odorless toxic gases that are also present in smoke and smog, and they are practically useless for ridding the air of dust or pollen. Do not confuse products that produce ozone to clean the air with ion or ionizers. Ozone is very dangerous to your health and is not effective in cleaning the air.
The Purchasing of an Air Filter
Air filters can be purchased as portable models, or they can be built into oneís central heating/air-conditioning system. The cleaning capabilities of a portable unit are only limited to the air in the room in which it is being used. They are most effective if no outside air is entering from adjacent rooms, open windows, or a central air system. Air filter decisions should be based on individual needs and preferences. To evaluate an air filter, answer the following questions:
1What specific pollutants do you want to remove from the air, and how effective is a specific system at removing them? There are two classes of air pollutants: gases or misty vapors of volatile chemicals (e.g., formaldehyde, plastics, paints, solvents, and pesticides) and perfumes and particulate (e.g., bits of pollen, dust, mold and animal dander). If your house contains chemical emitters, you will probably need to remove vapors. If you are sneezing or experiencing other allergic symptoms, you will probably need to remove particles from the air.
2From what areas do you want to remove pollutants? Each unit is designed to remove pollutants from the air contained in a certain measured space. The amount of filter media the unit contains, the rate at which the air flows through the media, the size of the motor, and all other aspects of the unitís design are geared to the designated room size. Several filters may be needed to clean continuously the air throughout a house, or a portable unit moved from room to room may be sufficient.
3What is the cost of the filter? Generally, prices correspond to room sizes and the amount of filter media used. Prices range from $200-$1,000.
4How will the filter look, and how much noise will it make? Most filters are nondescript painted metal boxes or cylinders. Metal housings are preferable. A variable speed filter will allow for noise level adjustments as well as air flow.
5What do you have to do to maintain the filter? Activated carbon and other filter materials must be changed regularly, depending on frequency of use. Activated carbon typically last about 2,000 hours (12 hrs. per day for six months). Prefilters must be changed more frequently. HEPA filters last for several years.
The American Environmental Health Foundation (AEHF) was founded more than 25 years ago as nonprofit organization to provide education and research into the field of environmental medicine and chemical sensitivity. Besides researching causes and effects of environmental illness, AEHF also researches products. To help you, the consumer and to provide additional funding for research and education, AEHF opened a retail store 18 years ago that sells only high quality environmentally safe products for the home, school and office. (The AEHF store has an inventory of more than 1,500 items.) All of the products we offer in our store, catalog and internet store have been tested and approved by our staff and an outside group of environmental physicians and experts. We can assist you in evaluating your indoor air. We offer a number of air tests kits and several excellent air filters.
8345 Walnut Hill Lane, Suite 225, Dallas, TX 75231
214/361-9515 or 800/428-2343
or visit our Internet site & store, www.aehf.com