Once a topic relegated to obscure scientific research journals, indoor air quality, or the lack thereof, is a subject that's finally getting some well-deserved attention. As consumers have begun to appreciate the atmospheric consequences of airtight homes built from and filled with chemicals and other synthetic materials, they've been paying more attention to reports that say indoor air often contains unhealthy levels of airborne pollutants.
With the EPA ranking indoor air pollution as one of the top five environmental risks to public health, and the National Academy of Sciences estimating that it costs the U.S. between $15 and $100 billion in annual health care expenses, the issue of air quality inside our homes is one whose time has come. Only one question remains: What can we do to breathe a little easier?
For many, the best answer lies in air cleaning systems, a fast fix for many indoor air problems. Unlike expensive retrofits or a wholesale banishment of the modern conveniences that create indoor air pollution, air filters and other similar devices provide a solution that's inexpensive, effective, and sacrifice-free.
Practice Your Own Clean Air Act
When shopping for an air cleaner, it's important to remember that not all technologies remove all pollutants. Different air purifiers use different methods, and each has its own limitations in terms of the kinds of air pollution it can handle. Further complicating the picture is the fact that many devices incorporate more than one technology.
To help you keep it all straight and find the device that's best for you, here's a look at the different technologies available, the types of air pollution they remove, and some air cleaning machines in which they are found:
- Activated Carbon Filters clean by trapping pollutants in microscopic pits present in the carbon and by a physical process called adsorption in which gases adhere themselves to a material's surface. Activated carbon is steam-treated to increase the number of cavities. It provides moderate filtration and odor removal and will remove many common gaseous pollutants and volatile organic compounds (VOCs-chemical compounds that exist in a gaseous form at room temperature), pesticides, combustion by-product gases, tobacco smoke particulates, odors, ozone and many organic chemicals. Used in UV Air Purifier, AAPS 10000 Series, AAPS 20000 Series, Healthmate, Healthmate Jr., Roomaid, Desktop Air Filter.
- Corona Discharge Devices are not filters, but they do destroy contaminants using a process called electronic plasma incineration. Essentially a miniature lightning factory, such devices destroy bacteria, viruses, molds, odors, dust, and tobacco-smoke particulates and gases. The process also creates purifying negative ions and small amounts of ozone. Used in Personal Air Supply, Deluxe Personal Air Supply, Sani-Mate.
- Electrostatic Filters use a plastic filter media that becomes negatively charged via static electricity that's built up on its surface by passing air currents. (Some electrostatic filters have a permanent charge.) This negatively charged surface attracts and holds those pollutants that are positively charged including molds, pollens, bacteria, and particulates like asbestos, animal dander, and tobacco smoke particles. Electrostatic filters are not very efficient on their own and are often used as a pre-filter in a more comprehensive system. Used in Desktop Air Filter.
- Electrostatic Precipitators generate negative electric charges and impart them to passing pollutants. Now negatively charged, these contaminants are attracted to a series of positively charged collection plates. Like electrostatic filters, precipitators will capture molds, pollens, bacteria and particulates like asbestos, animal dander and tobacco smoke particles.
- HEPA Filters were originally developed to remove radioactive particles from the air in nuclear labs. HEPA stands for "High Efficiency Particulate Air". These filters consist of a dense maze of fibers that trap at least 97% of all particles down to 0.3 microns in size. HEPA filters excel at removing particulates like asbestos, dust, pollen, mold, animal dander, and tobacco smoke particles. They will also remove bacteria and viruses. Used in UV Air Filter, Blueair, Healthmate, Healthmate Jr., Roomaid.
- Ion Generators work by releasing negatively charged ions into the air, but do not actually filter the air. Instead, these ions attract positively charged pollutants and transfer their charge to them. The newly negatively charged pollutants are drawn to a positively charged surface. Some ion generators include such a surface, others do not. If there is no positively charged surface, the particles, made heavier by the ions, simply fall to the floor where they should be regularly vacuumed. Ion generators generally remove only smaller particulate pollution types including tobacco and smog-related particulates, and bacteria. Evidence suggests that negative ions can also create a feeling of well-being, produce greater mental and physical energy, and bring relief from allergies and asthma. Used in UV Air Filter, Blueair, Car Ionizer.
- Ozone Generators work by creating ozone, a highly reactive form of oxygen that can destroy many contaminants. However, ozone is also an air pollutant itself, one that can harm skin, eyes, and mucous membranes, and affect respiration. Exposure to concentrations of ozone as low as 80 parts per billion can cause such effects, and the FDA has set a limit of 0.5 parts per billion for all indoor ozone devices. In spite of this regulation, their use in the home continues to spark debate about the potential risks and rewards of intentionally adding ozone to indoor air. Many ozone generators come with a timer, allowing you to program the unit to run only when the house is unoccupied. Ozone is very effective at destroying bacteria, viruses, and odors and is a great choice for moldy basements, garages, or other areas outside of your main living space. It will also break down certain VOCs into less harmful compounds. However, ozone is also capable of reacting with existing pollutants to create new types that weren't previously present. Used in Ozone Generator.
- Ultraviolet Light Purifiers use UV light to kill airborne disease germs, bacteria and viruses but do not filter the air. Though this technology effectively destroys pathogens, it is best used in conjunction with a type of air filter. Used in UV Air Filter.
- Zeolites are any of a group of natural aluminum silicate minerals that, like activated carbon, excel at removing odors and many gaseous pollutants via adsorption. Unlike carbon, however, zeolites can be easily recharged by outdoor exposure to sunlight which frees the adsorbed pollutants and restores the minerals for reuse. Used in Healthmate, Heathmate Jr., Air Refreshers.
Where to get the Air Purifiers described here
Go to http://www.gaiam.com
About the Author
Geoff Davis is a freelance writer and commercial inkslinger whose work has been featured in an variety of local and national media. He lives sustainably with his wife, daughter and faithful canine in the forested wilds of Monkton, Vermont.