26 Apr

Let’s Clear the Air: Air Filtration Systems for Your Home

Last month we talked about your HVAC system undergoing a spring cleaning for peak performance and effectiveness for the warmer months. Of course, warmer weather means opening windows to allow fresh air in OR keeping windows closed to maintain a cooler temperature. Either way, we seemed doomed to contribute to the amount of air pollution in our homes. Warmer weather brings allergy season, so we want to keep allergens—like pollen—out. But keeping a home sealed up means all the indoor pollution—like dust, mold, dander, etc.—is trapped inside. Ugh!
Animal dander, dust mites, mold, pollen, lingering cigarette smoke—it’s all right there in the air, not to mention your bath towels, bedding, and furniture. Improving your indoor air quality should start with identifying what pollutant sources you want to minimalize inside your home, and finding which system will effectively help you and your family breathe easier.
According to Consumer Reports, in the average home the air is replaced by outside air every 2 hours (newer homes are tighter so may take longer for the air to circulate). Therefore, minimizing sources of indoor pollutants can make a difference in indoor air quality. A typical first effort by most people is to purchase an inexpensive portable space purifiers to ease asthma or allergy symptoms, or perhaps to have someone come in for a thorough duct cleaning. While these may help the issue temporarily, they are not a complete solution. You can increase the control over the quality of air you breathe inside your home with an air filtration system.
While it would seem obvious to want ‘clean air’ inside our homes, you first have to ask yourself what are the triggers to respiratory distress in those who live inside the home. Do you want to dust less? Sneeze less often? Relieve asthma symptoms? Reduce odors? Eliminate mold and fungus spores? Remove airborne bacteria that can cause serious illnesses? Destroy airborne viruses? Any of these alone are reasons you may want an air purifier. However, each one may require a different solution or type of system.


According to a recent article in This Old House Magazine, “Today’s tighter houses keep the weather outside, but they also keep contaminants inside. According to the Environmental Protection Agency, the air indoors where we spend as much as 90 percent of our time can be more polluted than even city smog. And dirt you can see is just the beginning. That dust collecting on end tables and bookshelves is only a fraction of what’s actually swimming around in the air: an invisible mix of dust mites, pollen, dander, mold, and smoke that can be annoying to breathe and hazardous to your health.”
The first line of defense against airborne contaminants is always to keep a house clean and well ventilated. But for some people sensitive to various irritants, that may not be enough. In addition, increasingly, indoor air quality ranks among one of the most important green building modifications homes are making. This is where air filtration systems become relevant. Household air filters are available in two basic types: media filters, which create a physical barrier that traps minute particles, and electronic filters, which use a high-voltage charge to attract and capture contaminants. A few air filters are hybrids that combine both methods, and some include activated carbon elements to combat odor.
Typically, air filters are either built into the heating and cooling system (whole-house filters) or are freestanding units that can be placed in individual rooms (portable filters with self-contained fans). With some simple research, you can discover which features and which type of systems are most important to consider for your home.

Whole-House Filters

The most efficient way to filter household air is through your home’s forced-air heating or central air-conditioning system. The filters are built into the return-air ductwork, trapping particles as air passes through. Such systems are passive; as long as the fan is running, they are constantly filtering all the air in your house.

Portable Room Air Filters

Most portables employ highly effective HEPA filters, which are not generally used in whole-house systems because they need more-powerful fans than furnaces can provide. Some portable units, called ion air cleaners, use electrostatic precipitator technology. Ion units, which don’t require fans, are typically quieter than HEPA models and cost less to operate because there are no filters to replace. But these units may produce trace amounts of the lung irritant ozone as a by-product of the ionization process
Portables powered by fans are rated by “clean-air delivery rate” (CADR), which measures both air movement and gunk-trapping effectiveness. It’s important to buy a filter that’s big enough. Manufacturers recommend that the CADR be at least two-thirds the room’s area in square feet — so a 15-by-20-foot room (300 square feet) would need a filter with a CADR rating of 200. (The calculation assumes 8-foot ceilings.)


Whether or not you have an air filtration system, try these simple steps to reduce indoor air irritants:
• Vacuum often and thoroughly with a vacuum with HEPA filtration. It’s a simple way to help control airborne particulates like dust. Be sure to choose a top-rated one that cleans while minimizing emissions back into the air.
• Ban smoking indoors.
• Maintain your heating and cooling equipment and change air filters regularly. If pollen or related allergies keep you from opening windows, run your air conditioner or forced-air cooling system with a clean air filter.
• Minimize use of candles and wood fires.
• Use exhaust fans in kitchen, bath, and laundry areas.
• Don’t store chemicals, solvents, glues, or pesticides near your living quarters. Few air filter systems are effective at removing volatile organic compounds (VOCs) and other gaseous pollutants from a home.
• Control Moisture in typically damp areas of the home: use an air conditioner (with a clean filter) or a dehumidifier to help keep things dry in the basement and other damp spaces, where mites and mold tend to thrive.
• Air It Out: open windows when weather permits and turn on exhaust fans at other times to remove indoor pollutants.
Like with any system that involves air circulation, Keep it Clean: Any type of air purifier won’t work well if the filter is clogged and dusty, and, if filter is full, it may stop working entirely.
Whole-home air-cleaning systems are increasingly popular and can be incorporated into almost any HVAC system—whether a new build or a retrofit—and are available in various sizes, types and price ranges.
Air filtration systems can do a good job of clearing the air inside your home. While medical research is inclusive if they will actually make you feel better, if you find a system that addresses and controls the specific respiratory issues within your household, that is what makes a system worthwhile. It makes you and your family breathe easier.


In our next blog, we will look at two systems we recommend for those interested in an air filtration system.

1 Clearing the Air: Whole-house and portable filters trap dust, pollen, and more
By Max Alexander of This Old House Magazine

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