All Air Filters Are Not Created Equal
Many families have one or more people who suffer from allergies or asthma, often due to poor air quality. But what many people do not realize is that they can do something about it.
The most effective and usually the least costly methods to limit indoor pollutants are source control and ventilation. Air cleaners may reduce the levels of certain pollutants, but air cleaning alone cannot adequately remove all the pollutants in a typical indoor air environment.
Since particles float in the air, they are difficult to live with and control. For example, pollutants can float around as a result of air movement from a person walking from one room to the next, the furnace or air conditioner blowing air, and the natural convection of warm air rising and cold air sinking. These every-day occurrences cause particles to swirl about. Some of the particles float in the air, while others settle on surfaces.
This natural settling may be so rapid that many air cleaners don’t solve the problem of indoor pollutants.
To make sure your air cleaner is doing what it is supposed to be doing, you need to look at two things. You will want to know the efficiency of the device itself (the percentage of the pollutant removed as it goes through the device) and the amount of air handled by the device. This is known as the unit’s clean air delivery rate (CADR).
Filters are the most common particle removal method. The filters are rated based on the size of particles removed. Other methods include electrostatic and ion generators. Particles entering an electrostatic air cleaner receive an intense positive electrical charge and adhere to plates, which have to be removed and washed. Ion generators charge the particles in a room so they are attracted to each other or to surfaces in the house. Independent tests of ion generators have shown no reduction in dust concentration in the air. Ozone can be a by-product of electrostatic cleaners, particularly if the units become loaded with material, and of ion generators. Ozone is a lung irritant and should not be used in an occupied space.
Machines are available that purposely produce ozone as an indoor cleansing agent. These should not be used in occupied areas. Ozone, which is an oxidizing agent, is a potent lung irritant that can cause respiratory distress. Although residential ozone-generating machines are promoted as air cleaners, independent studies have shown that the machines do not effectively destroy microbes or mold, remove odor sources or reduce indoor pollutants sufficiently to provide any health benefits.
