Air purifiers

The efficiency of an air purifier depends on changing the filter regularly as recommended by the manufacturer.

Air purifiers for homes seem to be displayed and advertised more often in recent years.

Do they really work and do what the manufacturers say they will do — purify the indoor air? It will probably take some research and homework to select the right one.

So, should you use an air purifier? There are factors that need to be considered. The efficiency of a particular purifier, the size of the room in which it will be used, and other factors should be taken into account.

People with allergies, asthma and other respiratory conditions use them to help pull pollutants out of the air they breathe.

It could be difficult to know which one to choose with so many brands. Purifiers with HEPA, which stands for high efficiency particulate air filter, are often recommended.

The HEPA purifiers theoretically remove 99.97% of airborne particles, including bacteria, mold, dust and pollen from indoor air, according to the U.S. Environmental Protection Agency.

Of course, the efficiency depends on changing the filter regularly as recommended by the manufacturer. Air cleaners require periodic cleaning and filter replacement. Typically, manufacturers recommend changing the filters every 60 to 90 days.

The EPA does not recommend specific air cleaning devices but offers a guide on selecting one. See epa.gov/indoor-air-quality-iaq/air-cleaners-and-air-filters-home

Air purifiers have fans that draw in the air through a filter, which traps particles of a certain size. The smaller the particle it can trap, the better. The manufacturer's instruction should tell the size of particle it can trap. The filtered, clean air is then recirculated into the room.

Another source of information that should help in selecting the right air cleaner is the Association of Home Appliance Manufacturers. Check out aham.org.