"Here's how to create your own personal Stage 2 Smog Alert: Buy an [ionic] indoor air purifier."

Thus begins the MSNBC.com article which reports that air ionizers can generate ozone levels in a room that exceed the worst smog days in Los Angeles, according to a new study.

Ionic air purifiers are extremely popular, but they emit ozone as a by-product and create potentially unhealthy conditions. Ozone is a powerful lung irritant, and it's especially dangerous to children, the elderly, and asthma sufferers.

High in the atmosphere, ozone protects us from harmful radiation, but down here on the earth's surface, ozone can exacerbate asthma, damage the lungs, and cause shortness of breath and throat irritation.

A University of California research team found that some ionic air purifiers produce ozone levels that would trigger a Stage 2 Smog Alert outdoors. The last Stage 2 Smog Alert was in Southern California in 1988, and citizens were advised to stay indoors.

"These machines are insidious, "said Barbara Riordan, chairperson of the California Air Resources Board (ARB). "Marketed as a strong defense against indoor air pollution, they emit ozone, the same chemical that the ARB and U.S. Environmental Protection Agency have been trying to eliminate from our air for decades. More chilling is that some people susceptible to the ill effects of ozone will eagerly bring these Trojan horses home."

Don't buy an air purifier just because it's cheap and looks cool, or else there's a good chance you'll wind up polluting your air and jeopardizing the health of your lungs.

Get the facts on ozone and air purifiers in this Air Purifier Buying Guide.