Less Than Fresh Air

Some air cleaners could make your air unhealthy.

Recent study: Some ionizing air filters expose users to high levels of ozone. Experts agree that exposure to ozone in excess of 80 parts per billion for eight hours or longer can cause coughing, wheezing and chest pain, and deaden the sense of smell. In a recent test, five ionizing room air cleaners performed poorly, and some emitted potentially harmful levels ozone—Brookstone Pure-Ion V2, Sharper Image Professional Series Ionic Breeze Quadra S1737 SNX, Ionic Pro CL-369, Ioniz Air P4620 and Surround Air XJ-2000.

The best air cleaner still available from the test is the Friedrich C-90A, which effectively cleans ak and emits little ozone.