A Johns Hopkins Children’s Center study shows that air cleaners can significantly reduce household air pollution and lower rates of asthma symptoms among kids living in homes with smokers.

The improvements are similar to those achieved by using anti-inflammatory asthma drugs.

However, the level of air nicotine remained, leaving kids at risk of some effects of secondhand smoke.

So, the study researchers concluded in the Aug. 1 issue of the Archives of Pediatrics & Adolescent Medicine that air cleaners should only be used as a temporary measure as smokers seeks to quit.

“Air cleaners appear to be an excellent partial solution to improving air quality in homes of children living with a smoker but should not be viewed as a substitute for a smoke-free environment,” lead investigator Arlene Butz, an asthma specialist at the Children’s Center and professor of pediatrics at the Hopkins University School of Medicine, said in a statement.

The researchers followed 115 children for six months. Asthma is the most common chronic illness among children, with some 6.5 million affected in the United States, according to the Centers for Disease Control and Prevention.

About a third of U.S. kids live with a smoker.