Air Cleaners Do Not Thwart Most Effects of Secondhand Smoke

From Medscape Medical News

Emma Hitt, PhD

August 4, 2011 — Air cleaners significantly reduce particulate matter (PM) levels but are not enough to reduce exposure to secondhand smoke in inner-city children with asthma residing with a smoker, a new study has found.
Arlene M. Butz, ScD, MSN, CPNP, with the Division of General Pediatrics at The Johns Hopkins University School of Medicine, in Baltimore, Maryland, and colleagues reported the findings in the August issue of the Archives of Pediatrics & Adolescent Medicine.
"Despite parental awareness that second-hand smoke exacerbates asthma, 40% to 67% of inner-city children with asthma reside in a household with at least 1 smoker," the study authors note.
According to the researchers, PM concentrations of secondhand smoke exposures have previously been found to be reduced with the use of air cleaners.
The current study sought to test the ability of an air cleaner only (n = 41), an air cleaner plus a health coach (n = 41), or delayed air cleaners (control; n = 44) in reducing PM, air nicotine, and urine cotinine concentrations. The number of symptom-free days was also evaluated.
Eligible children were aged 6 to 12 years, with clinician-diagnosed asthma, symptom frequency, and/or controller medication use signifying persistent asthma. A smoker, who smoked more than 5 cigarettes per day and resided in the home at least 4 days per week, was also present.
Reductions in mean fine and coarse PM (PM_2.5 and PM_2.5-10) concentrations from baseline to 6 months were significantly higher in both air cleaner groups vs the control group (PM_2.5 concentrations, P = .003; and PM_2.5-10 concentrations, P = .02 for differences between both air cleaner groups and control).

However, the presence of secondhand smoke, as measured by air nicotine and urine cotinine concentrations, was comparable among the groups.
Use of a health coach did not further reduce PM concentrations.
Air cleaner groups, when combined, had a significant increase in symptom-free days during the past 2 weeks (1.36 vs 0.24 symptom-free days for control group children from baseline to follow-up), representing an increase of 14% to 18% symptom-free days, and yielding an additional 33 symptom-free days per year.
"Use of air cleaners in homes of children with asthma was associated with a significant reduction in indoor PM concentrations and increase in symptom-free days," the study authors note. "However, the reduced indoor PM levels were not sufficiently decreased to meet EPA [Environmental Protection Agency] standards for outdoor air quality," they add.


Arch Pediatr Adolesc Med. 2011;165:741-748.