AIRWEIGHS: A randomized controlled trial of air cleaners in normal weight and overweight/obese children with asthma.

Background: Overweight and obesity is a risk factor for increased asthma morbidity among children, and overweight/obese children with asthma may be more susceptible to air pollution.

Objective: To test the hypothesis that there would be greater improvement in asthma from an air cleaner intervention to reduce indoor air pollution among overweight/obese children compared to normal weight children.

Methods: AIRWEIGHS is a randomized, placebo-controlled air cleaner trial designed to reduce indoor air pollution and test the differential health impact among overweight/obese children versus normal weight children with asthma. Asthma outcomes and home air pollution were measured at baseline and 12 weeks post-intervention. The primary outcome was maximum symptom days over 2 weeks, defined as the largest value of: days of slowed activity; number of nights of waking; days of coughing, wheezing, chest tightness due to asthma. Secondary outcomes included asthma questionnaires, lung function, fractional exhaled nitric oxide, and exacerbations.

Results: 164 children (10.9+2.5 years, 41% female, 85% Black, 59% overweight/obese) were randomized to portable air cleaners with high-efficiency particulate air (HEPA) filters or identical devices without filters. Average baseline air pollutants (UFP 45.3 μm/m, PM 24.0 μg/m, PM 33.0 μg/m, NO 16.7 ppb) did not differ by study group. There were greater reductions in the intervention group versus placebo group (UFP 64.0%, PM 64.4%, PM 54.7%, NO 11.7%; p<0.05 each). There was no improvement in primary or secondary outcomes, with no difference between normal weight and overweight/obese children.

Conclusion: Air cleaners effectively reduced indoor air pollution but there was no observable benefit in asthma outcomes in children.