Effectiveness of air purifier on health outcomes and indoor particles in homes of children with allergic diseases in Fresno,California: A pilot study

Objective: Epidemiologic studies indicate that indoor air pollution is correlated with morbidity caused by allergic diseases. We evaluated the effectiveness of reducing the levels of indoor fine particulate matter <2.5 micrometer diameter (PM_2.5) in Fresno, California using air purifiers on health outcomes in children with asthma and/or allergic rhinitis. Methods: The active group (with air purifiers) and the control group consisted of eight houses each. Air purifiers were installed in the living rooms and bedrooms of the subjects in the active group during the entire 12-week study duration. Childhood asthma control test, peak flow rate monitoring, and nasal symptom scores were evaluated at weeks 0, 6, and 12. Results: At 12 weeks, the active group showed a trend toward an improvement of childhood asthma control test scores and mean evening peak flow rates, whereas the control group showed deterioration in the same measures. Total and daytime nasal symptoms scores significantly reduced in the active group (p = 0.001 and p = 0.011, respectively). The average indoor PM_2.5 concentrations reduced by 43% (7.42 to 4.28 μg/m³) in the active group (p = 0.001). Conclusions: Intervention with air purifiers reduces indoor PM_2.5 levels with significant improvements in nasal symptoms in children with allergic rhinitis in Fresno.