Effectiveness of portable HEPA air cleaners on reducing indoor endotoxin, PM10, and coarse particulate matter in an agricultural cohort of children with asthma: A randomized intervention trial

We conducted a randomized trial of portable HEPA air cleaners in the homes of children age 6-12 years with asthma in the Yakima Valley, Washington. All families received asthma education while intervention families also received two HEPA cleaners (child's bedroom, living room). We collected 14-day integrated samples of endotoxin in settled dust and PM10 and PM10-2.5 in the air of the children's bedrooms at baseline and one-year follow-up, and used linear regression to compare follow-up levels, adjusting for baseline. Seventy-one families (36 HEPA, 35 control) completed the study. Baseline geometric mean (GSD) endotoxin loadings were 1565 (6.3) EU/m(2) and 2110 (4.9) EU/m(2), respectively, in HEPA vs. control homes while PM10 and PM10-2.5 were 22.5 (1.9) mu g/m(3) and 9.5 (2.9) mu g/m(3), respectively, in HEPA homes, and 19.8 (1.8) mu g/m(3) and 7.7 (2.0) mu g/m(3), respectively, in control homes. At follow-up, HEPA families had 46% lower (95% CI, 31%-57%) PM10 on average than control families, consistent with prior studies. In the best-fit heterogeneous slopes model, HEPA families had 49% (95% CI, 6%-110%) and 89% lower (95% CI, 28%-177%) PM10-2.5 at follow-up, respectively, at 50th and 75th percentile baseline concentrations. Endotoxin loadings did not differ significantly at follow-up (4% lower, HEPA homes; 95% CI, -87% to 50%).

Automated summary

The study found that using HEPA air cleaners in the homes of children with asthma can significantly reduce the concentration of PM10 air pollutants. Additionally, HEPA families showed a significant decrease in PM10-2.5 concentrations at different baseline levels, but there was no significant change in endotoxin loadings at follow-up.