Effectiveness of portable HEPA air cleaners on reducing indoor endotoxin, PM_(10), and coarse particulate matter in an agricultural cohort of children with asthma: A randomized intervention trial

摘要

We conducted a randomized trial of portable HEPA air cleaners in the homes of childrenage 6–12years with asthma in the Yakima Valley, Washington. All families receivedasthma education while intervention families also received two HEPA cleaners(child's bedroom, living room). We collected 14-dayintegrated samples of endotoxinin settled dust and PM_(10) and PM_(10-2.5)in the air of the children's bedrooms at baselineand one-yearfollow-up,and used linear regression to compare follow-uplevels, adjustingfor baseline. Seventy-onefamilies (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 PM_(10) and PM_(10-2.5)were22.5 (1.9) μg/m~3 and 9.5 (2.9) μg/m~3, respectively, in HEPA homes, and 19.8 (1.8) μg/m~3 and 7.7 (2.0) μg/m~3, respectively, in control homes. At follow-up,HEPA familieshad 46% lower (95% CI, 31%–57%)PM_(10) on average than control families, consistentwith prior studies. In the best-fitheterogeneous slopes model, HEPA families had 49%(95% CI, 6%–110%)and 89% lower (95% CI, 28%–177%)PM_(10-2.5)at follow-up,respectively,at 50th and 75th percentile baseline concentrations. Endotoxin loadings did notdiffer significantly at follow-up(4% lower, HEPA homes; 95% CI, −87% to 50%).