We conducted a randomized trial of portable HEPA air cleaners with pre‐filters designed to also reduce NH₃ in non‐smoking homes of children age 6‐12 with asthma in Yakima Valley (Washington, USA). Participants were recruited through the Yakima Valley Farm Workers Clinic asthma education program. All participants received education on home triggers while intervention families additionally received two HEPA cleaners (child's sleeping area, main living area). Fourteen‐day integrated samples of PM_2.5 and NH₃ were measured at baseline and one‐year follow‐up. We fit ANCOVA models to compare follow‐up concentrations in HEPA vs control homes, adjusting for baseline concentrations. Seventy‐one households (36 HEPA, 35 control) completed the study. Most were single‐family homes, with electric heat and stove, A/C, dogs/cats, and mean (SD) 5.3 (1.8) occupants. In the sleeping area, baseline geometric mean (GSD) PM_2.5 was 10.7 (2.3) μg/m³ (HEPA) vs 11.2 (1.9) μg/m³ (control); in the living area, it was 12.5 (2.3) μg/m³ (HEPA) vs 13.6 (1.9) μg/m³ (control). Baseline sleeping area NH₃ was 62.4 (1.6) μg/m³ (HEPA) vs 65.2 (1.8) μg/m³ (control). At follow‐up, HEPA families had 60% (95% CI, 41%‐72%; p < .0001) and 42% (19%‐58%; p = .002) lower sleeping and living area PM_2.5, respectively, consistent with prior studies. NH₃ reductions were not observed.

中文翻译：

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便携式 HEPA 空气净化器在减少哮喘儿童农业队列中室内 PM2.5 和 NH3 的有效性：一项随机干预试验

我们在 Yakima Valley（美国华盛顿）的 6-12 岁哮喘儿童的非吸烟家庭中对带有预过滤器的便携式 HEPA 空气净化器进行了一项随机试验，该试验旨在降低 NH _{3 的}含量。参与者是通过亚基马谷农场工人诊所哮喘教育计划招募的。所有参与者都接受了家庭触发教育，而干预家庭额外接受了两个 HEPA 清洁器（儿童睡眠区、主要生活区）。PM _2.5和 NH _{3 的}14 天综合样本在基线和一年随访时测量。我们拟合 ANCOVA 模型来比较 HEPA 与对照家庭的后续浓度，调整基线浓度。71 个家庭（36 个 HEPA，35 个控制）完成了研究。大多数是单户住宅，配备电暖气和炉子、空调、狗/猫，平均 (SD) 5.3 (1.8) 名居住者。在睡眠区，基线几何平均值 (GSD) PM _2.5为 10.7 (2.3) μg/m ³ (HEPA) vs 11.2 (1.9) μg/m ³（对照）；在生活区，它是 12.5 (2.3) μg/m ³ (HEPA) 与 13.6 (1.9) μg/m ³（对照）。基线睡眠面积 NH ₃为 62.4 (1.6) μg/m ³ (HEPA) vs 65.2 (1.8) μg/m ³（控制）。随访时，HEPA 家庭的 睡眠和居住面积 PM _2.5分别降低了 60%（95% CI，41%-72%；p  < .0001）和 42%（19%-58%；p = .002），与先前的研究一致。未观察到NH ₃减少。