Indoor and Outdoor Residential Ammonia Concentrations in a Low-Income Cohort of Children with Asthma in an Area of Intensive Agricultural Production

摘要

Ambient PM and NH3 have been associated with measures of asthma health among children in rural Yakima Valley, Washington. Unlike PM, ammonia (NH3) has received little attention as a residential air contaminant of concern for children with asthma. We are conducting a randomized trial of a community-based asthma education program combined with home high efficiency air cleaners in 65 Yakima children (age 6-12 years) with poorly controlled asthma from nonsmoking homes located <800 m of dairy and/or crop operations. The HEPA air cleaner includes a pre-filter designed to reduce NH3. Two-week integrated NH3 samples using Ogawa passive samplers are collected at baseline and follow-up from the child's sleeping area and home yard. Here we report the baseline (pre-randomization) NH3 results. Geometric mean (GSD) NH3 was 11.8 ug/m3 (2.7 ug/m3) in the outdoor samples (n=65; max 97.6 ug/m3) and 67.5 ug/m3 (1.8 ug/m3) in the bedroom samples (n=63), with 10 of these exceeding the batch-specific upper limit of quantitation. Indoor and outdoor concentrations were weakly but not statistically significantly correlated (Pearson rho=0.13, p=0.33). Indoor levels were statistically significantly (p<0.05) associated with the winter season but no other variables tested in bivariate and multivariable regression models. In a subset of children with data on NH3 product use in the home, use of glass cleaner was statistically significantly associated with indoor NH3 concentrations. Future work will explore the effectiveness of the HEPA cleaners at lowering indoor NH3 levels in the study households.