PURPOSE: Outdoor particulate matter (PM) exposure contributes to childhood asthma morbidity. Although pre-school age children are estimated to spend over 90% of time indoors, little is known about the effect of indoor PM exposure on asthmatic children. We investigated the effect of indoor PM exposure on the health of pre-school age asthmatic children.
METHODS: Children with asthma ages 2-6 years from the Baltimore Indoor Environmental Study of Asthma in Kids (BIESAK) were enrolled. Indoor air from the children's homes was sampled for 3-day time periods at baseline, 3, and 6 months. Caregivers completed a health outcomes questionnaire. Indoor PM2.5 and PM10 levels were related to asthma symptoms and rescue medication use during the previous 2 weeks and asthma-related health care utilization using negative binomial and logistic regression models. Generalized estimating equations were used to account for repeated outcome measures in the longitudinal data analysis.
RESULTS: Of the 150 children studied, 91% were African-American and 87% had public health insurance. Children spent an average of 21 hours/day indoors. Longitudinal analyses showed that each 10 μg/m3 increase in indoor PM10 was associated with a 3% increase in the incidence of respiratory symptoms (cough, wheeze, or chest tightness) (p= 0.06), nocturnal symptoms (p=0.06), and exercise-related symptoms (p=0.03). For every 10 μg/m3 increase in indoor PM10, there was a 6% increase in incidence of wheeze severe enough to limit speech (p<0.01) and a 5% increase in beta-agonist use (p=0.09). Similar relationships were found between health outcomes and PM2.5 levels, but in several cases, these did not reach statistical significance. Indoor PM level was not associated with acute health care use for asthma (ED visits or hospitalizations).
CONCLUSION: In this cohort of asthmatic pre-school age children living in inner-city Baltimore, increased indoor PM exposure was associated with greater symptoms, rescue medication use, and functional limitation, though not with acute health care use.
CLINICAL IMPLICATIONS: Reduction of indoor PM levels in the homes of pre-school asthmatic children should be targeted to improve respiratory health.
DISCLOSURE: Meredith McCormack, None.