Early-life exposure to PM2.5 and risk of acute asthma clinical encounters among children in Massachusetts: a case-crossover analysis

• Authors: Roxana Khalili, University of California Irvine; Scott Bartell, Emory University; Xuefei Hu, Emory University; Yang Liu, Emory University; Howard Chang, Emory University; Candice Belanoff, Boston University; Matthew Strickland, Emory University; Veronica M. Vieira, University of California Irvine
• Journal Title: Environmental Health and Preventive Medicine
• Volume: Volume 17, Number 1
• Publisher: BMC (part of Springer Nature) | 2018-02-21, Pages 20-20
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.1186/s12940-018-0361-6
• Subjects: Health Sciences, Public Health
• Keywords: Science & Technology; Life Sciences & Biomedicine; Environmental Sciences; Public, Environmental & Occupational Health; Environmental Sciences & Ecology; Asthma; Child; Particulate matter; Low birthweight; Case-crossover; AIR-POLLUTION EXPOSURE; AEROSOL OPTICAL DEPTH; CHILDHOOD ASTHMA; HOSPITAL ENCOUNTERS; ULTRAFINE PARTICLES; RESPIRATORY HEALTH; RSV BRONCHIOLITIS; FINE PARTICLES; BIRTH COHORT; CITY

Abstract

Background: Associations between ambient particulate matter < 2.5 μm (PM2.5) and asthma morbidity have been suggested in previous epidemiologic studies but results are inconsistent for areas with lower PM2.5 levels. We estimated the associations between early-life short-term PM2.5 exposure and the risk of asthma or wheeze clinical encounters among Massachusetts children in the innovative Pregnancy to Early Life Longitudinal (PELL) cohort data linkage system. Methods: We used a semi-bidirectional case-crossover study design with short-term exposure lags for asthma exacerbation using data from the PELL system. Cases included children up to 9 years of age who had a hospitalization, observational stay, or emergency department visit for asthma or wheeze between January 2001 and September 2009 (n = 33,387). Daily PM2.5 concentrations were estimated at a 4-km resolution using satellite remote sensing, land use, and meteorological data. We applied conditional logistic regression models to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CI). We also stratified by potential effect modifiers. Results: The median PM2.5 concentration among participants was 7.8 μg/m3 with an interquartile range of 5.9 μg/m3. Overall, associations between PM2.5 exposure and asthma clinical encounters among children at lags 0, 1 and 2 were close to the null value of OR = 1.0. Evidence of effect modification was observed by birthweight for lags 0, 1 and 2 (p < 0.05), and season of clinical encounter for lags 0 and 1 (p < 0.05). Children with low birthweight (LBW) (< 2500 g) had increased odds of having an asthma clinical encounter due to higher PM2.5 exposure for lag 1 (OR: 1.08 per interquartile range (IQR) increase in PM2.5; 95% CI: 1.01, 1.15). Conclusion: Asthma or wheeze exacerbations among LBW children were associated with short-term increases in PM2.5 concentrations at low levels in Massachusetts.