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Author Notes:

Roxana Khalili, Email: roxanak@uci.edu

RK performed the analyses and drafted the initial manuscript with contribution from all authors.

VMV, SMB, HC, CB, and MJS provided technical input to the analysis and manuscript preparation.

XH and YL developed the exposure model.

VMV conceived the study and its design.

All authors have read and approved the final manuscript.

Health data was provided by the Massachusetts Department of Public Health and should not be considered an endorsement of this study or its conclusions.

The health data obtained from the PELL data system are not publicly available due to patient confidentiality reasons but may be requested from the Massachusetts Department of Public Health.

This study was approved by the Institutional Review Board (IRB) (Reference number: UCI IRB HS# 2012–8784).

The authors declare that they have no competing interests.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.


Research Funding:

This work was supported by grant number R01ES019897 from the National Institute of Environmental Health Sciences (NIEHS). Its contents are solely the responsibility of the authors and do not necessarily represent the views of NIH. YL and XH were partially supported by NASA Applied Sciences Program (grant no. NNX11AI53G).


  • Science & Technology
  • Life Sciences & Biomedicine
  • Environmental Sciences
  • Public, Environmental & Occupational Health
  • Environmental Sciences & Ecology
  • Asthma
  • Child
  • Particulate matter
  • Low birthweight
  • Case-crossover
  • CITY

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


Journal Title:

Environmental Health and Preventive Medicine


Volume 17, Number 1


, Pages 20-20

Type of Work:

Article | Final Publisher PDF


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.

Copyright information:

© 2018 The Author(s).

This is an Open Access work distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).
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