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Prenatal Particulate Air Pollution and Asthma Onset in Urban Children. Identifying Sensitive Windows and Sex
Hsiao-Hsien Leon Hsu1, Yueh-Hsiu Mathilda Chiu2, Brent A Coull3,4
11 Department of Preventive Medicine.
Insights
Prenatal exposure to fine particulate matter (PM2.5) during mid-pregnancy is linked to childhood asthma, particularly in boys. Identifying sensitive exposure windows is key to understanding respiratory health impacts.
Area of Science:
- Environmental Health
- Pediatric Respiratory Medicine
- Epidemiology
Background:
- Particulate air pollution exposure during fetal development can impact lung growth.
- The timing of exposure during gestation may influence the risk of postnatal respiratory disorders.
Purpose of the Study:
- To identify critical windows of prenatal exposure to fine particulate matter (PM2.5) linked to asthma development in children.
- To investigate the association between PM2.5 exposure during pregnancy and childhood asthma using an innovative methodological approach.
Main Methods:
- Utilized a cohort of 736 children, estimating daily PM2.5 exposure via a satellite-based model.
- Employed distributed lag models to assess the relationship between weekly PM2.5 averages and asthma diagnosis by age six.
- Examined potential effect modification by child's sex.
Main Results:
- Increased PM2.5 exposure between 16-25 weeks of gestation was significantly associated with asthma development by age six.
- A significant interaction between PM2.5 exposure and sex was observed (P=0.01).
- The association between prenatal PM2.5 exposure and asthma was primarily observed in boys.
Conclusions:
- Higher prenatal PM2.5 exposure during midgestation is associated with asthma development by age six in boys.
- Characterizing vulnerable developmental windows can offer insights into the mechanisms of air pollution's impact on respiratory health.
Rationale:
The influence of particulate air pollution on respiratory health starts in utero. Fetal lung growth and structural development occurs in stages; thus, effects on postnatal respiratory disorders may differ based on timing of exposure.
Objectives:
We implemented an innovative method to identify sensitive windows for effects of prenatal exposure to particulate matter with a diameter less than or equal to 2.5 μm (PM2.5) on children's asthma development in an urban pregnancy cohort.
Methods:
Analyses included 736 full-term (≥37 wk) children. Each mother's daily PM2.5 exposure was estimated over gestation using a validated satellite-based spatiotemporal resolved model. Using distributed lag models, we examined associations between weekly averaged PM2.5 levels over pregnancy and physician-diagnosed asthma in children by age 6 years. Effect modification by sex was also examined.
Measurements And Main Results:
Most mothers were ethnic minorities (54% Hispanic, 30% black), had 12 or fewer years of education (66%), and did not smoke in pregnancy (80%). In the sample as a whole, distributed lag models adjusting for child age, sex, and maternal factors (education, race and ethnicity, smoking, stress, atopy, prepregnancy obesity) showed that increased PM2.5 exposure levels at 16-25 weeks gestation were significantly associated with early childhood asthma development. An interaction between PM2.5 and sex was significant (P = 0.01) with sex-stratified analyses showing that the association exists only for boys.
Conclusions:
Higher prenatal PM2.5 exposure at midgestation was associated with asthma development by age 6 years in boys. Methods to better characterize vulnerable windows may provide insight into underlying mechanisms.
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