Air pollution and respiratory infections during early childhood: an analysis of 10 European birth cohorts within the ESCAPE Project

Background: Few studies have investigated traffic-related air pollution as a risk factor for
respiratory
infections during early childhood.
Objectives: We aimed to investigate the association between air pollution and pneumonia, croup,
and otitis media in 10 European birth cohorts—BAMSE (Sweden), GASPII (Italy), GINIplus
and LISAplus (Germany), MAAS (United Kingdom), PIAMA (the Netherlands), and four INMA
cohorts (Spain)—and to derive combined effect estimates using meta-analysis.
Methods: Parent report of physician-diagnosed pneumonia, otitis media, and croup during early
childhood were assessed in relation to annual average pollutant levels [nitrogen dioxide (NO2), nitrogen
oxide (NOx), particulate matter ≤ 2.5 μm (PM2.5), PM2.5 absorbance, PM10, PM2.5–10 (coarse
PM)], which were estimated using land use regression models and assigned to children based on their
residential address at birth. Identical protocols were used to develop regression models for each study
area as part of the ESCAPE project. Logistic regression was used to calculate adjusted effect estimates
for each study, and random-effects meta-analysis was used to calculate combined estimates.
Results: For pneumonia, combined adjusted odds ratios (ORs) were elevated and statistically significant
for all pollutants except PM2.5 (e.g., OR = 1.30; 95% CI: 1.02, 1.65 per 10-μg/m3 increase
in NO2 and OR = 1.76; 95% CI: 1.00, 3.09 per 10-μg/m3 PM10). For otitis media and croup,
results were generally null across all analyses except for NO2 and otitis media (OR = 1.09; 95% CI:
1.02, 1.16 per 10-μg/m3).
Conclusion: Our meta-analysis of 10 European birth cohorts within the ESCAPE project found
consistent evidence for an association between air pollution and pneumonia in early childhood, and
some evidence for an association with otitis media.