Full Text (PDF)
Abstract
Background: Ambient air pollution, particularly nitrogen dioxide (NO₂), has been associated with adverse birth outcomes, though evidence on its relationship with low birth weight (LBW) remains mixed. This spatial ecological study examined the association between neighborhood-level NO₂ concentrations, socioeconomic deprivation, and LBW prevalence in Toronto, Canada.
Methods: We analyzed aggregate birth data from 2009 to 2011 across 140 Toronto neighborhoods (n = 90,871 births). LBW rates were linked with modeled ambient NO₂ and PM₂.₅ concentrations from the Canadian Urban Environmental Health Research Consortium. Socioeconomic indicators, including material deprivation and ethnic concentration, were derived from the Ontario marginalization index. Bayesian Poisson regression with conditional autoregressive priors was used to account for spatial autocorrelation.
Results: The average LBW rate was 7.35%, exceeding the provincial average of 6.5%. Neighborhood NO₂ concentrations ranged from 12 to 52 ppb. No statistically significant associations were observed between NO₂, PM₂.₅, or ethnic concentration and LBW. However, a 1 ppb increase in NO₂ was associated with a relative risk (RR) of 1.002 (95% confidence interval [CI]: 0.996-1.008), and increased material deprivation was associated with a RR of 1.053 per standard deviation (95% CI: 0.977-1.125). Trends were consistent with findings from individual-level studies.
Conclusion: This study demonstrates the utility of Bayesian spatial modeling with neighborhood-level data for evaluating urban environmental health risks. While no significant associations were observed, modest trends suggest possible relationships between NO₂ exposure, socioeconomic deprivation, and LBW risk. To better assess causality, future research should incorporate individual-level data, improved spatial and temporal exposure alignment, and confounding control for maternal risk factors such as age, smoking, and comorbidities.
License
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Article Type: Original Article
J CONTEMP STUD EPIDEMIOL PUBLIC HEALTH, Volume 7, Issue 1, 2026, Article No: ep26017
https://doi.org/10.29333/jconseph/18117
Publication date: 13 Mar 2026
Article Views: 5
Article Downloads: 4
Open Access References How to cite this article