Environmental Health (Apr 2019)

A tensor product quasi-Poisson model for estimating health effects of multiple ambient pollutants on mortality

  • Li-Jun Xu,
  • Shuang-Quan Shen,
  • Li Li,
  • Ting-Ting Chen,
  • Zhi-Ying Zhan,
  • Chun-Quan Ou

DOI
https://doi.org/10.1186/s12940-019-0473-7
Journal volume & issue
Vol. 18, no. 1
pp. 1 – 10

Abstract

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Abstract Background People are exposed to mixtures of highly correlated gaseous, liquid and solid pollutants. However, in previous studies, the assessment of air pollution effects was mainly based on single-pollutant models or was simultaneously included as multiple pollutants in a model. It is essential to develop appropriate methods to accurately estimate the health effects of multiple pollutants in the presence of a high correlation between pollutants. Methods The flexible tensor product smooths of multiple pollutants was applied for the first time in a quasi-Poisson model to estimate the health effects of SO2, NO2 and PM10 on daily all-cause deaths during 2005–2012 in Guangzhou, China. The results were compared with those from three other conventional models, including the single-pollutant model and the three-pollutant model with and without first-order interactions. Results The tensor product model revealed a complex interaction among three pollutants and significant combined effects of PM10, NO2 and SO2, which revealed a 2.53% (95%CI: 1.03–4.01%) increase in mortality associated with an interquartile-range (IQR) increase in the concentrations of all three pollutants. The combined effect estimated by the single-pollutant model was 5.63% (95% CI: 3.96–7.34%). Although the conventional three-pollutant models produced combined effect estimates (2.20, 95%CI, 1.18–3.23%; 2.78, 95%CI: 1.35–4.23%) similar to those of the tensor product model, they distorted the estimates and inflated the variances of the estimates when attributing the combined health effects to individual pollutants. Conclusions The single-pollutant model or conventional multi-pollutant model may yield misleading results in the presence of collinearity. The tensor product quasi-Poisson regression provides a novel approach to the assessment of the health impacts of multiple pollutants by flexibly fitting the interaction effects and avoiding the collinearity problem.

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