Effect of ambient O on mortality due to circulatory and respiratory diseases in a high latitude city of northeast China.

In recent years, O pollution had been worsening in China and became a major challenge for human health. To evaluate the O effects on circulatory and respiratory mortality in Harbin, a high latitude city of northeast China, we applied a time-series study from 2014 to 2016. After collecting data and adjusting for the effects of confounders, we built the generalized additive model to assess the associations between O and mortality at different lag days. The results showed that an interquartile-range (IQR) increase in O concentration corresponded to excess risk (ER) of 2.00% (95%CI: - 0.25-4.30%) for circulatory mortality at lag 0 and 8.02% (95%CI: 4.18-12.01%) for respiratory mortality at lag 2 days in the single-pollutant model. Stratified analysis showed that O had a greater effect on females than on males. The effect of O exposure on circulatory mortality was stronger during the warm period, while the opposite trend was founded for respiratory mortality. The sensitivity analysis showed that the effects of O were relatively independent and the major results were robust.