Interactive Effect of Air Temperature and Fine Particulate Matter on the Hospital Admissions for Stroke in Shenzhen, China.

BACKGROUND

Stroke is a major health challenge in China. Numerous studies have linked stroke with temperature and fine particulate matter (PM), but findings varied by stroke subtypes and regions, and few explored the interactive effects of air temperature and PM. This study examines the association between air temperature, PM, and stroke hospital admissions in Shenzhen, a subtropical monsoon city in southern China.

METHODS AND RESULTS

We applied time-series generalized additive models to estimate the individual and interactive effects of air temperature and PM on stroke hospital admissions using daily records from 2015 to 2016. Subgroup analysis by sex, age, and education level was conducted, assessing admissions for hemorrhagic (n=8752) and ischemic (n=33 233) stroke separately. For hemorrhagic stroke, a 1 °C increase in temperature was significantly associated with a 2.3% (95% CI, -3.2% to -1.3%) decrease in hospital admissions, whereas higher levels of PM indicated an increased risk, though not significant. Conversely, for ischemic stroke, a 1 °C rise was significantly associated with a 1.0% (95% CI, 0.4%-1.6%) increase in admissions. The impact PM on stroke was more pronounced at higher concentrations, while showing no evident effects at lower levels. Interaction effects between temperature and PM were statistically significant for both stroke types, with stronger effects observed at 10 to 20 °C and PM concentration around 80 to 100 μg/m.

CONCLUSIONS

This study suggests lower air temperature may increase hemorrhagic stroke risk, whereas higher temperature and higher PM exposure may increase ischemic stroke risk. Interactive effects between temperature and PM were observed for both stroke types in Shenzhen.