A potential link between stroke prevalence and air quality has been reported at the 2016 International Stroke Conference in Los Angeles.
Researchers from the Drexel-SARI Low Carbon and Healthy City Study analyzed data from 1118 counties in 49 US states as well as 120 cities in 32 Chinese provinces. US data, taken from the years 2010 to 2013, had particulate matter (PM) measures of 2.5. Chinese data, taken between 2012 and 2013, had measures of Air Pollution Index (API).
Few previous studies have used multilevel regression techniques to investigate the association between climate change and air pollution with stroke risk. Therefore, researchers hypothesized that the disproportionately distributed stroke rates across cities and counties within a country are significantly associated with air pollution and temperature.
In the US, the highest PM 2.5 level was in July (10.2 μg/m3) and the lowest level in October (7.63 μg/m3) for the aforementioned time period. Stroke prevalence significantly increased by 1.19% for every 10 μg/m3 increase of PM 2.5 (P<.001), according to multilevel regression analysis. There was considerable variability across states and counties—more than 70% of the stroke variation rate existed in counties (P=.017) while 18.7% existed in states (P=.047).
Meanwhile, in China, December represented the highest API month with 75.76 in 2012 and 97.51 in 2013. July represented the lowest API with 51.21 in 2012 and 54.23 in 2013. In cities with higher API concentrations, stroke prevalence was significantly higher. Air quality and stroke risk were significantly mediated by temperatures.
“The study, using nationally representative data, is one of the first studies to address a positive and complex association between air quality and prevalence of stroke, and a potential interaction effect of temperatures on the air and stroke association,” researchers concluded.
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Liu L, Liu H, Yang X, Jia F, Wang M. Abstract 36. Mapping and multilevel modeling of climate change and air pollution with risk of stroke in the United States and China: findings from the Drexel-SARI low carbon and healthy city study. Presented at the 2016 International Stroke Conference; February 17-19, 2016; Los Angeles, CA.