Air Pollution Correlated With High Risk of in-Hospital Death From Stroke
A new study published in Neurology states high air pollution has an association with increased in-hospital death from stroke. Study researchers evaluated 3.1 million records of people hospitalized with any type of stroke in China and the air pollution exposure for the individual prior to hospitalization. Both average daily exposure in the year and week prior to hospitalization and different size of particulate matter in the air correlated with stroke outcomes.
With ever 10mcg/m3 increase in exposure to submicron particles (PM1), fine particulate matter (PM2.5), and respirable particulate matter (PM10), respectively, there was a 24%, 11%, and 9% increase in the risk of death from stroke when in the hospital. For the week prior to hospitalization, risk of death increased by 6%, 4%, and 3% with every 10 mcg/m3 increase in exposure to PM1, PM2.5, and PM10, respectively. Risk calculations were made after controlling for hypertension, diabetes, socioeconomic status, sex, and age. These risks were increased for people with ischemic vs hemorrhagic stroke. The mean age of people hospitalized with stroke was 67 and stroke mortality was 1%.
“Air pollution has been previously linked to a greater risk of stroke, and stroke is a leading cause of death worldwide,” said study author Hualiang Lin, PhD, of Sun Yat-sen University in Guangzhou, China. “What is lesser known is how the different sizes of particulate matter affect that risk. Our research found that the size of air pollution particles may affect a person’s risk of dying from stroke.”
Although risk of death when hospitalized was most strongly correlated with PM1 levels, based on the frequency of air particulate matter, researchers suggested reducing PM10 would have a larger impact on reducing stroke-related mortality. Modeling suggested a 10% and 21% mortality reduction from reduced weekly and yearly exposure to PM10.
“Our study includes measurements of PM1, which may be small enough to be inhaled deeply into lungs, pass through lung tissue, and circulate in the bloodstream,” said Lin. “Obtaining a deeper understanding of the risk factors of all particulate matter sizes and the magnitude of their possible effects may help reduce the number of deaths and improve the outcomes for people with stroke.”