Air pollution is a major cause of several diseases and even premature death. Now, a study has found that even short-term exposure to air pollution may increase the risk of stroke.

A new study, published in the journal Neurology, found that people who had been exposed to higher concentrations of various types of gaseous and particulate air pollutants had a higher risk of suffering ischemic strokes. Here, researchers define short-term exposure as occurring within five days prior to the stroke.

Researchers found that higher concentrations of nitrogen dioxide showed a notable 28% increase in stroke risk, while high ozone levels indicated a 5% increase. Carbon monoxide was linked to a 26% increase, and sulfur dioxide, 15%.

Furthermore, heightened concentrations of PM1 (particles with a diameter less than 1 micron or μm) was linked to a 9% higher risk or strokes, whereas PM2.5 (fine particles from sources like vehicle exhaust and industrial emissions) showed a 15% increase, and PM10 (which includes larger particles like road dust and construction debris) displayed a 14% rise in stroke risk.

These higher levels of air pollution also correlated with a heightened risk of stroke-related deaths. Nitrogen dioxide led to a 33% increased risk of stroke-related death, while sulfur dioxide showed a substantial 60% increase. Additionally, PM2.5 was linked to a 9% higher risk, and PM10 showed a 2% increase in the risk of stroke-related mortality.

The meta-analysis involved a review of 110 studies, including more than 18 million cases of strokes, with the researchers examining pollutants like nitrogen dioxide, ozone, carbon monoxide, and sulfur dioxide. These findings highlighted the urgency of addressing the immediate consequences of environmental factors on public health.

"Previous research has established a connection between long-term exposure to air pollution and an increased risk of stroke. However, the correlation between short-term exposure to air pollution and stroke had been less clear," said Ahmad Toubasi, author of the study, as reported by News Medical.

"For our study, instead of looking at weeks or months of exposure, we looked at just five days and found a link between short-term exposure to air pollution and an increased risk of stroke," she added. "There is a strong and significant association between air pollution and the occurrence of stroke as well as death from stroke within five days of exposure."

The authors of the study suggested that increasing global efforts to create policies that reduce air pollution may help reduce the number of strokes and their consequences.

According to the World Health Organization, each year, approximately 15 million people worldwide suffer a stroke, which results in five million deaths annually.