Air Pollution May Increase Risk Of Some Types Of Strokes: Study

Exposure to air pollution may increase an individual’s risk of suffering certain types of strokes, according to the findings of new research. 

In a study published in the August issues of the American Heart Association’s journal Stroke, Chinese researchers found an association between particulate matter, which is a type of air pollution, and the risk of ischemic stroke.

Researchers studied patients from 26 Chinese cities, both northern and southern areas. They focused on hospital admissions for stroke, identified from electronic hospitalization summary reports from January 1, 2014, to December 31, 2015.

A total of 278,980 ischemic stroke hospital admissions were identified, as well as 69,399 hemorrhagic stroke hospital admissions.

Among southern China cities, an increase in particulate matter 2.5 (PM2.5) by 47 μg/m3 was linked to a 1% increased risk of hospitalization after suffering an ischemic stroke. Similarly, an increase in particulate matter 10 (PM10) by 76 μg/m3 was associated with an 0.8% increase in admissions for ischemic stroke.

Particulate matter is a type of  air pollution containing microscopic solid and liquid pollution particles. The number indicates the size of the particles. PM2.5 has particles 2.5 µm in size, while PM10 is larger with 10µm sized particles. When inhaled, this can cause serious respiratory and cardiovascular side effects.

A recent report released by the World Health Organization indicates 90% of the world’s population live in areas with high levels of air pollution.

Earlier this month, a study published in the New England Journal of Medicine indicated air pollution, even at levels deemed safe in the U.S., increase the risk of premature death.

Researchers said both PM2.5 and PM10 had strong effects on stroke admission risks. Study authors saws similar results in Northern China cities, where the pollution is more severe. An increase in PM2.5 was linked to a 1% increase in the risk of hospitalization from ischemic stroke. An increase in PM10 in Northern cities was linked to a 0.7% increase in ischemic stroke admissions.

The study concludes that there is no significant association between increased particulate matter concentrations and the likelihood of hemorrhagic stroke.

“This study suggests that short-term elevations in particulate matter may increase the risk of ischemic but not hemorrhagic stroke,” wrote study authors.

An ischemic stroke is when a blood vessel that leads to the brain is blocked by a clot. The clot may have formed in the vessel itself, or traveled from somewhere else in the body. More than 80% of strokes suffered by people worldwide are ischemic strokes. It is the most common type of stroke.

Hemorrhagic strokes are less common, but are responsible for about 40% of all stroke deaths. A hemorrhagic stroke is when a blood vessel in the brain bursts, or is weakened to the point where it breaks. This causes bleeding, swelling, pressure and damage to the brain in that area.

Another study published in 2016 indicated exposure to environmental pollution increases a person’s risk of heart disease and damage to the blood vessels. Damaged blood vessels may be more likely to experience blockages or stroke.