Even a Single Day of Air Pollution Increases Stroke Risk

When environmental health advocates speak about the dangers of dirty air, the effects are often categorized as long term and cumulative. But the more scientists delve into the subtleties of the human body and what outside influences can do it, the more they realize that even short term exposures can be harmful. That's been especially true lately when looking at pregnant moms and the exposure to fetuses in certain stages of development. Not it turns out to true when looking at the other end of the age spectrum.

A new examination of 103 studies involving 6.2 million stroke hospitalizations and deaths in 28 countries published online at the BMJ (British Medical Journal) found that almost every type of industrial air pollution contributed to a higher risk of stroke. And the higher level of exposure to the pollutant, the higher the risk of stroke.

Increases in the levels of Nitrogen Dioxide, Sulfur Dioxide, Carbon Monoxide and fine Particulate Matter were all associated with increases in strikes and hospitalizations. Not surprisingly, the strongest correlations were on the day of actual exposure, but the effects of PM, otherwise known as soot, were longer lasting. Missing from the list is ozone, or plain old smog, which studies have shown increases asthma and heart attacks on its own.

According to the report, strokes account for five million deaths worldwide every year and cause en even greater number of disabilities.

The lead author, Dr. Anoop Shah, from the University of Edinburgh, said that there was little an individual can do when there's a bad air day going on but stay indoors

“If you’re elderly, or have co-morbid conditions, you should stay inside,” he said. But policies leading to cleaner air would have the greatest impact, he said. “It’s a question of getting cities and countries to change.”