May is National Stroke Awareness Month and it’s a great time to take stock of one of the risks that may not immediately come to mind when we think of stroke. The risk factor we are referring to is air pollution, an important reason to be concerned about current efforts to roll back air quality standards.
Pollution can come from a variety of sources, traffic, factories, power generation, wildfires or even heating the home or cooking on a wood stove. The greatest single indoor source of pollution is smoking – a danger to the smoker and to anyone who is nearby.
A recent study, which used data from the United States and China, is the first to investigate the interaction between air quality and the number of stroke cases. The U.S. and China are the two largest emitters of greenhouse gases and are responsible for about one-third of global warming to date, according to Longjian Liu, M.D., Ph.D., lead study author and associate professor of epidemiology and biostatistics at Drexel University in Philadelphia.
Liu’s team evaluated air quality data collected between 2010 and 2013 from 1,118 counties in 49 states in America and from 120 cities in 32 provinces in China. Particulate matter (PM) is the term for particles found in the air, including dust, dirt, smoke and liquid droplets. Particles less than 2.5 micrometers in diameter (PM2.5) pose the greatest health risks due to their small size (1/30th diameter of a human hair and not visible to the human eye). They are created from combustion from cars, power plants, forest fires and other sources.
Across the two countries, researchers found that the total number of stroke cases rose 1.19 percent for each 10 micrograms per cubic meter of air (µg/m3) an increase of PM2.5.
When compared to other regions of the U.S., the South had the highest average annual PM2.5 and also the highest prevalence of stroke. Acute short-term effects of air pollution tend to strike people who are elderly or already struggling with heart disease, and can increase the risk of stroke, heart attack, arrhythmias and heart failure. But the risk of death is greater from long-term exposure. Current science suggests air pollution adds to the development and progression of atherosclerosis and may also play a role in high blood pressure, heart failure and diabetes.
The study also found seasonal changes in temperature affected the incidence of stroke – with rates of stroke increasing in hot weather. It also found that women and the elderly appear more vulnerable to stroke risk due to air quality and heat-related diseases.
If you have heart disease or a respiratory illness, talk to your doctor about risks in your area and take heed of air quality alerts. Stay indoors and take whatever precautions you can to reduce your exposure to air-borne pollutants.
Stroke Awareness Message “When it comes to stroke, prevention is the key! But, please learn to recognize the signs and symptoms of stroke and ACT FAST. Signs and symptoms include facial drooping, slurred speech, sudden vision changes, and weakness on one side of the body. Stroke is a medical emergency and you are encouraged to call 911,” Wendy Barrilleaux, PT, DPT, NCS, Director of Stoke Services, St. Dominic Comprehensive Stroke Center.