Spending just five days in an area with air pollution can increase the risk of stroke and double the risk of dying from a stroke.
Researchers in Jordan reviewed more than 100 studies with data from 18 million stroke patients. They found that pollutants such as nitrogen dioxide, ozone, carbon monoxide and sulfur dioxide increased the risk of stroke by as much as 60 percent.
And experts estimate that up to a third of Americans live in areas where pollution is dangerously high.
These findings suggest that even short periods of time in highly polluted cities can have disastrous health consequences.
Dr. Ahmad Toubasi, lead author of the study and a doctor at the University of Jordan, said: ‘There is a strong and significant link between air pollution and the occurrence of stroke, as well as death from stroke within five days of exposure.
‘This highlights the importance of global efforts to create policies that reduce air pollution. This can reduce the number of strokes and their consequences.’
These pollutants can come from cars, power plants, forest fires and refineries.
Researchers in Jordan reviewed more than 100 studies on 18 million strokes. They found that pollutants such as nitrogen dioxide, ozone, carbon monoxide and sulfur dioxide increase the risk of dying from stroke by as much as 60 percent
Dr. Tubasi and his team looked at data from 110 observational studies conducted in Asia, Europe, North America and South America. The researchers also analyzed the presence of nitrogen dioxide, ozone, carbon monoxide and sulfur dioxide in the air within five days after people had an ischemic stroke, the most common type caused by a blood clot traveling to the brain.
They also measured exposure to particulate matter, or microscopic particles of dirt, dust and smoke. These range from less than one micron in diameter (PM1) to 10 times that size (PM10).
People exposed to higher concentrations of nitrogen dioxide were 28 percent more likely to have a stroke, while ozone was linked to a five percent increase. Carbon monoxide led to a 26 percent greater risk, while sulfur dioxide caused a 15 percent increase.
In addition, people exposed to higher concentrations of PM1 were nine percent more likely to have a stroke, with PM2.5 increasing the risk by 15 percent and PM10 increasing the risk by 14 percent.
The researchers also found that higher levels of short-term exposure to air pollution were associated with a greater risk of death from stroke. Exposure to nitrogen dioxide was linked to a 33 percent increased risk of death from stroke, and sulfur dioxide was linked to a 60 percent increase. Those exposed to higher levels of PM2.5 and PM10 were nine percent and two percent more likely to die from a stroke, respectively.
“Previous research has shown a link between long-term exposure to air pollution and an increased risk of stroke,” Dr Toubasi said.
‘However, the correlation between short-term exposure to air pollution and stroke was less clear. For our study, we did not look at weeks or months of exposure, but at just five days, and we found a link between short-term exposure to air pollution and an increased risk of stroke.’
Fine particles, or soot, are small particles in the air that are released from forest fires, wood stoves, coal-fired power plants, diesel engines and other sources.
This pollution consists of small microscopic particles in the air that can irritate the eyes, nose and throat.
In the short term it can cause itching, coughing, sneezing and shortness of breath.
Over time, these chemicals can build up in the lungs and bloodstream, disrupting body functions.
Furthermore, they can damage the DNA of the lungs and other vital organs and increase the risk of developing cancer.
Ozone pollutants, on the other hand, are also released by cars, power plants, refineries and power stations, but they have reacted with the sun’s ultraviolet radiation, creating ‘smog’.
Inhaling it is equivalent to ‘burning’ your lungs, doctors say.
These reactions create toxic gas that can cause damage to the lungs after just a few days of exposure and can be especially dangerous for people who suffer from asthma or COPD.
The American Lung Association’s State of the Air report also found that about 103 million people lived in the 124 counties that earned an F rating for ozone smog, and that 120 million Americans are in areas with “dangerously high” level of pollutants.
The researchers did note that one study limitation was that most of the data came from high-income countries, as there was limited data on lower-income areas.
The new study was published Wednesday in the journal Neurology.