In a new study, researchers found that long-term exposure to fine particulate outdoor air pollution is a major contributor to heart disease and death.
But even small reductions in air pollution levels can result in a reduction of disease risk.
The research was conducted by a team at Oregon State University.
The massive study used data from the long-running Prospective Urban Rural Epidemiology (PURE) study.
For the current paper, researchers analyzed 157,436 adults between 35 and 70 years old in 21 countries from 2003-2018.
Overall, the study found a 5% increase in all cardiovascular events for every 10 microgram-per-cubic-meter increase in the concentration of air pollutant particles under 2.5 microns in size (PM2.5).
Factoring in the vast range of concentrations in PM2.5 recorded across the globe, which means 14% of all cardiovascular events documented in the study can be attributed to PM2.5 exposure.
The risks in low- and middle-income countries were mostly the same as the risks found in high-income countries.
The PURE study chose multiple countries from low, middle, and high-income brackets to address a gap in existing research, as most air pollution studies have centered on people in high-income countries with relatively low concentrations of air pollution.
The current study looked at PM2.5 particles because they are small enough to be breathed deep into the lungs where they can cause chronic inflammation.
These particles come from a range of combustion sources, including car engines, fireplaces, and coal-fired power plants.
Researchers worked with a set of cardiovascular disease risk factors, including individual variables like smoking status, eating habits and pre-existing cardiovascular disease; and household factors like household wealth and use of dirty fuels for indoor cooking.
Previous research in the PURE study found links between solid fuel use and kerosene use and cardiovascular disease.
They also referenced geographical variables, including whether a person’s location was rural or urban and general access to quality health care within each country.
In the data’s 15-year period, in which participants were followed for roughly nine years each, 9,152 people had cardiovascular disease events, including 4,083 heart attacks and 4,139 strokes. There were 3,219 deaths attributed to cardiovascular disease.
The strongest association between air pollution exposure and health outcomes was for strokes.
The team says a growing body of research finds that the risk of stroke is strongly impacted by exposure to PM2.5, especially at high concentrations.
Over the study’s time frame, some countries’ pollution levels improved, while some got worse.
One author of the study is Perry Hystad, an environmental epidemiologist in OSU’s College of Public Health and Human Sciences.
The study is published in The Lancet Planetary Health.
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