Air Pollution Increases Risk of Heart Disease and Stroke, Researcher Finds

Air pollution has been previously thought to only have links to an irregular heartbeat and nonfatal heart attacks

Breathing in air pollutants emitted by fossil fuels and wood burning incidents such as wildfires causes an increased risk of serious health effects like heart disease and stroke, studies suggest.

Researchers have known for years that air pollution is damaging to humans, causing up to 100,000 deaths here in the United States, NBC News reported. Air pollution has well-known links to respiratory issues such as asthma and difficulty breathing, and other heart issues such as an irregular heartbeat and nonfatal heart attacks, according to the Environmental Protection Agency. But the new study found that humans who are exposed to the two pollutants are more susceptible to developing cardiovascular illnesses, which doctors have thought to be mainly caused by high blood pressure, high cholesterol and obesity, according to the Centers for Disease Control.

The most recent study, done in Beijing, China, analyzed the past air pollution exposure of 8,867 patients at Fuwai Hospital who were suspected of having coronary heart disease. The patients, ages 25 to 92 years old, were among the entire Chinese population who were exposed to levels of particulate matter and nitrogen dioxide 95% above the rate considered safe by the Chinese government.

In China, government regulations allow for 35 micrograms of particulate matter in the air and for 40 micrograms of nitrogen dioxide. The study said that exposure to 30 micrograms of particulate matter caused a 27.2% increase in the risk for cardiovascular issues and that 20 micrograms of nitrogen dioxide caused a 24.5% increased risk.

“In the study conducted in China, we found that long-term exposure to outdoor air pollution and traffic pollutants, specifically PM2.5 (particulate matter) and NO2 (nitrogen dioxide), was associated with coronary artery calcium, a strong predictor of total coronary heart disease,” said Meng Wang, an assistant professor in the department of epidemiology and environmental health at the University at Buffalo and lead author of the study.

Particulate matter and nitrogen dioxide are both substances in the air that come from natural and human-made causes. While the main source for the gases is from the use of fossil fuels, they can be released into the atmosphere by other methods. Common activities often not associated with environmental issues like wood burning is known to release particulate matter into the air, said Beth Gardiner, the author of the book “Choked: Life and Breath in the Age of Air Pollution.”

Exposure to pollutant levels higher then the national standard is not uncommon in China, where the average concentration of particulate matter is 80 micrograms and 42 micrograms of nitrogen dioxide, Wang said. In Beijing, as part of the country's Air Pollution Action Plan, particulate matter levels have dropped on average by 35% since 2013, from 85 micrograms to 58 micrograms. This was largely achieved by halting the use of coal for power and heat, according to ChinaDialogue.

In a similar study on ozone levels in the U.S. published last month, Wang said he found that Americans are also facing increased health risks as a result of air pollution. Testing 6,619 adults between the ages 45 to 84 in six cities across the country, the researchers found that long-term exposure to ozone causes an increased risk of stroke.

“Therefore, they (the studies) reflect that different air pollutants may have different effects on different beds of human artery, both of which are closely related to cardiovascular health in people,” Wang said.

Ozone, a gas produced from both natural and human-made sources, is helpful in the Earth’s upper-atmosphere where it reduces the amount of harmful UV radiation exposure to humans, according to the CDC. When ozone enters the lower-atmosphere, it is known to have adverse health effects on humans. The gases' link to respiratory problems such as asthma have been well-documented and is acknowledged by the EPA.

Although Wang's two studies do not draw any conclusions on the health effects of particulate matter in the U.S., it has been found by other researchers to have an effect. A study in 2016 said that a reduction of both particulate matter and ozone in the U.S. could save thousands of lives, NBC News reported.

And, air pollution trends in the U.S. have been getting worse since then. In both 2017 and 2018, the number of days with unhealthy air has increased by 15% compared to the number of unhealthy days between 2013 and 2016, NBC News reported.

Yet compared to the rest of the world, the U.S. has historically been considered somewhat of an environmental success story because of the passage of the Clean Air Act and creation of the EPA in 1970, Gardiner said.

“America has really been a story of sort of slow, steady progress, which was achieved through science based regulations and effective enforcement,” Gardiner said.

Not only do countries like India and China have exponentially higher levels of air pollution than the U.S., but much of Europe has higher pollutant levels as well, Gardiner said. The continent’s countries have not been enforcing the climate regulations they set on fossil fuel emissions, allowing pollutants to enter the air at higher and more damaging levels.

Besides air pollution's main source, fossil fuels, which comes from transportation methods such as cars and planes, power-plants run by both coal and natural gas, and industrial agriculture, Gardiner said wood burning and wildfires produces a lot of particulate matter.

A California wildfire in 2017 emitted the same amount of particulate matter in a week that the state's motorists emit in a year, NBC News reported.

“Even though it smells really nice and appealing, it is actually very bad for your health because it is those tiny chemicals that can penetrate and go all the way into your body,” Gardiner said.

Though Wang’s studies have only evaluated the cardiovascular risks, the same air pollutants he examined have also been found to increase the risk of neurological disorders such as Parkinson’s Disease, dementia and premature birth, Gardiner said.

Researchers at the Stockholm Environment Institute found in 2010 that particulate matter contributed to 18%, or about 2.7 million, of the 14.9 million total preterm births globally. The highest rate for a country was China, where more than 40% of preterm births were correlated with particulate matter.

The rate of preterm births is relatively low in the U.S., but is still impacted by air pollution, with 5 to 10% of preterm births correlated to air pollution exposure. According to the CDC, 1 in 10 births are finished prematurely overall and 17% of infant deaths are from preterm births.

"Air pollution (i.e. particulate matter and ozone) is still associated with human mortality in the U.S. even when the concentration is below the current U.S. standard for particulate matter and ozone," Wang said.

In fact, there is no safe amount of air pollution, noted Wang. There will be some level of impact on humans no matter the amount of ozone and particulate matter present.

"The research says that there is no safe level. And that sounds scary, but there is a more positive way to phrase it too. Which is the more that you can reduce pollution, the more people’s lives you can save and the more illnesses you will prevent," Gardiner said.

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