Air pollution should be one of the avoidable heart risk factors - just like smoking and excess fat - that doctors warn patients to steer clear of, according to a new statement from 20 heart experts.

Citing pollution’s heavy toll on cardiovascular health, the panel urges people to take steps to protect themselves from breathing heavy traffic fumes or industrial air pollution whenever possible, and public officials to pass laws to reduce air pollution.

“Cardiovascular disease is a huge global problem, causing immense suffering and premature death, as well as placing severe strain on national healthcare budgets and/or family finances,” said Dr. Robert Storey, a professor of cardiology at the University of Sheffield in the UK and senior author of the new position paper.

Air pollution causes more than 3 million deaths worldwide each year and causes 3.1 percent of all cases of disability, Storey and his coauthors write in the European Heart Journal.

Air pollution is also ninth most important on a list of modifiable heart-disease risk factors - ranking above low physical activity, high-salt diet, high cholesterol and drug use, the authors point out.

Although gaseous air pollutants can be dangerous too, Storey said, airborne particles are the biggest contributor to cardiovascular disease because they cause inflammation of the lungs and enter the circulation, inflaming blood vessels, provoking clots and causing heart rhythm disturbances.

Particulate matter includes coarse particles from road dust, construction work and industrial emissions and fine particles from traffic, power plants and industrial and residential burning of oil, coal or wood for heating.

The bulk of particulate air pollution is made up of these fine particles, known as PM2.5, that are less than 2.5 micrometers - about one fifth the size of visible dust.

The World Health Organization sets the safe outdoor exposure limit for PM2.5 at an average of 25 micrograms, or 25 millionths of a gram, per cubic meter of air over a 24-hour period, or average annual levels of 10 micrograms per cubic meter. In 2013, the U.S. Environmental Protection Agency lowered the 24-hour exposure limit to an average of 12 micrograms.

European studies have found that PM2.5 levels are often markedly higher near heavy traffic zones compared to elsewhere in the same city, and that the levels can more than double during rush hours, according to the position statement.

Some of the authors’ advice for people to protect themselves is as simple as walking, cycling and using public transportation instead of driving cars, and exercising in parks or gardens, rather than near busy roads.

And everyone should avoid being outside when pollution is highest, though this is especially important for infants, elderly and people with heart problems, the authors say.

People who live in heavily polluted areas should also consider ventilation systems with filtration in their homes, since a large portion of outdoor pollution can penetrate buildings.

The use of fossil fuels for heating and energy should also be decreased, according to the statement.

“Many countries have made good progress towards reducing risk factors such as smoking, high cholesterol and high blood pressure but much less effort has been extended on reducing exposure to air pollution,” Storey said in an email to Reuters Health.

Studies have shown even short-term exposure to high PM2.5 levels increases deaths from heart disease and respiratory disease, and that people living in places with high PM2.5 have an 11 percent greater risk of dying from heart attacks, strokes and heart failure than those who live in cleaner areas.

Dr. Robert Brook, a cardiologist at the University of Michigan Health System and another author of the policy statement, said many people don’t realize the dangerous effects of air pollution on the heart.

“While most people can readily observe and believe that air pollution may cause lung diseases, it is in fact cardiovascular diseases that are the largest adverse health effect of fine particulate matter exposure,” Brook said in an email.

Dr. Alan Abelsohn of the Dalla Lana School of Public Health at the University of Toronto in Canada, called the statement an important reminder. Too few cardiologists and primary care doctors advise their patients of pollution’s risks, he said.

“It’s a very important and neglected area of prevention,” he said.

Abelsohn, who was not involved in the position statement, noted that national-level guidelines on allowable amounts of pollution can only do so much. He said individuals should always pay attention to the local Air Quality Index, which rates the level of air pollution according to health risk, and reduce their exposure accordingly.

Brook said that while the U.S. has made great strides reducing air pollution since the 1970s or even 2000, the efforts should continue.

“What we should not do is lessen our regulations and pose a threat to the cardiovascular health of the nation in the name of expediency or supposed economic growth or stimulus,” Brook said.