01:07 - Source: CNN
How deadly is air pollution?
CNN  — 

Even when air pollution is at levels below air quality guidelines and regulatory limits, it can still pose a hazard to public health, a new study finds.

In a 30-year analysis of 652 cities in 24 countries and regions on six continents, researchers found that increases in air pollution were linked to increases in related deaths. The study, published Wednesday in the New England Journal of Medicine, was one of the largest international studies to look at the short-term impact of pollution as a cause of death, the researchers said.

The analysis of air pollution data from 1986 through 2015 found there were increases in total deaths linked to exposure to inhalable particles and fine particles. The deaths were from cardiovascular and respiratory problems.

Particle pollution is the mix of solid and liquid droplets in the air, according to the US Environmental Protection Agency. It can come in the form of dirt, dust, soot or smoke. It comes from coal- and natural gas-fired plants, cars, agriculture, unpaved roads and construction sites.

With higher levels of pollution, the faster people are dying, said Chris Griffiths, a professor of primary care at Queen Mary University of London.

“These are avoidable deaths. Most concerning is that deaths relating to pollution occur at levels below international recommended pollution limits,” Griffiths told Science Media Centre. “The authors provide the strongest evidence yet that target air pollution levels are set too high.”

Health effects of air pollution

A study in July found that long-term exposure to air pollution, especially ground-level ozone, is like smoking about a pack of cigarettes a day for many years and can cause problems such as emphysema. Another study found that it can cause COPD and age lungs faster. Air pollution also increases the risk of heart disease, stroke and lung cancer.

Earlier studies predicted exposure to ground-level ozone concentrations could lead to millions more acute respiratory problems and would cost the United States billions of dollars. Exposure to air pollution caused more than 107,000 premature deaths in the United States in 2011 alone, research has found.

Under the Trump administration, pollution guidelines have gotten looser. The administration’s recent guidance to states would allow a state to emit 43% more pollution across state lines than before, even though the agency itself said it could result in 1,400 more premature deaths by 2030 than the Obama-era plan it is replacing. States have asked the federal courts to block the administration’s overhaul of these rules.

Get CNN Health's weekly newsletter

Sign up here to get The Results Are In with Dr. Sanjay Gupta every Tuesday from the CNN Health team.

President Donald Trump has said that it’s been a “top priority” to make sure “America has among the very cleanest air and cleanest water on the planet,” but since he has been in office, the number of “unhealthy air days” has increased, according to the Environmental Protection Agency. “Unhealthy air days” occur when the level of ozone or particulate matter is high enough to be a danger to kids, the elderly or people with lung problems.

That may in part be related to the administration’s roll back of dozens of environmental protections. Trump has also moved to freeze vehicle emission standards and pull out of the international Paris climate agreement. After years of decline, US carbon emissions have risen sharply, according to 2018 data. Carbon emissions are the main driver of climate change.