Air pollution contributes to as many as 10% of all deaths in Minnesota every year, while sending an additional 1,300 people to the hospital with heart and lung problems.
And the threat isn't confined to major cities. Airborne contaminants harm residents in every part of the state, especially the elderly, the poor, children with asthma, the uninsured and people with pre-existing medical conditions, according to a joint analysis released Tuesday by the Minnesota Department of Health and the Minnesota Pollution Control Agency (MPCA).
"This really reflects that it's not just a big city issue anymore, but you see it in these certain vulnerable populations," said Kathy Raleigh, a principal epidemiologist with the Health Department.
While it's no surprise that pollution is harmful to human health, over the past several years state health and air pollution officials have tried to calculate its toll on the public. In 2015, the state released a first-of-its kind study that focused on the Twin Cities and found that two of the most common pollutants — fine particles and ozone — contributed to as many as 2,000 deaths a year in the metro area alone.
Expanding that study to the entire state this year, researchers found that the death rate attributable to air pollution was actually higher in rural areas than in cities and was particularly bad in southern Minnesota and along the state's border with South Dakota. That's in part because those areas have higher proportions of older adults and people who are uninsured than the metro.
It also shows that air pollution, once considered primarily an urban problem, now afflicts the entire state, Raleigh said.
"We see some higher fine particle matter in the metro, and then ozone has been a little higher in southern Minnesota, but air pollution across the state doesn't change a lot," she said.
What does change, she said, is the underlying conditions of the population. The report found that pollution aggravates existing health problems such as heart and lung disease. It tracked hospital visits and deaths caused by heart and respiratory events and compared them with the annual air quality of each county. It estimated that pollution contributed to between 2,000 and 4,000 deaths throughout a single year.
Air quality has generally been improving since Congress passed the Clean Air Act in the 1970s. Some of the biggest gains have come recently from power plants, as more and more shifted from coal to natural gas. A majority of the most harmful air pollutants are now coming from smaller and more widespread sources such as cars, trucks and backyard fires, which are not regulated in the same ways as factories and power plants, according to the MPCA.
Minnesota has reduced fine particle pollution by about 10% over the past decade, according to the agency's data. The report estimates that if the state reduces those levels by another 10% it could prevent up to 500 deaths and more than 100 hospitalizations and emergency room visits annually.
However, some of the worst pollutants are now generated outside the state and carried in by the wind from events such as the wildfires in Canada and the Pacific Northwest.
It's not enough to just cut pollutants within the state, Raleigh said. More needs to be done to help make vulnerable residents more resilient.
"We can see those populations with a higher percent in poverty and higher percent uninsured are more vulnerable," she said. "If we can do more to decrease those structural inequities, those barriers, that will lay the foundation."