Clear Air, Calm Hospitals

We care about the air we breathe because poor air quality can be harmful to our health. People can end up in the hospital when they breathe polluted air. Many countries, including the US, have regulations to reduce air pollution in an effort to improve the health of residents. When trying to convince businesses to improve air quality, it helps to have proof that taking the required steps actually leads to improvements in health. There is a “chain of accountability” that includes regulations, emissions, air quality, exposure, and health effects. Ideally, the evidence will cover all of these steps. There has been lots of research that focuses on two or three steps in this chain. We know that regulations reduce emissions, that emissions affect air quality, and that exposure leads to health effects. This paper makes a connection between all of the steps at once.

More Data, More…Answers

Dr. Henneman and his colleagues at Harvard looked at air pollution and emissions from coal fired power plants between 2005 to 2012. Due to environmental regulations aimed at reducing air pollution that were implemented during this period, emissions from the coal fired power plants decreased. The EPA collects data on emissions from power plants to better understand what’s being released into the air and to make sure the power plants are complying with the current environmental regulations. Using the emissions data and computer simulations, researchers determined which zip codes in the US were affected by pollution from power plants. They also figured out what type of air pollution people in each zip code were exposed to. Millions of people use the Medicare program so the researchers also had a large database of people who visited the hospital from different zip codes during the same time period. To conduct their study, the scientists  used statistics to compare air pollution exposure to hospital visits by Medicare patients.  

Not Feeling So Good

The researchers looked at several different diseases (such as breathing disorders and heart disease) that are associated with air pollution. Some diseases did not decrease even when total air pollution and air pollution from the coal plants decreased. These diseases might be strongly affected by other sources of air pollution, such as vehicle traffic. 

However, several diseases actually were reduced when total air pollution went down. Cardiovascular disease, strokes, heart failure, and respiratory tract infections were all reduced when the total exposure to air pollution went down. This association suggests that reducing exposure to coal emissions or total air pollution will reduce the incidence of those diseases. 

Emissions Sources include cars and power plants.
A photo showing multiple sources of air pollution, both electricity generation and a car traveling on a road. (Source: Wikimedia Commons)

Chronic obstructive pulmonary disease (COPD) includes conditions that make it hard to breathe, such as emphysema and chronic bronchitis. While total air pollution reductions did not always lead to improvement in COPD, there was a strong association with decreased coal emissions and a decrease in COPD. This means that emissions from coal fired power plants in particular are important to reduce to improve this health outcome. This is really useful information as we consider how to improve health in the future.

Studies like this provide more information to help us make better choices for our future health. By identifying not only that pollution affects health, but which pollution sources are important, we have more information to make important health decisions than we did before. US air quality regulations have improved both air quality and health, which is great news for the EPA, the federal agency that protects human and environmental health and  celebrates its 50th birthday this year. That’s five decades of a cleaner environment and healthier people. 

Source Article: Henneman, Lucas RF, Christine Choirat, and Corwin M. Zigler. “Accountability assessment of health improvements in the United States associated with reduced coal emissions between 2005 and 2012.” Epidemiology 30.4 (2019): 477-485.

Header Image: Emissions from a coal fired power plant. Source: Flicker.

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Kristen Brown

Kristen Brown

I am a postdoctoral researcher at the EPA where I specialize in evaluating environmental impacts of our energy system. I have a PhD in Environmental Engineering from CU Boulder where I also received a master’s in Mechanical Engineering, and I have a BA in Physics from Cal Berkeley. Outside of work, I’m an amateur boxer and have two spoiled dogs. You can follow me on twitter at @Kris10BrownPhD and find out about my research at

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