Ample research shows bad air can hurt you — and not just your lungs

Say you’re asked about the factors that affect your health. What do you point to? Exercise, the stuff you eat and drink, the genes your parents passed down to you?

What’s in the air you breathe might not even cross your mind. But air pollution is a health risk for people in communities across the United States.

That’s not a problem of the past or only of developing countries, despite big gains in U.S. air quality in recent decades. We all have to breathe, but we don’t all breathe the same air, thanks to variations from place to place. On top of that, researchers keep finding health risks at lower pollutant levels and new ways in which air pollution can sicken us.

I’m excited to be part of the 2016 National Health Journalism Fellowship because I want to write two stories that each focus on a different aspect of how air affects us — some of us more than others. A colleague and I are crunching national datasets for the analysis that will underpin these pieces.

More than two decades ago, Harvard University researchers showed in a groundbreaking study that people living in areas with worse air died earlier than people in cleaner communities, even after accounting for smoking and other key determinants for health. New research keeps coming out about air pollution’s effects. Here’s a small sampling:

• Lung problems. Many kinds of pollutants are bad for the lungs, including ozone (also known as smog), the tiny specs of toxic mixtures called fine particulate matter, and a variety of industrial emissions. Pollution can harm lung growth in children, trigger asthma attacks and increase the odds of developing respiratory diseases in the first place, according to the National Institute of Environmental Health Sciences. The good news: A University of Southern California study of children in the 1990s and more recently, released in 2015, found better lung development in kids as the air in the southern part of the state improved.

• Heart disease. Cardiac arrest — when the heart stops beating — is more common on days when ozone spikes, research in Texas suggested in 2013. That’s a sudden shock to the system, but pollutants can have a long-term effect, too. A widely hailed new study, led by a University of Washington doctor, followed more than 6,000 participants over a decade and showed that people exposed to higher levels of fine particulates had faster rates of the calcium deposits known as hardening of the arteries, a major cause of heart attack and stroke. The study found the same effect for nitrogen oxides, gases emitted by vehicles and industrial facilities.

• Neurological effects. Certain heavy metals that can be puffed out of smokestacks, such as lead, have long been understood to have negative effects on the brain. But some of the newest research on air pollution is aimed at figuring out whether common contaminants — such as fine particles or the even smaller “ultrafine” particles — play a damaging role. Several studies, including Harvard research published in 2015, suggest a link between fine-particle exposure and the developmental conditions known as autism spectrum disorder. Newly released research out of Sweden found that children living amid higher levels of the traffic pollutant nitrogen dioxide were more likely to be on psychiatric drugs, raising the possibly of a link “even at the relatively low levels of air pollution in the study regions.”

• In utero damage. Pregnant women with more exposure to fine particles are also more likely to have intrauterine inflammation, a major cause of premature birth — which can have lifelong, sometimes serious effects for the child born too early. That’s what researchers concluded in an April study of about 5,000 mother-baby pairs in the Boston area, which has relatively clean air overall. (“This study raises the concern that even current standards for air pollution may not be strict enough to protect the fetus,” lead author Rebecca Massa Nachman of the Johns Hopkins University said in a statement.) Another study estimated that more than 15,000 U.S. premature births in 2010 could be blamed on the air. Some studies (here’s one, and here’s another) have also suggested links between certain air pollutants and infant mortality.

• Cancer. Outdoor air pollution, the International Agency for Research on Cancer concluded in 2013, is a carcinogen — a significant cause of the world’s lung cancers. A 2013 UCLA study of California children found a possible link between traffic emissions and three rare childhood cancers, including leukemia. And research released in April that followed 66,000 elderly Hong Kong residents for at least a decade found an association between air pollution and cancer deaths generally — from the breast to the digestive tract. (U.S. air is decidedly better than Hong Kong’s, but co-author G. Neil Thomas of the University of Birmingham in the U.K. suspects the findings are relevant for lower levels of pollution, too.)

The idea that what you inhale can affect your lungs is perfectly logical. Less obvious is how the air you breathe could contribute to other diseases, something researchers have long worked to understand.

One reason suggested in many studies is that air pollution triggers inflammation, which can lead to a variety of ill effects.

Michelle L. Block, an environmental neurotoxicologist at the Indiana University School of Medicine, is researching how air pollution “sticks its finger in and stirs the hornet’s nest up” in the brain. What she’s finding is that air pollution reprograms brain immune cells called microglia to make them “exceptionally sensitive” to mild inflammatory and central nervous system disease triggers. A May study she co-authored with researchers from across the country suggests that lung effects from air pollution may be enough to shift the microglia in this way — a domino effect.

“We very strongly believe that lung health itself is impacting the brain,” she said.     

Dr. Joel Kaufman, a University of Washington medical doctor and epidemiologist who led the newly released cardiovascular study, takes heart in the public-health success of much better air, on average, than Americans breathed a generation ago. It has yet to reach the point of no ill effects, though.

And as his recent study shows, the differences in air quality across the country — and even across a community — have consequences. For hardening of the arteries, Kaufman said, air pollution’s effect is similar to “diet and exercise — and those other things over which people are flogged.”

[Photo by Christopher A. Dominic via Flickr.]