Asthma exacts a terrible toll on American children. One in twelve US children have asthma, for a total of more than 6 million children. It is the most common chronic disease of childhood; the leading cause of missed school days; and it drains the US economy to the tune of $82 billion each year.
Air pollution has long been known to make asthma worse, triggering asthma attacks among children who have the disease. Less well-studied is whether air pollution causes the disease to develop in otherwise healthy children. In other words, we know that breathing air pollution can make asthma worse, but can it actually cause asthma?
A growing body of evidence points toward yes. And it’s not just air pollution in general. Specifically, it’s the pollution that comes from cars, trucks, and buses – traffic pollution – that seems to cause asthma. This adds to longstanding health concerns about living, working, studying, and playing near traffic-related air pollution.
Two new studies take a closer look at this problem. One, published in The Lancet this month, estimates that globally, traffic pollution causes 4 million new cases of asthma in children each year. 64% of those cases are urban centers. This preventable pollution accounts for 13% of all new asthma cases worldwide.
Another study from researchers at Texas A&M University focuses in on the US, and analyzes how many cases of new asthma can be attributed to traffic pollution each year – and how that disease burden differs by area. The study, published in the journal Environment International this month, uses levels of NO2 (nitrogen dioxide) as a proxy for traffic pollution. It shows that in 2010, traffic pollution caused 18% of all new cases of childhood asthma in the US. This is considerably less than for 2000, when traffic pollution was responsible for 27% of new cases. This decline represents improvement in air quality and reductions in traffic pollution.
Yet despite good progress, this preventable environmental cause of asthma is devastating. With new cases of asthma in the hundreds of thousands each year, these percentages represent a staggering number of cases. In 2000, NO2 pollution was responsible for 209,000 new cases of asthma in the US; in 2010, it was responsible for 141,000 cases. The burden is especially severe in urban areas, where large number of children live and where traffic pollution is the worst.
These are preventable cases of new asthma in children – asthma that is unrelated to genetics, allergies, or other factors. Reducing the pollution coming from the tailpipes of cars, trucks, and buses could slash new cases of the disease. Meanwhile, the Trump administration is rolling back and weakening pollution protections of all kinds, including those that require the transportation industry to improve. As this new study makes all too clear, these regulatory rollbacks are a direct threat to the health of our families.
Researchers made a map of the problem, so you can see how many cases of asthma are caused by air pollution every year where you live.
My city, Washington DC, is one of the hot spots for asthma from traffic pollution in 2000, and still appears in deep red for the 2010 map, when much of the rest of the country has shifted to green. Scrolling over the map, I can see that traffic pollution caused 297 cases of asthma to develop in 2010, representing 27% of new cases of asthma.
What’s happening in your city?