Clearing the Air on Climate and Smog

Why climate change and public health policy make good chemistry

(October 21, 2011)

A major study released today in Fresno details the direct link between higher levels of air pollution and asthma-related ER and hospital admissions. So, what’s that got to do with climate change? Plenty.

“There’s a division in the public’s mind between global warming and health effects of pollution,” says Dimitri Stanich of the California Air Resources Board.

In reality, there’s significant overlap. Some components of air pollution shown to have harmful warming effects on the planet are also harming people, especially children, right now.

Let’s start with ground-level ozone. Ground-level ozone is different from the ozone layer, which lies about 15 miles above the earth (not exactly ground level). The ozone layer shields us from most of the sun’s harmful rays. Ozone is good in the atmosphere but bad, in many ways, at or near ground level.

Ground-level ozone is not part of air pollution itself. Instead, it is formed by a complex chemical reaction starting with the nitrogen dioxide (NO2) component of air pollution. That chemical reaction is especially strong when the air is calm and the sun is shining (California’s Central Valley in the summer, anyone?). This stuff is terrible for your lungs.

“Ozone has the same corrosive aspects of bleach,” explains Bonnie Holmes-Gen, senior policy director for the American Lung Association in California. “When people breathe it in, it damages the lining of the lungs. It’s like getting a sunburn on the lungs. It triggers coughing, wheezing and asthma attacks,”

Ground-level ozone is also a greenhouse gas. So, while it’s harming people today, it’s simultaneously helping to warm the planet. If that’s not enough, ground-level ozone’s corrosive properties harm crops, too. The Central Valley may be the nation’s salad bowl, but it’s ground zero for ground-level ozone.

Then there’s "black carbon.” If you think that sounds ominous, you’re right.Tiny particles of black carbon can lodge deep in a person’s lungs (bad) or circulate in the air and contribute to global warming (also bad). And, in a triple whammy, if black carbon particles land on arctic snow, they can accelerate the ice melt. Scientists say black carbon is a major contributor to climate change, perhaps second only to CO2. Black carbon comes from, among other things, the burning of fossil fuels, the stuff that comes from tail pipes and smokestacks.

Sunday’s New York Times featured a depressingly detailed account of Americans’ waning interest in global warming. Climate skepticism is on the rise, at least in political circles. While skepticism about the health effects of air pollution isn’t polled as much, it seems reasonable to think there’s little argument there.

This is where we get to what policymakers call “co-benefits.” Ms. Holmes-Gen points out that ground level ozone and black carbon are both fairly short-lived in the environment. “It’s a huge bang for the buck. If we reduce air pollution, we’ll see an immediate health benefit and we get warming pollutants out of the air, too.”