Hurricane Katrina's early health effects were the stuff of high drama: overflowing Superdome toilets, violence between city residents, hospitals without power or water, and dehydrated flood victims stranded on roofs.
But, says Patrick Kinney, while it's easy to draw a straight line between climate change, stronger hurricanes, and the flood crisis in New Orleans, the most worrying health effects of climate change are more insidious. Kinney, an epidemiologist at Columbia University's Mailman School of Public Health, studies the respiratory effects of air pollution. He examines how diesel pollution triggers asthma attacks, why rising carbon dioxide levels could worsen hay fever, and what happens when ground-level ozone irritates our lungs. His research has taken him from the air of New York's high schools to the smoke of Africa's cooking fires.
He's also keeping an eye on the air in New Orleans. After Katrina, people returning to damp homes breathed mold-laden air that irritated their lungs, he says. Other New Orleanians took refuge in hastily built mobile homes, where they inhaled the carcinogen formaldehyde leaching from shoddy particle board. "There were a myriad of cascading impacts over time," Kinney says.
Kinney spoke in Boston at the February 2008 meeting of the American Association for the Advancement of Science. Afterward, he explained his findings in a quiet, urbane voice, his bright blue eyes lighting up at key moments.
Is there a cause-and-effect relationship between air pollution and children's asthma?
There's been a lot of controversy. It's still not clear whether being around air pollution makes you more likely to get asthma. But it's certainly true that if you have asthma, and you're exposed to more pollution, you're more likely to have an asthma attack. The asthmatic response really varies, depending on the person and what triggers it.
What happens in an asthma attack?
The tubes in the lung have muscle in their walls. The muscles tighten up to make the tubes smaller. It's hard to get air in and out. That's immediate. The second thing that takes a little bit longer — hours — is inflammation. The lining of the airways gets inflamed and red and swollen. That adds to the narrowing. Ongoing inflammation can permanently alter the structure of the lung, because the inflammatory cells are trying to fight off an enemy that's not really present. They're spewing out toxic things, and that's chewing up the lung.
What has your research shown about how pollution feeds into asthma?
A lot of my research has focused on traffic. There is something about traffic pollution from cars, and especially from trucks and buses — diesel particles — that seems to have a special role in exacerbating asthma. It really does seem to matter whether you live on a busy road or not. That [finding] will hopefully have some impact on siting of schools and residences near busy roads, or convince us to reduce emissions more, so that you can have a busy road near a residence without endangering people's health. We've also done work on indoor pollution in New York, focusing on both pollution and allergens. In New York, we have a lot of asthmatics who are allergic to cockroach particles, which are very allergenic, and also mouse feces and dander.
In addition to health problems from large weather events, like Hurricane Katrina, what other respiratory problems may arise as a result of climate change?
Ground-level ozone will go up a little bit, because it forms more rapidly when air temperatures increase.
What does ground-level ozone do when we breathe it?
It causes inflammation of the airways.
In everybody, or just in people with asthma?
No, it pretty much causes inflammation in everybody. But asthmatics will be affected more — they already have inflammation, and that will be augmented. To a healthy person, it might not be noticeable. It's important to keep in mind the difference between ground-level ozone and ozone in the stratosphere. In the stratosphere, ozone is desirable. We worry about losing it. But ozone's not a good thing to breathe. Nitrogen oxides, or NOX, and volatile organic compounds, or VOCs, come out of tailpipes, and also out of our gas tanks. VOCs and NOX together, in the presence of sunlight, form ozone. The only things we can control are the NOX and the VOCs. The sunlight comes and goes however it wants.
When we have more carbon dioxide down at ground level, does it change what plants are doing?
Plants are generally happier in higher CO2, because they use it, so most plants grow better at high CO2. But what they do with that extra growth varies from plant to plant. In the case of ragweed and poison ivy, two plants that have been studied, they produce more of their nasty stuff.
They produce more pollen, more toxins?
Yes. Also, food crops, even though they may get leafier and happier, don't produce as much protein. Protein is the thing that limits places that are malnourished in the world. It's pretty remarkable that the nasty plants are doing more of their nasty stuff and the important agricultural plants are being compromised.
"There is something about traffic pollution from trucks and buses — diesel particles — that seems to have a special role in exacerbating asthma. It really does seem to matter whether you live on a busy road or not. That hopefully will convince us to reduce emissions more, so you can have a busy road near a residence without endangering people's health."
What do you think are the health implications of climate change for the developing world?
Cities are growing rapidly in the developing world, and there's more and more car use in those cities. There are a lot of dirty vehicles — you see the black smoke coming out of the tailpipe. In Los Angeles, I saw a school bus go by that had black smoke coming out.
Oh gosh.
School buses in California still haven't been controlled.
That's very surprising.
I was shocked. It went right by UCLA. The guy I was with, who studies that problem, said that we've been trying, but whoever runs the school buses is hard to crack. In the developing world, most vehicles are like that. And it's getting worse and more congested. I think so far it's not recognized as an important concern; people in those countries don't notice the air pollution. They don't think of it as a health issue. There is very little local health or air pollution data. Based on what we know in the U.S. and Europe, you would guess that their health is being impaired. Then the question becomes "How much?" And how does it compare to other health threats faced in the developing world? With that kind of information, the policymakers there could decide whether it's worth dealing with. It's time to start gathering the data. I've been starting to work in Africa, but it's really amazing how little has been done.
I've read a fair amount about food allergy. One hypothesis is that an increased rate of food allergies is due to children living in cleaner environments, that they're not exposed to enough allergens, that their parents are too paranoid about keeping everything clean. It seems that might conflict with some of your findings of respiratory problems resulting from exposure to more allergens. Do you think there's a conflict?
That is a very confusing picture. There's been a lot of research on the role of early life exposures in the development of allergic asthma. There's a prominent theory about the rise of asthma that says during early life children are not exposed to as much stuff as they used to be. But it's not a question of allergens that they're not getting enough of, it's exposure to infectious germs. Catching a lot of colds that your immune system can fight off early in life apparently keeps you from going towards a self-inflammatory phenotype. Evidence here comes from looking at low asthma rates in places where kids are running around in the dirt and being exposed to intestinal worms. Those kids don't get asthma. Also, kids who go to day care within the first 6 months of life get a lot of respiratory infections, but they don't get asthma as much as kids who don't go to day care.
Where do you see your research going in the next five to 10 years?
I hope I'll be doing more work on climate change, probably focused on health effects related to air pollution and also pollen and mold. [I'll be] staying in the air pollution area in general, but going beyond the usual ozone pollutants. And I'm doing a lot of developmental work on African indoor and outdoor air quality. I have a proposal [to the National Institutes of Health] to do a study on the effects of cooking with biomass fuels on women and children in Ghana. It's very smoky, so it's a very large exposure to the women who are cooking. When they're pregnant, that's probably having effects on the baby. We have a study planned to examine that question.
As we use more nanotechnology, what might the public health effects be?
Nanoparticles have the potential to be toxic, because they can get very deep in the lungs. I forget what it's called, but there's a carbon tube that's very, very narrow, but it's very, very long. Nobody knows anything about the toxicity, but it looks a lot like an asbestos fiber. And we know that asbestos fibers are difficult for the lungs to process. Macrophages [the scavengers of the immune system] can't engulf them. They can bite off a little piece, but they can't digest them. Then the macrophage dies and spills its enzymes, which cause more inflammation, and it just becomes a big mess. So I think it's a big concern. We need the research.
Erin Digitale, a graduate student in the Science Communication Program at UC Santa Cruz, earned a B.S. in biochemistry from the University of British Columbia and a Ph.D. in nutrition from UC Davis. She has worked as a reporting intern at the Salinas Californian, KUSP public radio in Santa Cruz, and the San Jose Mercury News. Erin's summer internship is at the news office of the Stanford University Medical School.
© 2008 Erin Digitale
