Smoggy Skies May Cause Respiratory Death
A smoggy skyline in Los Angeles - The downtown skyline of Los Angeles, enveloped in smog in 2006. Los Angeles is the second smoggiest city in the U.S, according to a new study in the
People living in the smoggiest cities are 30 percent more likely to die from respiratory diseases, including pneumonia, than those living in the least smoggy areas, according to a new study published in the New England Journal of Medicine.
The nationwide study of 450,000 adults is the first to document the long-term impact of ozone on human health.
It's estimated that 100 million Americans — or 1 in 3 — live in cities with unhealthy levels of ground-level ozone. Ground-level ozone — the major component of smog — forms when tailpipe emissions combine with sun and hot air. Smog season runs from April through October in Southern California, and is slightly shorter in cooler regions of the country, such as the Mid-Atlantic and Northeastern states.
(David McNew / Getty Images)
Dangers Of Ozone
Researchers and physicians have known for many decades that spikes in air pollution during the summer months cause health problems. Asthmatics experience more flare-ups, and there are more hospital admissions for respiratory ailments and heart attacks.
The new study provides the first evidence that long-term, chronic exposure to elevated levels of ozone significantly increases the risk of death from respiratory diseases.
(David McNew/Getty Images)
"The study points to the fact that there may be a three-fold increased risk of dying from respiratory disease in the smoggiest areas of the country," says Dr. John Balmes of the University of California, San Francisco.
The adults in the study, originally recruited by the American Cancer Society, were tracked for 18 years. During this time, about 118,000 people died. Michael Jerrett, a researcher at the University of California, Berkeley and his colleagues then teased out the causes of death. They documented that people living in the smoggiest cities were more likely to have died from lung diseases such as chronic bronchitis, emphysema and pneumonia.
Jerrett and his team controlled for 44 individual factors that may have influenced the results, such as smoking, alcohol consumption, occupational exposures, unemployment status and income. But even after that, he says, "We still see a very strong and clear signal that people in high-ozone areas are at higher risk of death."
Limiting Smog
During the summer smog season, people with respiratory conditions such as asthma are told to stay indoors. And some cities offer free public transportation on days when ozone levels are extremely high.
But other than staying indoors, there are few ways to limit chronic, cumulative exposures.
"We know that ozone causes inflammation of the airways," explains Balmes. "And that chemical burning makes people more susceptible to infectious agents like viruses and bacteria that cause pneumonia."
If people are interested in reducing smog, experts say the best thing they can do is to drive less, especially during the summer months.
Most emissions in the smoggiest cities come from cars and other vehicles.
Another way to cut ozone is to change federal regulations. Current clean-air laws, which helped reduce smog throughout the '80s and '90s, were aimed at preventing summertime spikes.
"The law of the land restricts the peak levels on the highest days of the year," says George Thurston of New York University's Langone Medical Center.
Given the new evidence, advocates will likely push for a new "annual average" standard that aims at further reducing the overall burden of smog.
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MICHELE NORRIS, host:
From NPR News, this is ALL THINGS CONSIDERED. I'm Michele Norris.
ROBERT SIEGEL, host:
And I'm Robert Siegel.
None of us likes to hear that we are aging prematurely, but according to a new study in the New England Journal of Medicine, the smoggy air that many of us breath is both damaging and aging our lungs.
As NPR's Allison Aubrey reports, that means that people exposed to high levels of ozone over their lifetime are significantly more likely to die from lung disease.
ALLISON AUBREY: If you happen to be listening to this broadcast in Los Angeles, Houston, New York, Washington or Baton Rouge, raise your hand. Okay, don't, actually. But do imagine this. If all the hands of people living in smoggy ozone-polluted areas went up, we'd have 100 million arms raised. That's how many Americans live in places with unhealthy levels of ozone.
Dr. JOHN BALMES (Professor of Medicine, University of California, San Francisco): That is a lot of hands, it's a third of the population of the country.
AUBREY: John Balmes is professor of medicine at the University of California, San Francisco. He says, we've known for a long time that summertime spikes in smog cause health problems. Kids with asthma get flare ups, hospital admissions for respiratory diseases increase. But this new study provides evidence that cumulative exposure to elevated levels of ozone over the long term is more dangerous than we knew.
Dr. BALMES: The study points to the fact that there may be a three-fold increased risk of dying from respiratory disease in the smoggiest areas of the country.
AUBREY: Living in a smoggy city, breathing smoggy air actually increases your risk of death?
Dr. BALMES: Yes, that's true. And this is really the first study to provide convincing evidence of that.
AUBREY: So here are some details about the study. It included 450,000 adults who were followed for almost 20 years as a part of an American Cancer Society study. During these two decades, about 118,000 people died. When researcher Michael Jerrett of UC Berkley and his colleagues teased out the causes of death, they realized that people living in the smoggiest cities were 30 percent more likely to have succumbed to lung diseases such as chronic bronchitis, emphysema and pneumonia.
Dr. MICHAEL JERRETT (Researcher, University of California, Berkeley): That's even after we control for 44 individual factors like smoking, alcohol consumption, occupational exposures. A number neighborhood factors like unemployment and poverty. So even when we control for all of those variables that can affect mortality, we still see a very strong and clear signal.
AUBREY: So how can people cope during the summer smog season when the problem is acute? People with respiratory conditions such as asthma know to stay indoors. Also, some cities offer free public transportation on red alert days. But when it comes to chronic cumulative exposures that this study shows to be dangerous, physician John Balmes says there's not a lot individuals can do.
Dr. BALMES: We know that ozone causes inflammation of the airways and that chemical burning of the airways makes people more susceptible to infectious agents like bacteria or viruses which cause pneumonia.
AUBREY: If people are interested in reducing smog, experts say the best thing they can do is to drive less, especially during the summer months. Most emissions in the smoggiest cities do come from cars and other vehicles. Another way to cut ozone is to change federal regulations. Researcher George Thurston of New York University says the clean air laws that helped reduce smog throughout the '80s and '90s were aimed at preventing summertime spikes.
Dr. GEORGE THURSTON (Researcher, New York University): The law of the land was that they restricted the peak levels on the highest days of the year.
AUBREY: Given the new evidence, there will likely be a push for a new annual average standard aimed at further reducing the overall burden of smog.
Allison Aubrey, NPR News, Washington. Transcript provided by NPR, Copyright National Public Radio.
