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Few of us probably think about the implications of living in an area with smog or heavy air pollution. But new research from the American Heart Associations (AHA) suggests we might want to think twice about air quality when deciding which city to call our home. Regular exposure to ground-level ozone, the major component of smog, may trigger cell death in the heart, according to their preliminary research in rats.
Ozone (O3) is a gas made of oxygen molecules. In the upper atmosphere, it protects the earth from the sun's radiation. Chemical reactions between industrial air pollution and sunlight cause the formation of ground-level ozone and smog. That’s why smog occurs most often in urban or industrial areas, and during the sunniest summer months.
In the study, rats that were exposed to high levels of O3 showed increased activity of a substance that prompts cell death in the heart, which can lead to heart failure.
For the study, scientists tested four groups of 10 rats living in clear boxes. The first two groups were exposed to ozone, or O3, for eight hours a day for 28 or 56 days, respectively. The other two groups were given clean, filtered air for eight hours a day for 28 or 56 days. During the remaining 16 hours of each day, all of the rats’ boxes were pumped full of clean air. The rats subjected to ozone had increased levels of inflammation markers that lead to lower levels of a heart-protective protein called Caveolin-1 (Cav1). Without Cav1, a death-signaling chemical called p38MAPK α can run amok and tell cells in the heart to die.
That doesn’t necessarily mean that if you live in Los Angeles, a city synonymous with smog, your heart’s cells are committing hari kari on a daily basis. The amount of ozone that the rats were exposed to -- 0.8 parts per million (ppm) -- far exceeds the amount any of us breathe every day. According to the Environmental Protection Agency’s National Ambient Air Quality Standards (NAAQS), average ground-level ozone concentrations within a specific area must not exceed 0.075 ppm, one-tenth of the amount used in the lab.
This study is one of the first to parse out which particular air pollutants may lead to heart-health problems. Earlier this year, the AHA released a statement saying that even short-term exposure to air pollution can cause heart attacks in susceptible people (meaning, those with heart disease or other cardiac issues). According to this most recent report, 60,000 out of 350,000 sudden cardiac deaths in the U.S. have been linked to air pollution. The study’s authors hope their research will help guide policies regarding safe air quality standards.
If you have a history of heart or lung problems, it’s a good idea to limit your exposure to smog and other pollutants by staying indoors when the air quality index (AQI) hits 101 ("unhealthy for sensitive groups") or above. You can check the AQI for your area at Airnow.gov.
Carpooling? Biking? Being energy-efficient? What are you doing to reduce air pollution in your neighborhood? Chime in now!
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