Heart Attacks
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Doctors at the Harvard School of Public Health looked at the timing of over 700 heart attacks in the Boston area. They learned that the risk of heart attack climbed by as much as 70 percent during spikes of high pollution, especially when the particulate count was high.

Particulates are tiny airborne particles made up largely of soot, acid, and dust. At first, they weren't considered a major health risk, but now we know that particulates can be deposited deep inside our lungs. Scientists think this may trigger an inflammation response that slows our blood and makes it clot more easily. This could be why particulates seem to trigger heart attacks, especially in the first 24 hours after particulate levels go up. The Harvard study found that heart-attack risk goes up even if particulate levels are just below the EPA's 24-hour standard, set in 1997.

How do you protect yourself? The researchers suggest that if you're at high risk for cardiovascular trouble, you stay in an air-conditioned building as much as possible when the weather gets hazy, hot, and polluted. The air conditioning could help filter the air so that fewer of the tiny particulates get indoors and get inside your lungs.

Thanks today to writer Bob henson of Boulder, Colorado. The Weather Notebook is a production of the Mount Washington Observatory and supported by the National Science Foundation.