The same mechanism that makes greater numbers of people keel over dead of heart attacks and strokes when microscopic air-pollution levels spike in cities across the United States has researchers voicing their concerns about the heavily polluted air in Beijing.
And they're not just worried about the athletes. They're concerned that the bad air might trigger cardiovascular problems for people in the stands. Even if the spectators survive the games, they might be at higher risk of developing a blood clot while sitting through the plane ride home.
In 2007, researchers at Northwestern University solved the mystery of why greater numbers of people were dying from heart attacks and strokes within 24 hours of a spike in the level of tiny particles that spewed from diesel trucks, buses and coal-burning factories. Scientists knew cardiovascular problems went up with air pollution levels, but they didn't understand the mechanism.
What researchers, including lead author Dr. Gokhan Mutlu, pulmonary and critical care specialist at Northwestern Memorial Hospital, found was that the small particles -- less that one-tenth of the diameter of a human hair -- inflame the lungs, which then secrete a substance, interleukin-6, which causes blood to coagulate. It raises the risk of a fatal heart attack or stroke for people with coronary artery disease, congestive heart failure or a history of stroke.
Now that they know how and why it happens, they're pretty worried about travellers to Beijing. "If you spend a few weeks in Beijing, your blood might become thicker and sticky and then when you fly 12 hours back to the U.S., that further increases your risk," Mutlu says in a news release. "If clots migrate into the lungs and cause pulmonary embolism, that can kill you."
The BBC has been tracking levels of small-particle pollution for two weeks on a daily Beijing pollution watch photo gallery. So far, it's gone from a good day on July 12 of 8 micrograms per cubic meter to a very bad day two days later of 255 micrograms per cubic meter. (You can find out how bad average particle pollution is in your state and county at the American Lung Assn.) The U.S. Environmental Protection Agency recommends a daily limit of no more than 30 to 35 micrograms per cubic meter -- a level many American cities, and at least nine counties in California, fail to meet.
But it's worse in Beijing. Dr. Scott Budinger of Northwestern has some suggestions for people who will be flying to China for the Olympics.
1. Men over 40 should take an aspirin each day to prevent their blood from becoming thick and sticky. Though the benefits of aspirin are less certain for women, it probably wouldn't hurt for them to take one, too.
2. Stay indoors during traffic rush-hour periods. "Indoor air pollution levels are always much lower than outdoor, so staying inside will limit your exposure," he says. He cautioned that Beijing's definition of mild pollution would be a pollution alert day in the U.S.
3.On the plane, especially the return flight, frequently walk up and down the aisles and do leg exercises in your seat to prevent blood from pooling in your legs and clots from forming.
-- Susan Brink
Photo: Smoggy rush hour near Tiananmen Square in Beijing.
Credit: Michael Reynolds / European Pressphoto Agency