Booking a flight? Here’s why you should always check the local air quality first

Think twice before you head off on that trip to Beijing or Kampala or Delhi: A new study from UCLA shows that even short-term trips to polluted cities have worrisome impacts on health.

Researchers followed Los Angeles residents visiting Beijing and found that concentrations of air pollutants in their bodies rose by 176% to 800% (!) a few weeks into their trips. They also found spikes in oxidized fats, which can cause heart inflammation, and a shift in enzymes that is associated with heart disease.

This, of course, raises deep concerns for locals of these cities. “It’s likely that the health effects would be even more prominent after longer exposure to air pollution, repetitive travels, or among individuals with pre-existing health conditions,” said Yan Lin, an author of the study.

Los Angeles, it turns out, previously had pollution levels comparable to modern Beijing’s, and the researchers note that environmental recovery is possible with good policies. Beijing’s concentration of airborne particles averaged 371% higher than Los Angeles’s during the study.

Air pollution is known to increase cardiovascular disease and death. This is the first study to look at short-term exposure of humans.

The good news: After returning to Los Angeles, many of the travelers’ pollutant levels returned to their pre-travel states. While we’re on the topic, here’s a dynamic Wikilist of the world’s top 500 polluted cities.