Pollution levels are measured by the Air Quality Index, which goes up to 500. Or, rather, 500 is as high as the scale measures: It’s the level at which “everyone” in the city is at risk for serious health problems if they decide they need to breathe that week. On a bad day, Beijing breaks right through that ceiling. At the time we talked with our source, during Beijing’s first official smog “red alert,” he said, “Pollution levels got up to 700 … I’m not even sure how that happened … Today’s the nicest day we’ve had, and it’s 401.” That’s right – a 700 on a scale that only goes to 500. At its worst, Beijing’s air reached levels of bad that the people who measure filthy air for a living hadn’t even contemplated.
If you’re an American and are trying to compare this to anything you’ve breathed recently, don’t bother. The absolute smoggiest parts of L.A. (the most polluted city in the U.S.) hit 130 on a bad day.Most of the city hovers from 40 to 70. In other words, a “bad day” of smog in Beijing is five to 10 times as bad as the smoggiest days L.A. will ever see.