This wasn’t the first year that smog blackened Chinese cities with appalling frequency, closed airports and roads, and sent children to hospitals with pollution-filled lungs. Though labored breathing and chronic hacking have long been a fact of life for most Chinese people, something in the awareness of the problem shifted this year—2013 will be remembered as the year that China’s struggle with air pollution went mainstream.
On the first day of the year, the Chinese government began publishing the air quality index (AQI), which measures fine particulate matter (PM2.5) per cubic meter, in real-time in 74 cities throughout the country. That made the worsening pollution quantifiable—and undeniable.
Shortly thereafter, Beijing and surrounding regions were hit by pollution of “unimaginable levels,” as The Atlantic's James Fallows put it. At one point in mid-January, AQI in Beijing soared as high as 993, far beyond levels health officials deem extremely dangerous. (Here’s the health impact based on AQI, for reference.) For comparison, on the same day in New York, the AQI was 19.