ON January 12th of last year, in an article in the print edition of The Economist, we reported that the public outcry over Beijing’s atrocious air quality was putting pressure on officials to release more data about more kinds of pollutants. We also noted that Chinese authorities had already embarked on a wide range of strategies to improve air quality, and that they probably deserve more credit than either foreign or domestic critics tend to give them. But we concluded with the sad reality that such work takes decades, and that “Beijing residents will need to wait before seeing improvements.”
On January 12th of this year, Beijing residents got an acrid taste of what that wait might be like, as they suffered a day of astonishingly bad air. Pollution readings went, quite literally, off the charts. Saturday evening saw a reading of 755 on the Air Quality Index (AQI). That index is based on the recently revised standards of the American Environmental Protection Agency (the EPA), which nominally maxes out at 500. For more perspective, consider that any reading above 100 is deemed “unhealthy for sensitive groups” and that anything above 400 is rated “hazardous” for all.
Like many Beijing residents, your correspondent has mobile-phone apps that keep up with the pollution readings. At an otherwise pleasant Saturday-evening meal with friends, he joined his companions in compulsively checking for updates.
Those previously unseen numbers were hard to believe, but they did seem to match up well enough with the noxious soup we could see, smell and taste outside. We are all far more familiar with the specifics of air-quality measurement than we would like to be. Apart from the AQI readings above 700, we were quite struck to see the readings for the smallest and most dangerous sort of particulate matter, called PM 2.5, which can enter deep into the respiratory system. These are named for the size, in microns, of the particles. A reading at a controversial monitoring station run by the American embassy showed a PM 2.5 level of 886 micrograms per cubic metre; Beijing’s own municipal monitoring centre acknowledged readings in excess of 700 micrograms.