According to the State numbers, Beijing's air pollution index is down to 156 today, which can be classified as merely "unhealthy", compared to yesterday and the day before which rated as "hazardous" with API numbers of 500 and 421 respectively.

Phew, we can breathe again.

We're down to RED ALERT today

The chart above is from Air Now, which describes itself as a "cross-agency U.S. Government Web site". The chart refers to numbers that the website calls AQI—air quality index. They appear to refer to the same thing as the term used by the authorities in Beijing: API or air pollution index.