EXPLAINER: How China got blue skies in time for Olympics

The ensuing efforts were similar to the measures China had previously taken to ensure clear skies for the 2008 Summer Games in Beijing, but on a larger scale, the report notes. Tougher emissions standards were imposed on coal-fired plants and the number of cars on the road was curbed to cut vehicle emissions. Local officials were given environmental targets, and coal-fired boilers in homes were replaced with gas or electric heaters.

The government’s reporting of air quality data also improved.

Jia Pei, a 30-year-old Beijing resident who enjoys exercising outside, said the improved air quality puts him in a better mood.

“In the past when there was smog, I would feel that I was inhaling dust into my mouth,” he said.

IS BEIJING’S AIR CLEAN NOW?

Despite the progress, Beijing’s annual average air pollution last year was still more than six times the limit laid out by the World Health Organization’s guidelines.

And the concentration of coal-burning industries that still surrounds the city means it remains susceptible to bad air days, said Lauri Myllyvirta at the Center for Research on Energy and Clean Air in Helsinki, Finland.

When those happen can depend on factors like car traffic or how much wind there is to blow away smog.