BEIJING (Reuters) - China's capital Beijing saw a small improvement in air quality last year, the city's environmental protection bureau said on Monday, although levels of a major form of pollution remain several times higher than international standards.
Beijing's average concentration of PM2.5 - particulate matter with a diameter of 2.5 microns, which can penetrate deep into the lungs - fell 6.2 percent in 2015, the bureau said in a report posted on its website.
Still, average PM2.5 levels for the year were 80.6 micrograms per cubic meter, several times higher than the World Health Organization's air quality guidelines, which call for an annual average no higher than 10 micrograms.
In the first six months of last year, Beijing's levels of PM2.5 fell by 15.5 percent compared with the same period of 2014, Greenpeace said in July.
But persistent pollution as winter neared undermined the improvements over the first half of the year.
The city issued its first ever "red alert" smog warning in December, banning heavy vehicles, restricting the number of cars on the road, advising schools to cancel classes, and requiring outdoor construction to stop.
Levels of sulfur dioxide in Beijing improved the most last year, falling 38 percent, the bureau said. Meanwhile, the number of days with heavy smog dropped by one to 46 days.
Last year, China relied on coal to provide 64 percent of its primary energy, contributing to the choking smog smothering its major cities. Planners hope next year to reduce the coal proportion to 63 percent.
(Reporting By Adam Rose; Editing by Tom Hogue)