By Liz Lee
BEIJING Runners undeterred by thick smog engulfing the Chinese capital ran the Beijing Marathon maskless on Sunday, many wearing shorts in one of the warmest Octobers on record.
Despite a greyish brown smog settling, some 30,000 marathoners set off at 7:30 a.m. (2330 GMT) from Tiananmen Square on the route through four districts of the Chinese capital over 42.195 km (26.2 miles).
Beijing was the fourth most-polluted major city in the world on Sunday, according to Swiss air-quality technology firm IQAir.
In the Haidian district on Beijing's outskirts, the sky looked dreary, but hikers and visitors showed up at the Fragrant Hills Park where many go to enjoy autumn foliage, according to a Reuters witness.
China's national forecaster advised the public to wear masks, warning on Sunday morning of low visibility in the capital and neighbouring regions, with air quality reaching moderate or severe pollution.
Steel production hubs in Tangshan, Handan and other cities in the northern province of Hebei launched emergency responses on Friday after heavy air pollution forecasts. The notices did not indicate when the controls would be lifted.
The smog adds unusually warm October weather, due to significantly weaker cold air currents from the north as the polar vortex that sends cold air southward was situated further north recently, experts said.
Beijing's high on Sunday was 19 C (66 F), according to the national weather bureau.
Parts of China, including in the north and northeast, have been experiencing temperatures 2 to 4 degrees Celsius (4-7 Fahrenheit) higher than normal the past 10 days.
"At present, a total of 237 national meteorological stations have broken historically highest temperatures in late October, which is still a relatively rare situation," National Meteorological Centre chief forecaster Fang Chong was quoted by state media as saying.
The weather bureau forecast weak cold air currents to last the rest of the month before beginning to cool in early November.
(Reporting by Liz Lee and Ryan Woo; Additional reporting by Han Xiao and Bernard Orr; Editing by William Mallard)