BEIJING Haze settled over Beijing on Wednesday, two days before the start of the Olympic Games that have been beset by worries over pollution, but experts were predicting clear skies for the opening ceremony.
Compounding weather worries, Hong Kong, where equestrian events are scheduled to start on Saturday, raised a warning for an approaching tropical storm.
Tropical storms often develop over the South China Sea in the summer months, growing into full-fledged typhoons threatening China, the Philippines, Taiwan, South Korea and Japan.
"Severe" Tropical Storm Kammuri was centred about 130 km (80 miles) south-southwest of Hong Kong and was forecast to move west-northwest.
That could mean welcome rain later in Beijing, but possible troubles in Hong Kong, where competitors had discussed the possibility of a delays in the competition due to the weather.
Cloudy skies were forecast for Wednesday and Thursday in Beijing where the Environmental Protection Bureau showed that levels of particulate matter were within the "fairly good" range.
But humid, still weather and the temperature hitting 34 degrees Celsius (93 Fahrenheit) meant stubborn smog hung over the city, which has already pulled millions of cars off the roads and halted factory production to ensure a better Games environment. Chronic pollution has been one of the biggest worries for Games organisers who have had to deflect international criticism over air quality.
For athletes of endurance events, the smog could pose a major problem and the International Olympic Committee has said it might reschedule events if the pollution is too bad.
But a researcher at the Chinese Academy of Sciences predicted Beijing's air quality would stay in the "fairly good" range for the opening ceremony on Friday, Xinhua news agency reported.
"I think the city's comprehensive and strict measures to control pollution have paid off," Xinhua quoted Wang Zifa, with the Academy's Institute of Atmospheric Science, as saying.
Beijing's Meteorological Bureau was forecasting overcast weather, but Wang predicted rain, which could clear the haze and brighten prospects for blue skies on Friday.
But the metropolis of 15 million will also see winds from the south in the next few days, Xinhua quoted environmental experts as saying, meaning pollution from neighbouring provinces could waft into the city.
Although officials have a back-up plan to take more cars off the road in Beijing and nearby Tianjin and close additional factories in the surrounding province of Hebei, they are holding off in the hope the weather will clear by itself.
"We haven't been told to implement any additional measures," Li Jianguo, deputy director of the Beijing Municipal Bureau of Communications, told Reuters.
The problem of pollution in outlying areas underscores the complicated challenge the city faces in trying to contain the environmental effects of decades of breakneck economic growth.
(Additional reporting by Jim Bai; Editing by Nick Macfie)