Guangzhou and neighbouring cities, having pulled out all the stops to clean up the air and water in the Pearl River Delta, say the environment is ready for the Asian Games - if the heavens play their part.
They have had less of a headache than Beijing before the 2008 Olympic Games, because air pollution is less severe in the delta.
At the centre of the manufacturing hub, Guangzhou is surrounded by tens of thousands of factories, which are the main polluters in the region. And as one of the mainland's primary car manufacturing bases and one of the country's wealthiest cities, Guangzhou sees several hundred new cars hit the streets every day. They, like the factories, pump large amounts of particulate matter less than 10 microns in diameter (PM10) into the city's air.
But environmental protection experts say Guangzhou, a coastal city, has more breezes from both the sea and inland that can blow away the kind of smog that plagued Beijing.
Levels of PM10, which is created mainly through the burning of fossil fuels, such as petrol in vehicles, and is regarded as a major threat to athletes' health, averaged 66 micrograms per cubic metre in Guangzhou last year, a little higher than the WHO air quality guideline level of 50 micrograms, and much lower than the 98 micrograms recorded in Beijing in late July 2008, a month before the Olympics opened.
Guangdong's environmental protection watchdog says PM10 levels have dropped nearly 30 per cent in the past six years, with all nine cities in the region - Guangzhou, Foshan , Dongguan , Zhongshan , Zhuhai , Shenzhen, Huizhou , Jiangmen and Zhaoqing - working together to reduce them.
Environmental protection experts agree, attributing the improvement in PM10 levels to measures taken by local authorities since 2004, when Guangzhou won the right to host the Games.
Heavy polluters, such as power plants, were asked to cut their emissions of sulphur dioxide and nitrogen oxide, and tougher, European emissions standards were introduced for vehicles. Official figures show more than 5,000 polluters, including factories and construction projects, have been shut down since 2007. Many were fined for violating environmental protection regulations.
The Guangzhou Environmental Protection Bureau reported late last month that fines collected in 2008 exceeded the total in the previous three decades. But smog, which recurs each winter and spring, is still considered the biggest potential threat to Guangzhou's air quality during the Games.
Chen Guangrong , deputy chief of the Guangdong Environmental Protection Department, told a news conference late last month the watchdogs had done their jobs, and the rest was up to the heavens.
A report by the Guangzhou Environmental Monitoring Centre shows that the city was plagued by severe smog between November 23 and 28 last year, with average PM10 levels of 200 micrograms per cubic metre.
Fan Shaojia , an atmospheric expert at Sun Yat-sen University, said smog was generally caused by the slow air flow in the delta between September and March.
'The pollutants in the air will hang over the region if there is no typhoon from the sea and no cold wind from the north,' Fan said. Without strong wind to disperse pollutants, there is little that can be done to tackle smog apart from restricting car use or temporarily shutting down factories.
Yang Liu , deputy chief of the Guangzhou Environmental Protection Bureau, said that according to the emergency plan it had drafted for 'extreme weather conditions' in the next two months, up to 113 enterprises in the city would be shut down for three to five days.
Fan and other air pollution experts have backed the suggestion.
'The cause of smog is various,' Fan said. 'And more important, no matter whether we want to shut down the industrial enterprises or ban more vehicles from the streets, we must do that a few days in advance, otherwise it'll be useless.'
If there was little wind to disperse the pollutants, he suggested that the 'emergency plan' should be also launched in Guangzhou's neighbouring cities.
Neither officials nor experts can tell now whether the six-year fight against air pollution for a green Asian Games will work. But senior officials with the provincial and city environmental protection departments said they did not want to have to launch the 'emergency plan.'
'The heavens will be the most important factor at that time,' Fan said.
'As people we make an effort and hope it helps.'