Data shows that levels of nitrogen dioxide (NO2) — a noxious gas resulting from fossil fuel combustion — dropped by nearly 50% and levels of carbon monoxide (CO) fell by 20%. The fall could be attributed directly to Olympic restrictions, said Jacquelyn Witte, a NASA atmospheric scientist. "After the authorities lifted the traffic restrictions, the levels of these pollutants shot right back up," she added.
Sulphur dioxide (SO2) — a byproduct of coal-fired power stations — also registered a decline. But due to the relatively long lifetime of the gas in the atmosphere and efforts by Chinese authorities to reduce SO2 emissions across the country, scientists say that levels were more difficult to monitor in relation to Olympic regulations.
During the 2008 Olympic Games, Chinese authorities introduced numerous restrictions to help clear the Beijing air, including limits on the number of days drivers were allowed to use their cars and forced factory closures. Officials recently decided to continue less stringent versions of the Olympic driving restrictions, Xinhua News Agency reported.
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