All gas stations in Beijing will be retrofitted to prevent petroleum vaporization from causing smog and help improve air quality before the 2008 Games, an Olympics environmental advisor has said.

Sarah Liao Sau-tung said the municipal government has started equipping about 1,400 gas stations with vapor traps and recovery devices on which work is expected to be completed by the end of next May.

Also, 1,245 oil tank vehicles and 37 fuel storage areas will be covered. In addition to improving air quality, the efforts can help recover 20,000 tons of gasoline per year and decrease safety hazards at filling stations.

Photochemical smog, which Beijing often suffers from, forms when photons of sunlight hit molecules of different kinds of pollutants in the atmosphere, creating an atmospheric condition that produces eye irritation and poor visibility. It smells bad and makes it hard for people to breathe.

The vaporization of volatile organic compounds (VOCs) from fueling, storage and transportation acts as a catalyst for smog formation.

The surrounding mountain ranges that block air circulation also help the formation of such smog in Beijing.

Sources close to the State Environment Protection Administration (SEPA) said the neighboring Hebei Province and Tianjin Municipality have also decided to join the cleaning drive. Beijing, Tianjin and Hebei together cover about 200,000 sq km, a size close to that of the UK.

"It's a huge undertaking and I am confident the measures can help mitigate the occurrence of photochemical smog," Liao, former secretary for the environment, transport and works of Hong Kong, told China Daily.

(China Daily December 7, 2007)