Bangkok is Asia's 13th most-polluted city

BANGKOK - Bangkok ranks 13th in Asia when it comes to air pollution in the form of carcinogenic polycyclic aromatic hydrocarbons (PAHs), according to research revealed yesterday.

"On average, the amount of PAHs in Bangkok is 2.2 times higher than the safe limit," said Associate Professor Siwat Pongpiajun, head of the NIDA Centre for Research and Development of Disaster Prevention and Management.

NIDA's study analysed the cancer risks from PAHs in samples collected from seven air-quality monitoring stations in Bangkok from 2006 to 2009.

The safe limits require that PAHs stand at no more than 250 picograms per cubic metre of air.

"But on average, the amount is 554 picograms in Bangkok," Siwat said.

The highest PAH readings were from the Keha Chumchon Din Daeng monitoring station.

"It is as high as 990 picograms," Siwat said.

People facing the highest risks from PAHs were those living by the roadside.

According to Siwat, residents in Beijing face even higher cancer risks from PAHs, with readings as high as 24,600 picograms per one cubic metre of air. "That is 98 times higher than the safe limit," he said.