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

“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.

Read more: The Nation