Chiang Rai: Four villages in Mae Sai district in this northern province have been affected by the foul smell caused by hydrogen cyanide (HCN) from a factory producing limes in Myanmar.
The factory, operating under the name of Ban Lom It 999, is located in the border town of Tachileik in Myanmar opposite Mae Sai. The toxic gas emitted from the site sent a foul odour adrift, upsetting about 10 nearby villages in tambon Mae Sai and Koh Chang, reports say.
Mae Sai district chief Narongphol Khid-arn has opened an emergency operation centre alerting village heads to the toxic gas in adjacent tambons. He also warned locals to wear face masks and close their windows at night.
HCN is a colourless and highly toxic gas commonly used for killing pests and gold mining. Direct exposure may cause harm to bronchi, lungs, brain, heart and blood vessels.
The pollution has affected four villages -- Muang Daeng Tai, Wiang Hom, San Sai and San Sai Mai -- in tambon Mae Sai.
A portable gas detector used by the Environmental and Pollution Control Office 1 (Chiang Mai) showed the HCN level had reached 0.5 parts per million (ppm), up from 0 ppm, which is considered harmful to the respiratory system.
On Wednesday night, the odour spread to Bang Chong in tambon Pong Pha, about 13 kilometres from the Myanmar border.
The Department of Provincial Administration and the army coordinated with Myanmar authorities via the Thai-Myanmar Township Border Committee.