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Air-quality tests conducted over the past two days showed

the average amount of dust particles smaller than 10

microns stood at 149 micrograms per cubic metre in

Bangkok's Din Daeng district and 120 micrograms per cubic

metre in Bang Khunthien. The department requires

that small dust particles be no more than 120 micrograms per

cubic metre, or air is rated as unsafe.

"The dust particles also exceeded the acceptable limit in

Saraburi, Samut Prakan, Ayutthaya, Ratchaburi and Samut Sakhon," Supat said.

The tests found the average amount of dust particles

small?er than 10 microns was as high as 280 micrograms per

cubic metre in Saraburi, 168 micrograms in Samut Prakan,

144 micrograms in Ayutthaya, 127 micrograms in Ratchaburi,

and 123 micrograms in Samut Sakhon.

Supat said there were also many times last year when the

amount of ozone rose higher than the accepted limit.

"Such incidences were recorded in Saraburi, Rayong,

Chiang Mai, Chon Buri, Ratchaburi, Pathum Thani,

Nonthaburi, Samut Sakhon and Bangkok," he said.

Supat said ozone came from volatile organic compounds,

which were generated by petrol stations, metal-coating

facto?ries, plants where electronic items were made, and

restau?rants where food was grilled.

Janjira Pongrai

The Nation