Haze and heavy rainfall caused delays and immediate destination changes to 16 flights at four southern airports Wednesday as levels of dust particles remain dangerously high in Phuket.
The haze, blown from Sumatra Island, is still raising health concerns, though in six southern provinces the threat is starting to diminish.
The levels of tiny dust particles, known as particulate matter (PM10), were declining Wednesday in Surat Thani, Satun, Songkhla, Pattani, Yala and Narathiwat, according to officials.
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Worst affected of the southern provinces is Phuket. Most air traffic disruptions occurred at Phuket airport Wednesday morning, with nine delayed landings, two planes diverted to other airports and another two forced to turn back, according to the Aeronautical Radio of Thailand (Aerothai), which said visibility was below 1,000 metres.
Among the affected airlines was a flight from Thai Lion Air from Don Mueang airport which circled above Phuket for over an hour, while a Thai AirAsia flight made a U-turn back to Don Mueang at 8.20am.
The pilots of Bangkok Airways flight PG251, which departed Koh Samui airport at 8.05am for Phuket, turned around and returned to the island at 8.30am. Pilots of Thai Silk Air Flight SLK772 from Singapore to Koh Samui decided to circle until the weather was clear. The situation returned to normal after 9.30am, according to Aerothai's regional Approach Control Service.
Foreign Ministry spokesman Sek Wannamethee said the Indonesian ambassador Lutfi Rauf has been invited to the ministry today to discuss how to solve the haze problem. The issue is also a big concern for Asean senior officials currently meeting in Malaysia, he said.
In Phuket, PM10, which are less than 10 microns in size, reached 200 microgrammes per cubic metre Wednesday afternoon, compared with the safety limit of 120 microgrammes, according to the Pollution Control Department.
The tiny particles, which are about one-seventh the width of a human hair, are considered dangerous as they can easily lodge in people's lungs.
Authorities in the seven provinces have distributed 140,000 face masks to locals, said Public Health Minister Piyasakol Sakolsatayadorn. State-run hospitals are also facing an influx of patients for treatment of respiratory-related disorders, he said.