PUBLISHED : 19 Dec 2023 at 04:00
Rainmaking efforts that were carried out east of Bangkok have led to a dramatic drop in pollution across the capital and its surrounding areas, with levels of harmful, ultra-fine pollutants in the atmosphere reported to have dropped back below the safe threshold yesterday.
The director-general of the Department of Rainmaking and Agricultural Aviation, Supis Pitakham, said cloud-seeding operations were carried out between Dec 16-18 east of Bangkok after a spike in PM2.5 levels was observed across the city last week.
Mr Supis said that two Cessna Caravan aircraft on Saturday took part in two successful cloud-seeding operations over Ban Bung district in Chon Buri and Khong Khuan district in Chachoengsao, which caused PM2.5 levels to drop in the area.
The planes took part in two more rounds of cloud-seeding on Sunday, this time above Phanom Sarakham in Chachoengsao and Pak Phli district in Nakhon Nayok.
Light rain was observed in Ongkharak district in Nakhon Nayok and Nong Sua district in Pathum Thani following the operation, he said.
Because of the rainmaking efforts in those areas, the air quality in Bangkok and its surrounding provinces improved significantly, with PM2.5 levels in the city reported to be below the safe threshold for exposure as of yesterday morning.
He said rainmaking operations around Bangkok and its surrounding provinces must be carefully planned to ensure success.
If the wind is blowing from the east, the operation must be carried out over Rayong, but if the wind is coming from the west, it must be carried out over Kanchanaburi.
Rainmaking efforts must also take place at least 70 nautical miles (129 kilometres) from Suvarnabhumi and Don Mueang airports to meet international aviation rules, he said.