Rainmaking mission extended as Bangkok air quality improves slightly

With support from 10 aircraft, the rainmaking department has broken the atmospheric inversion layer, making dispersal of fine dust easy

The Department of Royal Rainmaking and Agricultural Aviation has adjusted its flight schedule to enhance the dispersion of fine dust in the air after PM2.5 readings have started showing some improvement.  

Rachen Silparaya, the department’s deputy director-general, said that PM2.5 pollution in Bangkok and its vicinity on Monday was at the moderate or “yellow” level. This improvement was attributed to a strong high-pressure system from China, which is affecting upper Thailand and bringing strong winds to Bangkok and its vicinity. 

Additionally, the department’s operations have successfully broken the atmospheric inversion layer, further aiding the dispersal of dust particles. An atmospheric inversion layer is when warm air sits above a layer of cooler air, essentially trapping pollutants near the ground and leading to poor air quality conditions.  

Around mid-February, the seasonal shift in wind direction is expected to gradually improve air quality in Bangkok, though this may worsen PM2.5 levels in the North of Thailand. 

The department has been closely monitoring the fine dust levels since last month, as this problem typically arises between December and April every year. To mitigate PM2.5, operations commenced early this season, with Bo Fai Airport in Prachuap Khiri Khan’s resort town of Hua Hin serving as the central hub. Five aircraft are stationed there, with additional support from three aircraft in Kanchanaburi and two in Rayong. 

Before each operation, the team conducts planning meetings and compares air quality index (AQI) readings taken at 8am with readings after operations at 11am and again before 2pm and after the 5pm operation. Readings reportedly show consistent air quality improvements after the operations. 

The department is now planning to extend flight operations to the early morning (2 to 5am), as AQI levels typically peak between midnight and 2am. Approval for these extended operations is being sought from the Aeronautical Radio of Thailand.

Rachen said that the department's operations can help resolve the issue to some extent while stopping burning is the most effective solution.

(2025/01/27-00:00)