BANGKOK, THAILAND – Thailand launched a 90-day special operation against heavily polluting diesel vehicles in a bid to tackle deadly fine dust in the capital.
Smog emergency and diesel cars in focus
The air in Bangkok was described as thick again, with a toxic mix turning the city into a smog dome from November to March and millions of diesel vehicles blamed. Police Lieutenant General Ittiporn Pho Thong, adviser to the deputy prime minister, announced the campaign and said diesel engines were a major source of PM2.5 in the capital.
“More than 3 million diesel vehicles are responsible for 57% of the PM2.5 in Bangkok,”
said Ittiporn Pho Thong, adviser to the deputy prime minister.
The capital had been officially declared an air quality control zone, triggering stricter measures that placed the health of residents as the top priority.
Tighter emission limits and widespread inspections
Regulations were significantly tightened, with the permitted soot level in exhaust tests cut from 30% to a maximum of 20%, effective from 1 November 2025. Inspections now took place at bus depots, concrete mixer trucks, construction sites and along busy roads, carried out by a wide network of agencies.
Authorities stressed that vehicles exceeding the limits would be taken off the road, signalling there was no escape for environmental offenders.
High-risk period and daily checkpoints
The so‑called danger period ran from 1 December 2025 to 28 February 2026, during which enforcement was intensified for 90 days. Each day, 14 checkpoints were operated in Bangkok and 16 checkpoints in surrounding provinces, while other large Thai cities followed suit.
The checks were a joint effort by the police, the transport authority, the environmental office and local administrations, with the cooperation aimed at closing enforcement gaps.
Shorter repair deadlines and higher fines
Owners of vehicles found in violation had to act quickly, as the deadline for repairs was shortened from 30 days to just 15 days. Missing this deadline exposed them to fines of up to 5,000 baht (about 125 euros), in addition to possible penalties under the Vehicle Registration Act and Land Transport Act.
“Vehicles that are not repaired will continue to be subject to fines,”
said Surin Worakijthamrong, director of the environmental protection agency.
Between October and November, 85,731 vehicles had already been inspected.
Support for car owners through incentives
The government also offered assistance through the “Green List Plus” programme to actively support vehicle owners. Car owners could have their vehicles checked free of charge at partner garages and received 50% discounts on engine checks, oil changes, spare parts and labour.
Additional incentives included free parking in shopping centres, BTS vouchers and insurance discounts, forming a package of benefits designed to make compliance more attractive.
Early results show limited improvement
Initial figures from the first two months were sobering: of more than 62,000 vehicles inspected in Bangkok, 656 exceeded the emission limits. Only 291 vehicles (44%) were successfully repaired and passed the follow‑up test, leaving the remainder facing consequences under the tightened rules.
The 90‑day offensive was seen as a test of the government’s determination, with its success likely to be judged by whether the black plumes of exhaust on Bangkok’s streets actually diminished.