Sniffing for excessive exhaust emissions were officials from the Traffic Police Division, Pollution Control Department (PCD) and Don Mueang District Office. They spent about two hours flagging down truckers close to Don Mueang Airport.
Twelve of the 25 trucks checked were found to be belching black smoke containing pollutants in excess of safety standards.
PCD environmental specialist Thawatchai Kaewpakdee said the department was empowered under Sections 55 and 56 of Vehicle Act to order the drivers of the 12 trucks to keep them off the road while the necessary engine improvements are made, and that has to be done within 30 days.
Operators of trucks that miss the deadline can be fined up to Bt5,000.