The department said all measured air quality indicators around the airport were within permitted limits, with total suspended particulate (TSP) concentrations averaging about 82.9 µg/Nm3 across the monitoring periods.
During the first monitoring round of 2026, dust levels at two locations around the airport slightly exceeded permitted limits, averaging about 135.6 µg/Nm3.
No exceedances were recorded in the second and third rounds, when dust levels ranged from just over 30 to 132 µg/Nm3 and averaged about 69.5 µg/Nm3 and 43.6 µg/Nm3, respectively.
The improvement was attributed to construction projects around the airport nearing completion, reducing dust released into the surrounding air.
Dong Nai monitored air quality at 217 locations in each round, including 184 sites with periodic monitoring, 28 sites monitored for 24 hours using mobile automatic equipment and five automatic air-monitoring stations.
Across Dong Nai, air quality remained relatively good during the first three monitoring rounds, with sulphur dioxide, nitrogen dioxide, carbon monoxide, hydrogen sulphide and ammonia all within permitted limits.
However, TSP and PM10 dust and noise exceeded permitted levels at some locations, mainly due to heavy traffic, trucks carrying construction materials and weather conditions.
At 29 industrial parks covering 60 monitoring locations, sulphur dioxide, nitrogen dioxide and carbon monoxide remained within permitted limits, although dust and noise occasionally exceeded standards.
Air quality was also generally good at 21 urban residential monitoring sites in southern Dong Nai, though PM10 exceeded permitted levels in Trang Dai Ward in all three rounds.
At 16 traffic monitoring sites, poor air quality accounted for 15 per cent of monitoring hours in the third round, while very poor air quality accounted for 1 per cent.
The department called for tighter traffic controls, more road cleaning and stronger monitoring of facilities generating dust and emissions.