The level of particulate matter 2.5 microns in diameter in the air ranged from 52 to 57 micrograms (mcg) per cubic metre, higher than the acceptable limit, the department said.
Residents have been advised to take care of their health and wear masks.
Districts having PM2.5 levels above safe levels are:
1. Thawi Watthana
2. Nong Khaem
3. Bangna
4. Pathumwan
5. Prawet
6. Yannawa
7. Bang Khen
8. Khlong Sam Wa
9. Thonburi
10. Bang Khun Thian
11. Khlong San
The overall air quality level in 50 districts across Bangkok were found to be in the range of 28 to 57mcg per cubic metre, while the safety level over a 24-hour period should not to be more than 50mcg per cubic metre.
Cool weather and morning fog are forecast for Greater Bangkok with a 1-2 degrees Celsius rise in temperature as the moderate high-pressure system covering upper Thailand has weakened, according to the Environment Department.
The air quality in Bangkok should be monitored from December 23 evening when the weather is expected to be calm and windless, the department said.