Bhutan releases Environmental Standards, 2020, establishing various standard values 
In June 2020, the National Environment Commission of Bhutan released the Environmental Standards, 2020. The standards establish standard values for the following 11 criteria.
- Ambient water quality criteria
- Industrial effluent discharge standards
- Sewage treatment plant discharge standards
- Ambient air quality criteria
- Industrial emission standards (maximum limit for pollutants)
- Industrial emission standards (aluminum smelting)
- Workplace emission standards
- Vehicular emission and noise limit standards (details are listed in the table below)
- Noise level limits
- Incineration emission standards
- Waste incinerator ash disposal/utilization standards
The original text of the Environmental Standards, 2020 can be downloaded from the following URL.
http://www.nec.gov.bt/publications/download/environment-standards-2020
Vehicular emission standards
| Fuel type | Vehicles registered prior to January 2005 | Vehicles registered after January 2005 | Vehicles registered prior to January 2021 | Vehicles registered after January 2021 (approval type: Euro 6/BS VI) |
| Petrol/Gasoline (%CO) | 4.5% | 4.0% | 4.0% | 0.5% |
| Diesel (%HSU) | 75% | 70% | 70% | 50% |
Vehicular noise limit standards
| No. | Type of vehicle | Noise limits dB(A) |
| Two-wheelers | ||
| 1.1 | Displacement up to 80 cc | 75 |
| 1.2 | Displacement more than 80 cc but up to 175 cc | 77 |
| 1.3 | Displacement more than 175 cc | 80 |
| 2 | Vehicles used for carriage of passengers and capable of having not more than 9 seats, including the driver’s seat | 74 |
| Vehicles used for carriage of passengers having more than 9 seats, including the driver’s seat, and a maximum Gross Vehicle Weight (GVW) of more than 3.5 tons | ||
| 3.1 | With an engine power less than 150 kW | 78 |
| 3.2 | With an engine power of 150 kW or above | 80 |
| Vehicles used for carriage of passengers having more than 9 seats, including the driver’s seat
Vehicles used for carriage of goods |
||
| 4.1 | With maximum GVW not exceeding 2 tons | 76 |
| 4.2 | With maximum GVW greater than 3 tons but not exceeding 3.5 tons | 77 |
| Vehicles used for transport of goods with a maximum GVW exceeding 3.5 tons | ||
| 5.1 | With an engine power less than 75 kW | 77 |
| 5.2 | With an engine power of 75 kW or above but less than 150 kW | 78 |
