Environment (Protection) Amendment Rules, 2023 – Revised emission standards for Boilers

The Ministry of Environment, Forest & Climate Change has released Environment (Protection) Amendment Rules 2023. These new rules are for the revision of emission standards of particulate matter (PM) for industrial boilers. In the Environment (Protection) Rules, 1986, in Schedule-l,- (a) for serial number 70 in which these standards are mentioned is substituted by the new standards for the industrial boiler as per the below table.

Boilers (Steam generation capacity, ton/hour)

Type of industrial boiler (fuel-wise) and Standards

Agro-based fuels/bagasse

Other fuels

Less than 2    

500 mg/Nm3

500 mg/Nm3

2 to less than 10

250 mg/Nm3

150 mg/Nm3

10 and above

250 mg/Nm3

100 mg/Nm3


  • Minimum stack height (in meter) shall be as per the formula, namely:- H=14Q0.3 (where Q is SO2 emission rate in kg/hr); or H=74Q0.27 (where Q is PM emission rate in tonne/hr), whichever is more. However, in no case the stack height shall be less than 11 m for boilers of < 2 ton/hour steam generation capacity and 30 m for boilers of higher steam generation capacity.
  • Measured values of PM, SO2 and NOx to be normalised at 6% O2 for solid fuels and at 3% O2 for liquid fuels, on dry basis, for comparing with above standards, as below, namely:- Normalized value = Measured value × [ (21- Ref O2 at 6 or 3 %) / (21 – measured O2 in %)]
  • These standards are for industrial boilers using coal or lignite, pet coke, bagasse or agro-fuels, and Furnace Oil or Light Diesel Oil or Low Sulphur Heavy Stock, boilers of bagasse or agro-fuels based power plants, and also for Thermic Fluid Heater (TFH) and Hot Air Generator (HAG) on equivalent fuel consumption basis. Whereas, for boilers of coal or lignite based power plants the emission standards notified for thermal power plants, vide notification no S.O. 3305 (E), dated 7th December, 2015 shall be applicable”.

For more detailed rules, Click on below given link.

Download – Environment (Protection) Amendment Rules, 2023 – Revised emission standards for Boilers

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