Table 4 Permissible limits of major pollutants from boiler operations in various industries (as per Indian Standards).

1.

Particulate Matter (PM)

Coal-based thermal power plants:

(a) Units with capacity < 500 megawatts (MW): 50–150 mg/Nm³

(b) Units with capacity ≥ 500 MW: 30–100 mg/Nm³

2.

Sulfur Dioxide (SO₂)

100–2000 mg/Nm³ for coal-fired boilers in various industries, depending on boiler capacity and fuel type

3.

Nitrogen Oxides (NO_x)

Thermal power plants:

(a) Units with capacity < 500 MW: 300–600 mg/Nm³

(b) Units with capacity ≥ 500 MW: 200–300 mg/Nm³

4.

Carbon Monoxide (CO)

Industrial boilers: 1000–2000 mg/Nm³