Emission Standards (air emission standards)

Emission standards are the numerical limits — expressed mostly in mg/Nm³ for stack concentration, and sometimes as a mass-load cap — that a facility's air emissions must not exceed. In India they come in two layers: General Standards applicable to all sources (for example particulate matter, SO₂, NOₓ) and industry-specific standards notified for sectors such as cement, iron and steel, thermal power and waste incineration. They are issued by the CPCB under the Environment (Protection) Rules 1986 and made enforceable through each unit's Consent to Operate granted by the State Pollution Control Board.

Standards are nearly always defined at normal conditions (dry gas, 0°C, 1 atmosphere) and frequently corrected to a reference oxygen percentage (commonly 11% O₂ for incineration, 12% CO₂ for some combustion sources). This correction stops operators from diluting flue gas with extra air to fake compliance — the board recalculates the measured value back to the reference basis. A reading that looks compliant on raw gas can fail after correction.

For thermal recyclers the binding standards include particulate matter (typically 50-150 mg/Nm³ depending on source), SO₂, NOₓ, HCl, HF, and for any process burning chlorinated material the dioxins and furans limit of 0.1 ng TEQ/Nm³ that applies to waste incineration and co-processing. Plastic and tyre pyrolysis units are increasingly held to incineration-grade emission standards by SPCBs because of the dioxin and acid-gas risk.

The practical approach is to design control equipment to meet the relevant standard with margin, not to the limit exactly — flue gas conditions vary with feedstock moisture and load. Document the applicable standard (general or industry-specific) in your consent application, size the scrubber/baghouse accordingly, and budget for periodic NABL-accredited stack testing (Rs 8,000-25,000 per stack per campaign) as the evidence the board accepts.