Environment (Protection) Fourth Amendment Rules, 2025: SO₂ Standards Updated for Thermal Power Plants

Introduction: Regulatory Flexibility Meets Environmental Accountability

In response to technological limitations, economic feasibility, and stakeholder feedback, the Ministry of Environment, Forest and Climate Change has amended the Environment (Protection) Rules, 1986. The latest update—Environment (Protection) Fourth Amendment Rules, 2025—was notified on 11 July 2025. This amendment significantly revises the compliance timelines for Sulphur Dioxide (SO₂) emission standards for coal and lignite-based thermal power plants.

The updated Environment Protection Rules Amendment reflects a practical approach to air quality regulation, balancing pollution control goals with ground-level challenges faced by the power sector. This blog unpacks the amendment in detail.

Why the Amendment Was Needed

Over the years, multiple stakeholders had requested timeline extensions due to:

Limited availability of tech providers
High implementation costs
COVID-19–induced supply chain disruptions
Low ambient SO₂ levels in many regions
Consumer price concerns due to higher power tariffs

Based on these challenges and studies from research institutions, the Ministry of Power, CPCB, and other experts recommended timeline relaxations. Thus, the Environment Protection Rules Amendment was introduced with a broader consultative approach.

Revised Compliance Categories: A, B & C

A Task Force formed by CPCB has reclassified thermal power plants into three categories based on location:

Category	Location
A	Within 10 km of NCR or million+ cities
B	Within 10 km of Critically Polluted Areas or non-attainment cities
C	All others not in A or B

This categorization tailors compliance timelines to environmental sensitivity.

Updated Timelines for Parameters (Except SO₂)

Category	Compliance Deadline	Retirement Exemption Cut-off
A	31 Dec 2022	31 Dec 2022
B	31 Dec 2023	31 Dec 2025
C	31 Dec 2024	31 Dec 2025

Plants that commit to retiring before these dates can seek SO₂ compliance exemption. However, they must file an undertaking with CPCB and CEA.

Sulphur Dioxide Emission Standards: What’s New

Category A Plants:
- Must comply with SO₂ norms by 31 December 2027
- Units commissioned after this must comply before operation
Category B Plants:
- Case-by-case evaluation via Expert Appraisal Committees
- Plants with prior EC may apply for a review within 6 months
- If applicable, SO₂ norms become mandatory by 31 December 2028
- Otherwise, stack height norms (GSR 742E/1990) apply
Category C Plants:
- SO₂ standards not applicable
- Must comply with stack height norms by 31 December 2029
All other plants not opting for review must comply by 31 December 2028

The Environment Protection Rules Amendment gives flexibility but imposes clear deadlines.

Environment Compensation for Non-Compliance

For plants that continue operations without compliance:

Delay Period	Penalty (₹ per unit electricity)
0–180 days	0.20
181–365 days	0.30
>365 days	0.40

This financial penalty discourages extended non-compliance and supports environmental recovery.

Exemptions Based on Retirement Plans

Units declaring retirement before 31 December 2030 may skip SO₂ compliance.
If they continue beyond the date, they will be fined ₹0.40 per unit.

Stack Height Requirement Still Mandatory

Where SO₂ norms are not enforced, plants must follow stack height standards under GSR 742(E), 1990 to ensure proper pollutant dispersion.

What This Means for Power Producers

Projects must review their current status under Categories A, B, or C.
All EC holders under Category B should apply for review via PARIVESH portal within 6 months.
Future plants must comply before starting operations.
Non-compliance will now attract heavy penalties, both financial and reputational.

The Environment Protection Rules Amendment demands strategic planning, early compliance, and increased environmental responsibility.

Conclusion: A Pragmatic Policy Update

The Environment (Protection) Fourth Amendment Rules, 2025 reflect India’s shift toward smarter environmental governance. By introducing differentiated timelines and case-wise reviews, the Environment Protection Rules Amendment balances economic challenges with ecological responsibility. Stakeholders now have a structured path toward compliance, with enough room for adaptation—yet backed by firm accountability mechanisms.

As the country moves toward a cleaner power grid, these timely amendments will help achieve emission goals without compromising energy security.

Download: Environment Rules Fourth Amendment Extends SO₂ Compliance