CPCB OCEMS Lawyer

Environmental matters move on paperwork and deadlines. This page sets out how air pollution, stack and fugitive emissions, OCEMS and DG sets works in practice where the CPCB is involved. Legals365 is the legal platform of Advocate B.K. Singh and associates, who appear before pollution control boards, the NGT and the courts.

In short. Air pollution cases against industry arise under the Air (Prevention and Control of Pollution) Act 1981 and the Environment (Protection) Act 1986: emissions above consent limits, uncontrolled fugitive dust, OCEMS exceedances or data gaps, and non-compliant DG sets. Boards can issue show cause notices, closure directions under section 31A, environmental compensation and penalties. In NCR, CAQM directions and GRAP restrictions apply on top.

Most air pollution trouble for a business starts with a notice: a show cause notice from the state pollution control board after an inspection, an automated alert because the online monitor on a stack crossed a limit, a CPCB flying squad report on dust around a crusher, or a CAQM order in NCR about a diesel generator. Ignored, these notices turn into closure directions, disconnection of electricity and water, environmental compensation running into lakhs, and in serious cases proceedings before the National Green Tribunal or the Supreme Court.

This page covers the air side of environmental law for industries, commercial buildings, hospitals, hotels and housing societies: the consent regime, stack and fugitive emission standards, online continuous emission monitoring (OCEMS), diesel generator sets, NCR-specific rules under the Commission for Air Quality Management, how notices are answered and challenged, and what affected residents can do. It is written for both sides: the unit that has received a notice, and the people living next to it.

Law

Air (Prevention and Control of Pollution) Act 1981 (sections 21, 22, 26, 31, 31A, 37); Environment (Protection) Act 1986 and Environment (Protection) Rules 1986 (industry standards, DG set norms, rule 4 notice); Commission for Air Quality Management in NCR and Adjoining Areas Act 2021; National Green Tribunal Act 2010; Jan Vishwas (Amendment of Provisions) Act 2023.

Regulators

State pollution control boards (DPCC in Delhi, UPPCB, HSPCB and others), CPCB, the Commission for Air Quality Management in NCR, MoEFCC, and district authorities enforcing GRAP.

Forum

Appellate authority under section 31 of the Air Act, then the National Green Tribunal; NGT directly for original applications and appeals under the NGT Act; High Court in writ; Supreme Court in the Delhi air pollution matters it supervises.

Time limit

Appeal against a board order to the appellate authority within 30 days; NGT appeal under section 16 within 30 days, extendable by 60 days; NGT original application under section 14 within 6 months of the cause of action, extendable by 60 days. Replies to show cause notices within the time stated, often 7 to 15 days.

Documents

Consent to establish and consent to operate with conditions, stack monitoring reports from a recognised laboratory, OCEMS data and calibration records, APCD maintenance logs, DG set type approval and noise certificates, inspection report and the notice, photographs, fuel records.

The law on industrial air pollution

The consent order is where most cases start

The consent to establish (CTE) and consent to operate (CTO) issued by the state board are the documents against which almost every air pollution notice is tested. They fix the number and height of stacks, the emission limits for particulate matter, sulphur dioxide, oxides of nitrogen and other pollutants for the industry, the permitted fuels, the pollution control devices to be installed, the frequency of stack monitoring, and the reporting obligations. A unit that has expanded capacity, added a boiler or changed fuel without amending its consent is in breach even if its emissions are clean.

Read the consent conditions before reading the notice. In air pollution matters that reach Advocate B.K. Singh, the most common hidden problem is not an exceedance but a gap between the consent and the plant as it actually runs: a second DG set never added to the consent, a coal-fired boiler where the CTO says PNG, or a stack that was relocated during a renovation. Fixing that gap, through an application to amend or renew the consent, often matters more than winning the argument about one sample. Our page on consent to establish and consent to operate explains the consent process.

Operating with an expired consent is treated seriously. Renewal applications should be filed well before expiry, with fees and compliance reports, and the acknowledgment kept. Some states treat a renewal application filed in time as deemed consent until decided; others do not. Check the state's rules rather than assuming.

Stack emissions: standards, monitoring and sampling

Stack emissions are the pollutants released through chimneys from boilers, furnaces, kilns, incinerators and process vents. The standards come from the Environment (Protection) Rules for the specific industry, or the general standards where no specific standard exists, as applied in the consent. Typical parameters are particulate matter, SO2, NOx, carbon monoxide and, for some industries, specific pollutants such as fluorides, acid mist or heavy metals.

Units must have stacks monitored at the frequency the consent requires, usually by a laboratory recognised under the Environment (Protection) Act or accredited by NABL. Keep the reports in order, with sampling dates, the operating load at the time and the instrument calibration. A clean report taken at half load is weak evidence against an inspection sample taken at full load.

When a board inspection finds an exceedance, look closely at how the sample was taken. Was the occupier given notice and allowed to be present? Was the sampling port at the correct location on the stack? Was the plant running at normal load? Were the samples sealed, labelled and sent to the laboratory in the manner required? Was the analyst's report supplied? Procedural lapses do not excuse real pollution, but they matter when the board treats a single result as proof of continuous violation.

Fugitive emissions: dust that never goes up a stack

Fugitive emissions are pollutants released other than through a stack: dust from raw material handling, crushing and screening, conveyor transfer points, open storage of coal, clinker or fly ash, vehicle movement on unpaved roads, loading and unloading, and leaks from process equipment. Many industry standards, such as those for cement, stone crushers, iron and steel, and coal handling, include specific fugitive emission limits and required control measures.

Boards enforce fugitive emission norms mostly through inspection: visible dust, uncovered stockpiles, lack of water sprinkling or dry fog systems, broken enclosures at transfer points, unpaved internal roads, absence of a green belt, and ambient monitoring results at the boundary. Because the evidence is often photographs and the inspecting officer's observations, the reply needs evidence of its own: the maintenance log of sprinklers and enclosures, ambient air monitoring reports, purchase records for control equipment, and photographs taken the same day.

In NCR, fugitive dust from industry and construction is also covered by CAQM directions and GRAP measures, and the board may treat dust violations during high-pollution periods far more severely. Construction projects face a parallel regime of dust control rules and penalties; see our page on construction dust and C&D waste violations.

OCEMS: online continuous emission monitoring

OCEMS is the online system that measures stack emissions continuously and transmits the data in real time to the servers of the CPCB and the state board. In 2014, the CPCB directed the 17 categories of highly polluting industries, including cement, iron and steel, thermal power, aluminium, zinc, copper, fertiliser, oil refineries, petrochemicals, pulp and paper, sugar, distilleries, pharmaceuticals, pesticides, dyes, chlor-alkali and tanneries, to install online monitoring of emissions and effluents. Common effluent treatment plants, sewage treatment plants and common hazardous and bio-medical waste incinerators were also covered. State boards have since extended the requirement to other units through consent conditions.

The system produces two kinds of notices. Exceedance alerts are generated automatically when a parameter crosses its limit, and the unit is expected to respond and correct. Connectivity notices arise when data stops flowing, when data availability falls below the required level, when the analyser is not calibrated, or when the readings look flat or unrealistic and suggest tampering. Each type needs a different reply. An exceedance during start-up, with an explanation from the control room logs, is very different from three weeks of no data.

How far OCEMS readings alone can support closure or penalty is still argued, because analysers drift, require periodic calibration against manual stack sampling, and can be affected by moisture or placement. Boards usually back serious action with manual sampling, but repeated unexplained exceedances in OCEMS data are themselves treated as evidence of non-compliance. Treat OCEMS data as a record that will be read by the regulator, the NGT and possibly the Supreme Court: keep calibration certificates, downtime logs and correspondence with the vendor. The same approach applies to online effluent monitoring for water; see our page on water pollution, effluent discharge and ETP compliance.

Common emission notices and how to respond

Diesel generator sets

DG sets are regulated by the Environment (Protection) Rules, which set emission limits and noise limits for generator sets and require type approval and conformity certification before sale. The current emission norms for gensets up to 800 kW, commonly called CPCB IV+, apply to new sets manufactured from July 2023. Older sets are not automatically illegal, but they are under increasing pressure, especially in NCR. Noise rules require an acoustic enclosure or treatment of the room, with limits on noise at one metre from the enclosure.

The exhaust stack of a DG set must be of the minimum height worked out under the CPCB formula, which depends on the height of the building and the rating of the set. Low stacks discharging into a neighbour's balcony are a frequent source of complaints from residents and of notices to housing societies, hotels, hospitals, malls and offices. Consent conditions often specify the number and capacity of DG sets; an extra set added later must be brought into the consent.

In NCR, the Commission for Air Quality Management has restricted the use of diesel generator sets, allowing larger sets to run only if converted to gas or dual-fuel mode or fitted with retrofitted emission control devices, and GRAP stages tighten the restrictions further, with exemptions for emergency and essential services. The capacity bands, permitted technologies and exemptions have changed several times, so check the latest CAQM direction for your set before relying on any summary. For noise complaints and DG set noise conditions, see our page on noise pollution complaints and noise NOC.

NCR rules: CAQM, GRAP and approved fuels

Industries and buildings in Delhi, Noida, Greater Noida, Ghaziabad, Gurugram, Faridabad and the rest of NCR face a second layer of regulation from the Commission for Air Quality Management. CAQM issues statutory directions on fuels, DG sets, industrial emissions, brick kilns, construction dust, vehicles and stubble burning, and its directions bind the state boards. Its flying squads inspect units and recommend closure where they find serious violations.

The Graded Response Action Plan (GRAP) sets out escalating restrictions linked to the Air Quality Index: Stage I when AQI is poor (201 to 300), Stage II when very poor (301 to 400), Stage III when severe (401 to 450) and Stage IV when severe plus (above 450). Higher stages bring restrictions on DG sets, construction and demolition, certain industries and vehicles. A unit that operates normally in September can find itself shut under a GRAP order in November, so the compliance plan has to work at every stage.

CAQM has also directed industries in NCR to use only fuels on its approved list, which centres on PNG and certain clean fuels such as biomass in specified forms, and has required conversion of brick kilns to cleaner technology. A unit still burning coal or another unapproved fuel in NCR is exposed to closure regardless of its stack readings. The Supreme Court continues to monitor Delhi air pollution in M.C. Mehta v Union of India, and its orders on GRAP enforcement bind all authorities. For general compliance in NCR, see our page on environmental compliance and litigation.

What a notice can lead to: closure, compensation and penalty

Board action usually escalates in steps. An inspection report leads to a show cause notice; an unsatisfactory reply leads to directions under section 31A of the Air Act or section 5 of the Environment (Protection) Act, which can include closure, sealing and disconnection of electricity and water. Boards also demand environmental compensation, worked out under CPCB's methodology from the period of violation, the pollution potential of the industry and its scale. In Delhi Pollution Control Committee v Lodhi Property Co. Ltd (2025), the Supreme Court held that pollution control boards can impose restitutionary and compensatory damages for environmental harm under their direction powers, subject to a fair procedure and properly framed rules.

Monetary penalties under the amended Air Act and Environment (Protection) Act are now imposed by an adjudicating officer after an inquiry, and appeals lie to the NGT on depositing part of the penalty. Prosecution has not disappeared for every contravention, so check which provision the notice cites. Separately, the NGT can direct compensation in an original application brought by residents or taken up on a news report.

Each of these has its own reply and its own remedy. For the notice stage, see pollution board show cause notice reply; for closure, closure notice and closure order; for compensation demands, challenging or claiming environmental compensation.

Replying to an air pollution notice

The reply is often the only chance to put the unit's side before an order is passed. Treat it as the first pleading in a case that may reach the NGT.

1. Read the notice and the inspection report

   Identify exactly what is alleged, which provision is cited and what action is proposed. Ask in writing for the inspection report, sample results and photographs if they were not attached. Note the reply deadline.

2. Check against the consent

   Compare each allegation with the consent conditions and the standards that apply. Many notices quote the wrong standard or an old consent. Note where the unit was in breach and where it was not.

3. Collect the evidence

   Gather recognised-lab stack reports, OCEMS data and calibration records, APCD logs, fuel records, DG set certificates and dated photographs. Get a fresh stack monitoring done if the last one is old.

4. Fix what is genuinely wrong

   Where there is a real problem, start the correction at once and document it: purchase orders, installation reports, repair records. A reply that shows action taken carries far more weight than one that only argues.

5. Draft the reply

   Answer each allegation in order, with documents. Challenge procedural defects in sampling where they exist, explain exceedances with logs, and give a time-bound plan for anything pending. Ask for a personal hearing.

6. Attend the hearing and follow up

   Attend with the technical person who runs the plant. After the hearing, file any further documents promised and keep the board informed of completion of corrective work.

7. Challenge an adverse order quickly

   If a closure direction, compensation order or penalty follows, note the appeal period at once and consider urgent relief. Appeals and NGT applications have short time limits.

Never ignore a notice because the unit was already compliant by the time it arrived. Silence is read as admission, and orders are passed on the record as it stands.

Appeals and challenges

An order of a state board under the Air Act, such as a consent refusal, can be appealed to the appellate authority under section 31 within 30 days; a direction under section 31A is usually challenged by a writ petition in the High Court, because the Supreme Court held in 2019 that the NGT has no appeal power over it. The appellate authority's order can in turn be appealed to the National Green Tribunal under section 16 of the NGT Act within 30 days, extendable by 60 days for sufficient cause. Directions under section 5 of the Environment (Protection) Act and orders of CAQM are appealable to the NGT directly. Penalty orders of the adjudicating officer go to the NGT on deposit of a part of the penalty.

Where a closure order has been passed without notice, or a unit has been sealed and disconnected without a hearing, urgent relief is sometimes sought from the NGT or, for violations of natural justice and jurisdiction, from the High Court under Article 226. The right forum depends on the order and the grounds, and filing in the wrong one wastes days a closed unit cannot afford. Tribunals usually grant interim relief, if at all, on conditions such as an undertaking, a bank guarantee, a deposit towards compensation or a joint inspection.

Matters involving Delhi air pollution sometimes go to the Supreme Court within the M.C. Mehta proceedings or by appeal from the NGT under section 22 of the NGT Act within 90 days; see Supreme Court cases.

Evidence that holds up

In emission cases the evidence is mostly technical, and its form matters. Stack monitoring reports should come from a laboratory recognised under the Environment (Protection) Act or accredited by NABL, with the sampling method, the operating load and the instrument calibration shown. OCEMS data relied on in a reply or appeal is an electronic record, and where it is produced before a tribunal, the requirements of section 63 of the Bharatiya Sakshya Adhiniyam 2023 on certificates for electronic records should be kept in mind.

Photographs and videos should be dated and taken by someone who can confirm them on affidavit. Purchase and installation records for pollution control equipment show what was done and when. Where the board and the unit disagree on facts, a joint inspection by the board with the unit's representatives present, or an inspection directed by the NGT, is often the fairest way to settle the dispute. For units that face surprise inspections, our page on pollution board inspections and raids explains what to do on the day.

Documents to keep ready

How it changes by industry and occupier

Iron and steel, including induction furnaces and rolling mills. Fugitive emissions from charging and tapping, slag handling and scrap yards are the usual issues, along with fuel use in reheating furnaces. Secondary steel units in NCR face the approved-fuel rules and frequent CAQM inspection.

Cement and grinding units. Dust from clinker and fly ash handling, packing plants and truck movement dominates. Stack limits for kilns and coolers are monitored through OCEMS.

Thermal power and captive plants. SO2 and NOx norms and flue gas desulphurisation have been the main issues; timelines and applicability have been revised more than once, so check the current MoEFCC notification. Fly ash handling also produces fugitive emissions.

Stone crushers, brick kilns and hot mix plants. Siting criteria, enclosures, water sprinkling and fuel are central. In NCR, brick kilns must use cleaner technology and approved fuel, and GRAP stages can close them.

Chemical, pharmaceutical and paint units. Volatile organic compounds, odour, solvent recovery and process vents attract complaints from nearby residents as much as board action.

Hotels, hospitals, malls, offices and housing societies. The air issues are usually DG sets, boilers and kitchen exhaust. Housing societies and builders also face sewage and construction issues on other pages, but DG stack height and noise generate most resident complaints.

Outside NCR. The same Air Act and Environment (Protection) Rules apply across India, enforced by the state board, and industrial clusters in places such as Haldia, Raipur or Ludhiana face their own action plans under the National Clean Air Programme. CAQM and GRAP apply only in NCR and the adjoining areas covered by the Act.

For residents affected by air pollution

People living near a polluting unit have several options, and they work best in sequence. Start with a written complaint to the state board, with photographs, videos and dates; CPCB's Sameer app and, in Delhi, the Green Delhi app also accept complaints. Ask for the inspection report under the Right to Information Act if no action follows. Many units correct problems once the board inspects.

If the board does not act, an original application before the NGT under section 14, for a substantial question relating to the environment, or section 15, for relief and compensation, is the usual next step. The NGT often appoints a joint committee of the CPCB, the state board and the district administration to inspect and report. Residents should be ready to show specific harm, such as dust deposits, visible emissions, odour or health effects, with as much documentation as they can gather. Writ petitions in the High Court are used where the issue involves a public authority's failure to enforce the law. See filing a case in the NGT for procedure.

Mistakes units make with air pollution notices

• Ignoring the first notice. The second document is often a closure direction. Reply in time, even if only to ask for the inspection report and a hearing.
• Running beyond the consent. Extra DG sets, new boilers or a fuel change without consent amendment are violations in themselves.
• Treating OCEMS as the vendor's problem. The unit is answerable for data gaps and exceedances. Keep downtime logs and push the vendor in writing.
• Relying on old stack reports. A report from eight months ago at part load will not answer an inspection result today.
• Arguing without fixing. Tribunals respond to corrective action with dates and invoices, not to arguments alone.
• Forgetting GRAP. A compliance plan that ignores Stage III and IV restrictions in NCR will fail in winter.
• Missing the appeal period. Thirty days runs fast when a unit is sealed and the management is dealing with workers and buyers.

What to do this week if you have received an air pollution notice

• Note the reply deadline and diarise it with a margin of two or three days.
• Ask the board in writing for the inspection report, sample results and photographs if not attached.
• Pull out the current consent and check each allegation against its conditions.
• Download OCEMS data for the period, with calibration and downtime records.
• Commission a fresh stack monitoring by a recognised or NABL-accredited laboratory.
• Start correcting any genuine fault and keep invoices and photographs.
• In NCR, check the current CAQM directions and GRAP stage for your industry and DG sets.
• Prepare a reply that answers each point and asks for a personal hearing.

The next step

Air pollution notices are won or lost on records that exist before the notice arrives: the consent, the monitoring reports, the maintenance logs and the OCEMS data. When Advocate B.K. Singh reviews such a notice, the first question he asks is whether the plant as it actually runs matches the consent, because that decides how much of the reply can be argued and how much has to be fixed. A unit that answers promptly, admits what is wrong and shows what it has done is in a far better position before the board, the NGT and any higher court.

If you want a notice or a consent condition checked before you reply, the team of Advocate B.K. Singh at Legals365 can review the papers and tell you the next step: talk to a lawyer. For state board notices generally, see state pollution control board notices.

Dealing with the CPCB

The Central Pollution Control Board is the national pollution regulator. It was constituted under the Water (Prevention and Control of Pollution) Act 1974 and works under the Air Act 1981 as well, with powers delegated under the Environment (Protection) Act 1986. It sets standards, coordinates and guides the state pollution control boards, resolves disputes between them, and runs the national monitoring networks for air and water quality. For day-to-day consents an industry deals with its state board or, in Delhi, the Delhi Pollution Control Committee, but the CPCB decides much of what those consents demand.

Three of its functions matter most to businesses. First, it classifies industries into red, orange, green and white categories, which decides how strict the consent regime is and how often a unit is inspected. Second, it can issue directions, including closure or stopping power and water supply, under section 5 of the Environment (Protection) Act, and it can direct state boards under section 18 of the Water and Air Acts. Third, it runs the centralised portals for extended producer responsibility under the rules on plastic packaging, e-waste, batteries, tyres and used oil, where producers, importers and brand owners register, file returns and buy or generate EPR certificates.

EPR enforcement has become a frequent source of notices. A brand owner that has not registered, has under-reported the quantity placed on the market, or has not met its recycling targets can face environmental compensation calculated under CPCB guidelines and suspension of registration. Recyclers and processors face scrutiny of the certificates they issue, and the CPCB has cancelled registrations where it found fake or inflated claims. Keeping sales data, invoices and recycler certificates consistent is the main defence.

The CPCB also appears often as a party or technical adviser in litigation. The NGT regularly appoints joint committees with the CPCB and the state board to inspect sites and report, and in Delhi NCR the CPCB works alongside the Commission for Air Quality Management on dust, industrial fuel and vehicle norms. Its flying squads inspect industries in the NCR and report violations. Industries in the seventeen highly polluting categories must connect online monitoring systems to CPCB servers, and data from those systems frequently forms the basis of a notice.

A notice or direction from the CPCB should be answered in writing within the time given, with data, photographs and a compliance plan. Directions and compensation orders can be challenged before the NGT or, where the complaint is about lack of hearing or jurisdiction, before the High Court in a writ. Ignoring the notice and waiting for the state board to sort it out rarely works.

Frequently asked questions

What is OCEMS and who must install it?

OCEMS is online continuous emission monitoring that sends stack data in real time to the CPCB and state board servers. The CPCB required the 17 categories of highly polluting industries, along with common treatment plants and incinerators, to install it, and state boards have extended it to other units through consent conditions.

What should I do after an OCEMS exceedance alert?

Check the control room logs and the analyser calibration, correct any process or equipment fault, and record what you did. If the board issues a notice, reply with the logs, calibration certificates and manual stack monitoring results.

Can a pollution board close my factory for air pollution?

Yes. Under section 31A of the Air Act and section 5 of the Environment (Protection) Act, boards can direct closure and stoppage of electricity and water. Ordinarily a notice and an opportunity to reply come first, except in cases of grave environmental harm.

Where do I appeal against a closure order under the Air Act?

An order of the state board can be appealed to the appellate authority under section 31 within 30 days, and from there to the NGT. Directions under the Environment (Protection) Act and orders of CAQM go to the NGT directly.

Are diesel generator sets banned in Delhi NCR?

Not entirely, but CAQM has restricted them, allowing larger sets to run only with gas, dual-fuel or retrofitted emission control, and GRAP stages tighten the limits. Emergency and essential services have exemptions. Check the latest CAQM direction for your set's capacity.

What are fugitive emissions?

Pollutants released other than through a stack, such as dust from material handling, crushing, conveyors, open storage and vehicle movement. Many industry standards prescribe specific controls, and boards enforce them mainly through inspection.

Can pollution boards demand environmental compensation?

Yes. In 2025 the Supreme Court held that pollution control boards can impose restitutionary and compensatory damages under their direction powers, subject to fair procedure. The amount and its calculation can still be challenged.

Is there still jail for Air Act violations?

Since April 2024 most Air Act contraventions attract monetary penalties fixed by an adjudicating officer instead of imprisonment, after the Jan Vishwas amendments. Prosecution has not been removed for every provision, so check the section cited in your notice.

What is GRAP and how does it affect industries?

The Graded Response Action Plan imposes staged restrictions in NCR as AQI worsens, from Stage I at poor air quality to Stage IV at severe plus. Higher stages restrict DG sets, construction and certain industries, and can close units using unapproved fuels.

How do I complain about a factory polluting the air near my house?

File a written complaint with photographs and dates to the state pollution control board, or use the CPCB Sameer app. If the board does not act, an original application can be filed before the NGT, which often orders a joint inspection.

Is OCEMS data enough to penalise a unit?

Boards treat repeated unexplained exceedances as evidence, but analysers drift and need calibration, so serious action is usually backed by manual stack sampling. A unit should keep calibration and downtime records to explain its data.

What is the time limit to approach the NGT on air pollution?

Six months from the cause of action for an original application under section 14, extendable by 60 days; 30 days for an appeal under section 16, also extendable by 60 days. Claims for relief and compensation under section 15 have a five-year limit.

Is the CPCB or the state board responsible for my factory's consent?

The state pollution control board, or the DPCC in Delhi, issues consent to establish and operate. The CPCB sets the standards and categories, runs the EPR portals and can issue directions directly, especially to highly polluting units or after its own inspections.

What is EPR registration with the CPCB?

Producers, importers and brand owners of plastic packaging, electronic goods, batteries and certain other products must register on the CPCB's EPR portals and meet yearly collection or recycling targets. Failure to register or to meet targets can lead to environmental compensation and suspension of registration.