Introduction

The collection and analysis of emission samples is a critical enforcement mechanism under the Air (Prevention and Control of Pollution) Act, 1981. Accurate, procedurally sound sampling is essential for establishing proof of violation in court. The procedure is set out in Section 26 of the Air Act, supplemented by the Air (Prevention and Control of Pollution) Rules, 1982.

Who Can Collect Samples?

Under Section 24 (Power of Entry and Inspection) and Section 26, any person duly authorised by the SPCB or CPCB (an authorised officer or inspector) has the power to enter any premises at all reasonable times and collect emission samples from chimneys, ducts, flues, or other outlets.

Detailed Step-by-Step Procedure

Step 1 — Authority to Enter Premises: Under Section 24, an authorised officer of the SPCB can enter any premises including an industrial plant at all reasonable times. He may be accompanied by assistants (e.g., technical experts). The officer has the authority to:

• Inspect any chimney, duct, flue, control equipment, or industrial plant.
• Examine any records, registers, documents, or instruments related to emission control.
• Conduct searches and seize equipment that may furnish evidence of an offence.

Step 2 — Notice to the Occupier: Before taking a sample, the authorised officer must give the occupier (or his authorised representative) a written notice of his intention to take an emission sample. This ensures transparency and gives the occupier an opportunity to be present during collection.

Step 3 — Collection of Emission Sample: The sample is collected from a chimney, duct, flue, or any other outlet in the presence of the occupier or his authorised representative. The sample must be collected in a clean container appropriate for the type of emission (solid, liquid, or gaseous substance).

Step 4 — Division into Three Equal Parts: The collected sample is divided into three equal parts. Each part is:

• Placed in a clean, airtight container.
• Sealed immediately to prevent tampering or contamination.
• Labelled with the date, time, location, name of the industry, and signature of the officer and occupier (or representative).

Step 5 — Dispatch to Laboratory:

• Part 1 is sent by the authorised officer to a government-recognised or NABL-accredited laboratory for analysis. The laboratory must be recognised under the Air Act or Environment (Protection) Act.
• Part 2 is handed over to the occupier or his representative for independent analysis, if they choose.
• Part 3 is retained by the SPCB and can be produced in a court of law as exhibit/evidence if the matter goes to prosecution.

Step 6 — Laboratory Analysis: The laboratory analyses the sample for specified air pollutants — such as particulate matter (PM10, PM2.5), sulphur dioxide (SO2), nitrogen oxides (NOx), carbon monoxide (CO), volatile organic compounds (VOCs), and any other parameters as prescribed by the SPCB. The laboratory must follow prescribed methodologies and quality control standards (calibration of instruments, use of standard procedures).

Step 7 — Analysis Report: The laboratory prepares a detailed analysis report that includes:

• Parameters tested and methodology used.
• Results obtained for each parameter (numerical values).
• A comparison against prescribed emission standards.
• Compliance or non-compliance status.
• Signed by the laboratory technician and a designated officer of the SPCB.

Records of all samples, analysis, and reports are maintained for a minimum of five years and are subject to audit by the SPCB.

Step 8 — Admissibility in Legal Proceedings: The sample analysis is admissible as evidence in legal proceedings only if the above procedure has been strictly followed — particularly the three-part division, proper sealing, labelling, and dispatch. If the procedure is not followed, the report may be challenged and excluded from evidence.

Action against Defaulters

If the analysis report shows that emissions exceed prescribed standards:

• The SPCB issues a show cause notice to the industry.
• The SPCB may issue a direction under Section 31A — for closure, prohibition, or regulation of the plant, or stoppage of electricity/water/fuel supply.
• The SPCB can initiate criminal prosecution in the Judicial Magistrate's court under Section 37 of the Air Act. Penalty: imprisonment up to 3 months and/or fine up to Rs. 10,000 for first offence; up to 6 months (and up to 1 year) for subsequent offences. Continuing offence: Rs. 5,000 per day additional fine.
• Part 3 of the sample (retained by SPCB) is submitted as physical evidence in court.

Significance of the Procedure

The three-part sampling procedure ensures:

• Fairness — the occupier gets an independent copy (Part 2) for its own analysis and defence.
• Integrity — the sealed Part 3 is an untouched chain-of-custody sample for court.
• Scientific reliability — analysis by a recognised laboratory ensures credible results.
• Deterrence — systematic monitoring discourages non-compliance.

Conclusion

The sample collection procedure under Section 26 of the Air Act is a meticulously designed, legally rigorous process that balances the need for effective environmental enforcement with the rights of the accused industry. Strict adherence to the prescribed steps — notice, collection in presence of occupier, three-part division, sealing, labelling, and certified laboratory analysis — is mandatory for the results to be admissible in court and for successful prosecution of air pollution offenders.