Stack Emission Testing

What is stack emission testing and why is it required?

Stack emission testing is the measurement of pollutant concentrations and mass flow rates in exhaust gases released from industrial stacks, vents, and chimneys. Under the National Environmental Management: Air Quality Act 39 of 2004 (NEM:AQA), facilities conducting Listed Activities (published under GN R893 of 2013, as amended) must hold an Atmospheric Emission Licence (AEL). AELs typically include conditions requiring periodic stack emission testing — usually annually or biennially — to demonstrate compliance with the national minimum emission standards for each listed activity. Failure to test is a direct breach of your licence conditions.

Which pollutants are tested during stack emission testing?

The pollutants tested depend on your AEL conditions and your listed activity. Common pollutants include particulate matter (PM), sulphur dioxide (SO2), oxides of nitrogen (NOx), carbon monoxide (CO), hydrogen chloride (HCl), hydrogen fluoride (HF), and volatile organic compounds (VOCs). For waste incineration activities, additional pollutants include dioxins, furans, heavy metals (mercury, cadmium, lead), and hydrogen bromide. Your AEL specifies exactly which pollutants must be measured and the emission limit for each.

What standards and methods are used for stack emission testing?

We apply the relevant SANS standards for source emission testing, including SANS 5399 (stationary source emissions — manual method of determination of gaseous compounds), SANS 1844 (particulate matter), and ISO methods where SANS standards are not yet published. For isokinetic sampling of particulate matter, we use methods consistent with US EPA Method 5 or ISO 9096. For gas analysis, we use extractive continuous or integrated sampling aligned to ISO 7935. The specific method is selected based on your AEL requirements and the pollutant being measured.

How often must stack emission testing be conducted?

The frequency is specified in your AEL conditions. Most AELs require annual testing, though some activities with lower risk profiles may require biennial testing. Your AEL may also require continuous emission monitoring (CEMS) for certain pollutants, with periodic stack testing used to calibrate and verify the CEMS. We track your testing schedule and provide advance notice so you never miss a deadline.

What happens if our emissions exceed the limits in our AEL?

An exceedance of your AEL emission limits is a non-compliance that must be reported to your licensing authority. Depending on the severity and frequency, the authority may issue a compliance notice, a variation notice to tighten conditions, or in serious cases, suspend or revoke the licence. We help you interpret the results, identify the likely cause (fuel quality, process conditions, control equipment performance), and develop a corrective action plan to present to the authority. Early detection through regular testing is far better than discovery during an inspection.

Do you also assist with Continuous Emission Monitoring System (CEMS) requirements?

Yes. Many AELs require CEMS for major pollutants like SO2, NOx, and particulate matter. We advise on CEMS specification, installation, QAL (Quality Assurance Level) requirements under EN 14181, and the annual surveillance testing (AST) that verifies CEMS accuracy against manual stack testing. We coordinate the manual stack testing that calibrates and validates your CEMS data.

Can you help us prepare for an AEL application or renewal?

Yes. For new AEL applications, baseline emission testing establishes the current emission profile and supports the impact assessment. For renewals, the emission test history demonstrates ongoing compliance. We coordinate the testing, prepare the emission data sections of the application, and liaise with the air quality officer at your licensing authority.

Why 2026 test results are judged more strictly

When the minimum emission standards were introduced, new plants had to comply from 1 April 2010, existing plants had to meet existing-plant standards by 1 April 2015, and existing plants had to meet the stricter new-plant standards by 1 April 2020. Operators could apply for a once-off postponement of the new-plant deadline of up to five years, but no postponement could remain valid beyond 31 March 2025.

That date has passed. Unless your atmospheric emission licence records a specific, lawful alternative, your stack test results are now compared with the new-plant limits for your listed activity. A facility that was comfortably compliant against a postponement limit in 2024 can be non-compliant on the same readings today.

Enforcement is becoming more complaint-driven

The Environmental Management Inspectorate inspected 5,643 facilities in 2023/24, about 30% more than the year before, with much of the increase in reactive inspections responding to complaints. For an emitting facility, that means a neighbour's complaint is increasingly likely to bring an inspector who will ask for your licence conditions, your latest emission test report and proof that exceedances were reported and acted on. The test report is the first document that either protects you or exposes you.

Your licence may now pull in dust as well

The National Dust Control Regulations, 2026 require listed-activity operators whose atmospheric emission licence calls for a dust management plan to submit one, and the approved plan is incorporated into the licence. Facilities that only thought about stacks now need to manage fugitive dust from stockpiles, conveyors and roads under the same licence. We cover both through our dust management plan and dust monitoring services.

What makes an emission test report stand up

A defensible report does four things. It tests the stacks and pollutants your licence actually lists, using the methods it specifies. It samples while the plant runs at representative operating conditions, and records those conditions, because a test during a low-load day proves little. It includes the stack parameters (temperature, flow, moisture, oxygen) needed to convert concentrations to the reference conditions in your licence, and mass emission rates where required. And the analysis comes from a SANAS-accredited laboratory with certificates attached.

The most common causes of resubmission are the first and third points: the wrong pollutant list, or results not corrected to the licence's reference conditions.

How we work

We don't do the stack sampling ourselves. The sampling and analysis are carried out by our accredited testing partner and a SANAS-accredited laboratory. Our role is to read your licence, plan the campaign, make sure the right stacks and pollutants are tested at the right time, review the report against your licence limits before it goes to the authority, and help you respond if a result exceeds a limit.