What is Stack Emission Monitoring?
Stack emissions monitoring, often referred to as stack testing or stack sampling, plays a vital role in precisely measuring and analysing the pollutants released from industrial stacks, chimneys and exhaust systems. It determines actual emissions from your process and confirms that abatement systems are functioning as designed. This essential process not only helps your facility meet stringent EPA licence requirements, environmental permit standards and Industry Emission Directive (IED) but also safeguards air quality and supports your commitment to environmental responsibility.
Industry-Leading Stack Emission Monitoring for Compliance & Environmental Performance
Air Scientific Limited is ISO/IEC 17025 and INAB (319T) accredited for stack emission monitoring and analysis. We provide comprehensive stack emissions monitoring and flue gas analysis for a range of industries across Ireland and the United Kingdom. With over 30 years of direct industry knowledge, using advanced emissions testing equipment, Air Scientific has completed thousands of stack emissions projects. Our highly knowledgeable team combines deep technical expertise with practical experience to deliver precise, reliable and fully compliant stack emissions testing tailored to your unique industrial process. Our monitoring programmes are tailored to the specific processes, fuels and emission sources operating on your site. We work across all major regulated sectors, including waste-to-energy, pharmaceutical manufacturing, chemical processing, food production, metals, energy generation and wastewater treatment. Whether you require scheduled compliance monitoring, commissioning tests, troubleshooting assessments, or independent verification, we deliver precise, defensible emissions data that stands up to regulatory scrutiny.
Accredited Expertise and Proven Capability
At Air Scientific, our team uses internationally recognised reference methods and fully accredited sampling techniques for all regulated pollutants streams. This work ensures your results are defensible, audit-ready and ensures full compliance of all emission parameters as per the EPA AG1, AG2, AG3 as specified in your EPA licence or environmental permit, the EU Industrial Emissions Directive (IED) requirements and international best practices for industrial emissions control.
How Air Scientific Performs Stack Emissions Monitoring
Our methodology combines accredited stack sampling with advanced analytical capability:
Process Review & Method Planning – We assess your permit, AG2 requirements and process design to define the correct monitoring strategy.
On-Site Accredited Sampling – Using reference methods (EN/ISO/CEN/USEPA), site specific sampling methods and calibrated analysers, we capture high-integrity data directly at the stack.
Laboratory Analysis – Parameters such as metals, organics and dioxins are analysed under ISO/IEC 17025 accredited conditions for complete traceability.
Compliance Interpretation – Results are assessed against permit limits, BAT-AELs and regulatory thresholds with clear, actionable AG2 compliant reporting.
Technical Guidance & Support – Our specialists support you through audits, EPA interactions, optimisation decisions and corrective actions if required.
This structured approach ensures every dataset is accurate, EPA compliant, defendable and operationally meaningful.
What We Measure
Our stack emissions testing services routinely measure a wide range of regulated pollutant parameters including:
Particulate Matter (PM10, PM2.5 and Total Suspended Particulates)
Nitrogen Oxides (NOx: NO and NO₂)
Sulphur Oxides (SO₂)
Carbon Monoxide (CO) and Carbon Dioxide (CO₂)
Volatile Organic Compounds (VOCs) including methane and non-methane hydrocarbons
Dixons & Furans
Formaldehyde
Hydrogen Sulphide (H₂S)
Mercaptans
Amines
Total Isocyanates (HDI, MDI, TDI)
Ammonia (NH₃)
Hydrogen Chloride (HCl) and other acid gases such as HF, HNO3, H2O2
Heavy Metals and Trace Elements
Oxygen (O₂)
Odour and Odorous Compounds (sampled and analysed to EN 13725:2022)
Reduced Sulphur Compounds
Total Organic Carbon
Total Particulate Matter
Fluoride
TU-Luft Organics (Class I, II, III)
Halogenated or Non-Halogenated Compounds
Measurements in Stack Emissions Monitoring
In addition to the above key pollutants, we also perform essential velocity, pressure, temperature, moisture and flow measurements within stacks. Accurate flow measurement, combined with precise velocity, temperature and moisture monitoring, is a vital aspect of stack emissions monitoring. These physical measurements directly influence the calculation of pollutant mass emissions and ensure compliance with EPA licence requirements. Using advanced velocity probes, pitot tubes and anemometers, we measure gas velocity profiles across the stack cross-section to capture flow variability and determine stack gas speed with high precision. Continuous monitoring of stack gas temperature allows us to accurately calculate gas density, essential for converting volumetric flow to standard conditions. Moisture content in stack gases can be determined using a gravimetric method involving impingers, pre-weighed silica gel and knob weights. Accurate determination of moisture is essential because it directly affects the volume and density of the gas stream.
Our comprehensive flow measurement approach integrates these parameters with pressure and cross-sectional data to calculate the volumetric and mass flow rates of stack gases. This data is combined with pollutant concentrations and is used to deliver precise emissions rates, crucial for environmental reporting and permit compliance.
Stack Emissions Monitoring Methods
We employ a wide range of accredited stack emission monitoring techniques designed to suit your specific monitoring and licence requirements. Below are some of the accredited methods that Air Scientific utilises:
Iso-Kinetic Sampling
This specialised technique is used to collect representative samples of particulate matter and associated gases. During sampling, the velocity of the gas entering the sampling probe is carefully maintained equal to the velocity of the gas in the stack, ensuring that particles enter the probe in proportion to their presence in the gas flow. This controlled approach prevents over or under-sampling of particles, providing accurate measurement of total particulate concentration, particle size distribution and associated chemical composition. This is completed using equipment like the Dadolab ST5 and TCR Tecora G4.
Non-Iso-Kinetic Sampling
This method is used to collect and analyse gaseous or vapour-phase pollutants. It involves extracting a sample at a controlled flow rate independent of the stack gas velocity, making it suitable for applications where particulate loading is minimal or where the focus is solely on gas-phase constituents. This technique enables accurate quantification of compounds such as Sulphur Dioxide (SO₂), Hydrogen Chloride (HCl), Ammonia (NH₃), Volatile Organic Compounds (VOCs) and Moisture content.
Impingers
The drawing of a known volume of gas through a series of glass impingers (bubblers) which contain specific chemical solutions. As the gas passes through these solutions, targeted contaminants are absorbed, captured or reacted chemically, allowing for precise quantification of pollutant concentrations in the emission stream. This vital for acid gases and trace organics.
Wet Chemistry
This laboratory based analytical technique is used to quantify soluble or reactive pollutants collected from industrial stacks, ducts and or exhaust streams. During stack sampling, emissions are drawn into liquid media typically impingers where compounds such as Acid gases (SO₂, HCl, HF), Ammonia, Heavy Metals, Organics and other water-soluble species are captured without altering the stack’s operating conditions. The collected samples are then analysed using titration, colorimetry or other chemical methods to provide accurate, reproducible and defensible measurements.
Extraction Sampling
This sampling technique is used to collect direct representative portions of stack or process emissions for laboratory analysis. Without altering the natural operating conditions of the source, this method involves extracting a measured gas volume through a probe into a controlled sampling train, where target compounds such as Volatile Organic Compounds (VOCs), Acid gases or other gaseous pollutants are captured using impingers, sorbent tubes or other media. As stack temperature, velocity and and pressure remain undisturbed during sampling, the results accurately reflect true emission characteristics.
Gravimetric Analysis
Determining the concentration of particulate matter in an air or gas stream by measuring its mass. In this method, a precise volume of gas is drawn through a pre-weighed filter medium that captures suspended particles. Following sampling, the filter is conditioned and re-weighed under controlled laboratory conditions to calculate the mass of particles per unit volume of air or gas.
Instrumental Gas Analysis
Using advanced Horiba analysers featuring Non-Dispersive Infrared (NDIR), Chemiluminescence, Paramagnetic and Zirconium oxide cell sensors. Flame Ionization Detectors (FID) for VOCs, and Testo Electrochemical Cells for NOx, CO, CO₂ and O₂.
Fourier Transform Infrared Spectroscopy (FTIR)
Real-time detection of multiple gases including NOx, SOx, CO, CO₂ and VOCs.
Continuous Emissions Monitoring Systems (CEMS)
At Air Scientific, we also provide full support for Continuous Emissions Monitoring Systems (CEMS). Our services are designed to help industrial operators maintain full compliance with regulatory requirements while maximising the reliability and accuracy of their emissions data. We assist with QUAL2, QUAL3 and Annual Stack Tests (ASTs) to validate your CEMS performance, ensuring that all measurements meet the stringent standards required for regulatory reporting and EPA licence compliance.
By conducting these performance evaluations, we confirm that your CEMS equipment operates consistently and precisely, detecting pollutants such as NOx, SO₂, CO, CO₂, particulate matter and VOCs in real time. Our team not only verifies the accuracy of your system but also provides expert guidance on calibration, data interpretation and optimisation, helping you avoid operational discrepancies, ensure continuous compliance and generate defensible emissions data for audits or inspections.
Why Stack Emissions Monitoring Matters for Your Facility
Full Regulatory Compliance Ensures full compliance with EPA and its AG2 requirements and all associated EU IED protocols.
Protecting Your Licence and Reputation By consistently staying within emission limit values, our accredited stack monitoring safeguards your EPA licence and demonstrates a commitment to responsible environmental management.
Operational Efficiency and Risk Prevention Identification of inefficiencies in combustion and or abatement systems before they escalate into costly issues. Continuous and periodic monitoring provides early detection of operational deviations, enabling corrective action and process optimisation.
Actionable Data for Improvement ISO/IEC accredited, measurable emissions data is key to making informed operational decisions. We provide insights that allow you to optimise industrial processes, improve abatement efficiency and benchmark performance across operations.
Supporting Environmental Planning and Community Engagement Our monitoring supports dispersion modelling and community impact assessments, providing defensible data to assess environmental impacts, manage public communication and implement targeted mitigation measures.
Building Trust with Regulators and Stakeholders With accurate, defensible and audit-ready data, Air Scientific ensures that your facility builds trust with EPA inspectors, auditors and other regulatory authorities. Our AG2 compliant reporting demonstrates both regulatory compliance and environmental responsibility.
Why Choose Air Scientific
Why Choose Air Scientific For Your Stack Emissions Testing?
INAB Accredited & EPA Compliance ISO/IEC 17025 accredited comprehensive testing across all regulated stack emissions parameters, strictly following the latest EPA licenses and guidance notes.
Industry Experience Over 30 years of specialist stack testing experience and knowledge across all regulated sectors.
Extensive Sector Knowledge Deep understanding of EPA AG2 , IED requirements and industrial permits.
Assurance Trusted by pharmaceutical, animal rendering, anaerobic digestion, landfills, refineries and many other industries for stack emissions monitoring.
Tailored Solutions Customized approaches to meet your unique stack emissions challenges and permit requirements.
Minimize Operational Disruptions Efficient scheduling and portable stack emissions equipment allow compliance testing with minimal impact on your production.
Odour Compliance Accredited odour sampling and analysis to the regulatory standard EN13725:2022.
Reporting Our reports follow the EPA AG2 compliant format, combining expert-level detail with clear, easy-to-follow presentation. You will receive precise and transparent stack emission results, so you know exactly what is happening with your emissions and can make informed decisions confidently.
Costing We offer solutions that are not only competitively priced but also highly efficient and effective, ensuring excellent value without compromising on quality or performance.
Relationships Extensive exclusive relationships and contracts with the leading laboratories and experts.
Proficiency Testing Participation in the National Physics Laboratory Stack Stimulation and EffecTech Stack Emissions Proficiency test to ensure precision, accuracy and reliability.