Facilities, factories, and industrial zones must conduct air emission monitoring, control sources continuously, and maintain stable monitoring data effectively.

1. Overview of air emission monitoring

In the context of an increasingly strict legal framework on environmental protection, businesses not only need to treat emissions to meet standards but also must monitor, measure, and manage emission data in compliance with legal requirements.

According to Article 98 of Decree 08/2022/ND-CP in Appendix XXIX and the additional updates in Decree 48/2026/ND-CP, many entities with emission flow rates or source capacities falling within regulated thresholds are required to conduct automatic, continuous monitoring of industrial dust and emissions; at the same time, monitoring equipment must be tested, inspected, calibrated, and connected for data transmission in accordance with technical requirements.

1.1. Concept

Air emission monitoring is the activity of tracking, measuring, and assessing pollutant parameters in emission streams generated from production processes, fuel combustion, or waste treatment before being discharged into the atmosphere.

This activity may be carried out periodically through manual sampling or by using automatic, continuous monitoring systems installed directly at the emission source. In essence, air emission monitoring is not only to “measure whether emissions exceed standards or not” but also serves as a basis for businesses to effectively control the operation of treatment systems, demonstrate legal compliance, and support long-term environmental management.

In industrial practice, air emission monitoring focuses on post-treatment emission sources or at stacks and exhaust outlets of equipment, production lines, boilers, incinerators, power plants, steel plants, cement plants, chemical facilities, and many other types of manufacturing operations. The parameters to be controlled are not entirely the same for all facilities but are determined according to the type of production, characteristics of the emission source, environmental permit, and applicable technical regulations.

1.2. Main parameters in air emission monitoring

The basic parameters in air emission monitoring include dust, SO₂, NOx, CO, excess O₂, flow rate, temperature, and pressure. In addition, there are characteristic indicators depending on each type of production such as heavy metals, organic compounds, Dioxin/Furan, HCl, HF, or specific pollutants stated in the environmental permit. Appendix XXIX of Decree 08/2022 and QCVN 19:2024/BTNMT both show that parameters must be identified according to the specific emission source and should not be applied as a “fixed” list for every factory.

1.3. Purpose and significance of air emission monitoring

The greatest significance of air emission monitoring is that it helps businesses know exactly whether the treatment system is operating effectively, thereby detecting the risk of exceedances early, optimizing fuel and technology, and at the same time creating a data basis for inspections, examinations, environmental reporting, and handling violations when they arise.

Under current regulations, the results of dust and air emission monitoring are used to track and assess the effectiveness of treatment works, serve as a basis for declaring environmental protection fees where applicable, and serve as grounds for administrative penalties in the field of environmental protection where applicable.

2. Legal regulations related to air emission monitoring

2.1. Relevant legal documents

From a legal perspective, businesses should read in the following order: the framework provisions in the Law on Environmental Protection 2020; the detailed regulations on applicable entities, frequency, roadmap, and thresholds in Decree 08/2022/ND-CP and its amending decrees 05/2025/ND-CP and 48/2026/ND-CP; the technical monitoring regulations, system requirements, and data management in Circular 10/2021/TT-BTNMT; and the current emission limit regulation in Circular 45/2024/TT-BTNMT promulgating QCVN 19:2024/BTNMT, effective from July 1, 2025.

2.2. Entities required to conduct air emission monitoring

Not every business is required to install an automatic, continuous air emission monitoring system. This obligation is determined according to the type of production, dust and emission discharge flow rate, or the capacity of dust and air emission treatment works and equipment under Appendix XXIX issued together with Decree 08/2022/ND-CP, and must also be directly compared with the environmental permit of each project or facility.

In other words, to conclude whether a business is required to install CEMS, it is necessary to check the correct industry group, the correct threshold, and the correct legal documentation of the facility.

2.3. Basic requirements on parameters, frequency, data, and operation management

According to currently applicable regulations, projects and facilities falling within the threshold in Column 5 of Appendix XXIX must complete the installation of an automatic, continuous industrial dust and air emission monitoring system with surveillance cameras and direct data connection and transmission to the provincial-level environmental protection authority; for new investment projects falling within this threshold, from January 1, 2025, installation must be completed before trial operation of the waste treatment works.

In cases where an automatic, continuous system has been installed in accordance with regulations, after December 31, 2024, the facility is only exempt from periodic monitoring for parameters already monitored automatically and continuously. For facilities not subject to mandatory automatic installation, periodic monitoring must still be carried out at the frequency prescribed by law, in which different groups of parameters have different cycles and are not uniform in all cases.

3. Distinguishing automatic and manual air emission monitoring

3.1. What is automatic, continuous air emission monitoring?

Automatic, continuous air emission monitoring is a form of using a system of equipment installed directly at the emission source to measure, record, store, and transmit emission data in real time or near real time.

This system is usually integrated with operating parameters such as flow rate, temperature, pressure, O₂, and key pollutant parameters, while also being equipped with surveillance cameras and connected to transmit data to management authorities as required. This is the method required by law for certain large-scale emission sources or those with a high pollution risk for air emission monitoring.

3.2. What is manual air emission monitoring?

Manual air emission monitoring is the method of taking samples at the stack or discharge point by batch, then analyzing them using field equipment or in the laboratory.

This method is suitable for periodic assessment, verification of specific in-depth parameters, or application to facilities that are not required to install an automatic, continuous system. However, because the data is only available at specific times, this method cannot fully reflect emission fluctuations throughout the entire operating process.

Comparison of the advantages and disadvantages of the two methods

Manual monitoring has the advantage of lower initial investment cost, flexibility in analyzing many in-depth indicators, and suitability for facilities with small-scale or intermittent emission sources. In contrast, its weakness is fragmented data, difficulty in early detection of incidents, and strong dependence on the timing of sample collection.

Meanwhile, automatic, continuous monitoring allows 24/7 tracking, faster detection of abnormalities, and more convenient data storage and retrieval, but requires higher initial investment, synchronized technical infrastructure, and stricter maintenance and calibration procedures.

3.3. Why should businesses prioritize automatic, continuous monitoring?

From the perspective of management and legal compliance, businesses should prioritize automatic, continuous monitoring for emission sources that operate regularly, are large-scale, or are at high risk of emission fluctuations.

The reason is that this system both directly fulfills legal obligations for the group of entities subject to mandatory implementation and helps businesses continuously monitor treatment performance, reduce the risk of “exceeding standards at times when samples are not taken,” and at the same time create clear data records for working with management authorities. In other words, manual monitoring still has its role, but automatic monitoring is the more appropriate direction for modern environmental management and for facilities that need to proactively demonstrate compliance.

4. Application of air emission monitoring in industry

Air emission monitoring is widely applied at thermal power plants, industrial boilers, cement plants, steel plants, chemical plants, waste incinerators, and power generation or fuel combustion facilities on a large scale. QCVN 19:2024/BTNMT currently stipulates permissible limits for many groups of equipment and industrial emission sources, showing that emission control requirements are no longer focused only on a few specific industries but have been expanded toward a more integrated management approach.

In industrial zones or centralized emission treatment systems, air emission monitoring helps infrastructure investors and secondary enterprises monitor the operating efficiency of treatment systems, assess the level of compliance with technical regulations, and promptly handle abnormalities when they appear. In addition to its compliance role, monitoring data is also highly valuable for operational optimization, fuel cost control, adjustment of combustion regimes, and improvement of dust filtration, SO₂ removal, NOx removal, or other emission treatment stages.

5. Process for implementing an air emission monitoring system

The process of implementing a compliant air emission monitoring system should begin with reviewing the legal documents of the facility, especially the environmental impact assessment report, environmental permit, type of emission source, and applicable thresholds under Appendix XXIX.

After that, it is necessary to conduct an actual survey of the stack, sampling location, duct dimensions, temperature, pressure, flow rate, humidity, gas composition, operating regime, and on-site installation conditions in order to determine the appropriate air emission monitoring technology.

The next step is selecting the air emission monitoring system configuration: in-situ or extractive measurement, hot-wet or cold-dry, mandatory parameters and characteristic parameters according to the environmental permit, requirements for the station shelter, power supply, calibration gas, camera, data acquisition equipment, and the plan for connecting and transmitting data to the provincial-level environmental protection authority. At this stage, businesses should not choose equipment solely based on “price” but must select based on suitability with actual emission conditions and legal compliance objectives for air emission monitoring.

After installation, the system must be calibrated, inspected, tested, and assessed for stable operation before being officially put into operation. Current technical regulations also emphasize requirements for sampling points, sampling ports, safe working platforms, and the technical conditions of automatic, continuous air emission monitoring systems.

Throughout the operation process, businesses must maintain air emission monitoring data, maintenance, inspection, or calibration in accordance with regulations and keep complete records for inspections and examinations when required.

6. Reecotech accompanies businesses in implementing air emission monitoring solutions

In the context of increasingly strict emission management requirements, businesses need an air emission monitoring solution that not only complies with legal regulations but is also suitable for actual operating conditions at the factory. Selecting the right technology, the right parameters, and the right system configuration from the beginning will help reduce investment risks, improve monitoring efficiency, and ensure stable data during operation.

Reecotech is a provider of environmental monitoring solutions with the orientation of accompanying businesses from the stages of survey, consultation, design, and installation to operation support and system maintenance. We focus on delivering solutions suitable for the specific characteristics of each emission source, ensuring implementation feasibility and the ability to meet current environmental management requirements.

If your business is looking to learn about a suitable air emission monitoring solution for your factory or industrial zone, Reecotech is ready to provide consultation and propose an implementation plan tailored to your actual needs. Contact us now!

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