In this article, we will address issues related to industrial gas emissions and Continuous Emissions Monitoring Systems (CEMS). We will discuss existing regulations, highlighting recent changes, especially in Brazil. We will also compare the laws of the United States and the European Union, which are global references. Additionally, we will analyze the importance of implementing these systems in Brazil, considering various aspects such as political, economic, and environmental factors. This is a crucial topic for the future of our planet and for ensuring the survival of humanity.

Emissions Control and CEMS: Origin and International Legislation

The history of environmental legislation dates back centuries. An example is a decree in England from the year 1300 A.D., which punished coal burning with the death penalty. However, effective laws on gas emissions emerged later, such as the “Clean Air Act” in the United States in 1956, establishing pollution limits.

In the U.S., EPA’s 40CFR60 is the main regulation for CEMS, while 40CFR75 deals with the “Acid Rain Program”. Other countries, such as Germany, the European Union, the United Kingdom, Canada, Japan, China, and Mexico, also have their own laws for emissions monitoring.

Globally, many countries follow international standards, such as those of the EPA or the EU, in the absence of comprehensive local regulations. International cooperation is crucial to protect the environment.

Brazilian Legislation on CEMS

Brazilian environmental legislation reflects an updated approach, but faces challenges in defining clear regulations between federal and state agencies responsible for regulation and enforcement. Specifically, lack of consensus persists regarding the ideal analysis methodology and standardization of procedures and technologies for Continuous Emissions Monitoring Systems (CEMS).

Environmental laws in Brazil are composed of a complex network of legal instruments, including the Federal Constitution, state constitutions, decrees, ordinary laws, ordinances, and resolutions of local environmental agencies. The main bodies responsible for legislation and enforcement are the National Congress, State Assemblies, Ministry of the Environment (through Ibama and Conama), and State Environmental Secretariats.

The Conama Resolutions 3, 5, and 8, along with Ibama’s Normative Ordinance 348, are the main regulations on gas emissions from stationary sources in Brazil. Additionally, state regulatory agencies such as CETESB, FEAM, FEAMA, CRA, and IAP base their regulations on national technical standards and specific resolutions, both national and international, such as ISO/IEC.

The Public Prosecutor’s Office, both at the state and federal levels, plays an important role in environmental oversight, investigating complaints and initiating legal proceedings against irregularities. Brazil is also a signatory to international treaties, such as the Kyoto Protocol, which aims to control and reduce greenhouse gas emissions.

Many Brazilian companies are already adapting to environmental regulations and seizing business opportunities, such as trading carbon credits. Waste treatment and renewable energy projects are gaining prominence, with companies investing in continuous monitoring technologies to ensure compliance and participate in these lucrative initiatives.

Minimum Constitution for Continuous Emissions Monitoring Systems Regulations – CEMS

Proper regulation for Continuous Emissions Monitoring Systems (CEMS) should encompass various essential aspects to ensure its effectiveness and compliance. Based on comparative analyses of legislation from other countries, we highlight the following elements that should be included in any set of regulatory standards:

Implementation of Rules and Procedures

  • Identification of affected sources.
  • Specification of variables to be measured.
  • Justification for continuous monitoring, including industrial plant control, compliance with emission limits, quantification of emissions for enforcement purposes, and public image.
  • Application examples in different industrial contexts.

Performance Specifications

  • Declaration of technical requirements for installations.
  • Establishment of design specifications.
  • Definition of testing procedures.
  • Accreditation requirements for certifying bodies and periodic independent audits.

Quality Assurance:

  • Quality Audit Manual (QA).
  • Standards and procedures for Quality Control (QC).
  • System audit procedures (QA) and performance measurement.

No regulation will be complete without addressing all of these aspects. Both the United States and European markets have undergone a regulatory development process before arriving at current laws.

In Brazil, there is still confusion regarding customer specifications for CEMS supplies, reflecting the lack of consistency in regulating environmental laws. Applications are treated on a case-by-case basis, leaving end-users vulnerable to suppliers who may not always be qualified.

Despite reports and certificates with quality test results, often regulatory agencies do not consider them valid, requiring additional laboratory analysis. The lack of formal criteria and accredited certifying companies makes it difficult to prove optimal performance.

Some state regulations address these points more comprehensively. However, it would be more efficient to consolidate all these standards into a single national code, accompanied by more capable technical oversight to ensure strict compliance with the law.

Main Stationary Sources of Atmospheric Emissions

The main stationary sources of gas emissions to the atmosphere, according to international environmental agencies and organizations, include the following processes:

  1. Incineration Processes: This covers the incineration of hazardous industrial waste, co-incineration of domestic waste, landfill gases, and hospital or contaminated waste. In Europe, Directive 2000/76/EC specifically addresses waste incineration.
  2. Combustion Processes: This encompasses a variety of equipment and processes such as furnaces, boilers, incinerators, and kilns, whose emissions are regulated to limit atmospheric pollutants, especially in large combustion plants.
  3. Processes Using Solvents: Industrial processes that employ solvents and may emit toxic volatile materials to the atmosphere.
  4. Gas Turbines: Mainly in cogeneration thermal power plants.

The EPA 40CFR60 identifies about 30 different emission sources in its subparts, such as generators burning fossil fuels, petroleum refineries, and pulp and paper mills, specifying the components to be monitored.

Performance Specifications for CEMS

European Standards: European standards, largely based on German legislation, establish measurement principles for various gases and unit systems for variables to be measured. Specifications include:

  • Sulfur dioxide (SO2), nitrogen oxides (NO and NO2), carbon monoxide (CO), and carbon dioxide (CO2), among others.
  • Characteristics such as linearity, cross-sensitivity, pressure and temperature influence, response time, detection limit, and measurement uncertainty.

EPA 40CFR60 Standard: This standard incorporates minimum specifications for the installation of CEMS and determines the performance of gas analyzers and testing procedures. Performance Specifications include opacity measurement, SO2, NOx, CO2, CO, TRS analyzers, mass emission flow monitoring, among others.

These characteristics, required for CEMS certification, are crucial to ensuring the accuracy and reliability of atmospheric emission data collected by continuous monitoring systems.

Regulatory Requirements for Continuous Monitoring System Installation

According to current standards and resolutions, the requirement for continuous or periodic monitoring varies according to the activity and characteristics of each process. However, generally, pollutant monitoring follows a predetermined table, establishing the type of monitoring and its frequency based on the emission rate.

In the case of continuous monitoring, measurements for determination of the result must include the necessary parameters, according to the technology employed and the particularities of each process or equipment, such as effluent temperature, flow rate, humidity, pressure, O2 content, among other relevant operation parameters.

Regardless, the trend is to establish the requirement for continuous monitoring in all processes, regardless of the emission rate and plant characteristics. This aims to facilitate inspection and ensure effective control of the entire process.

Intermittent ContinuousSemestral
Total MP0 – 0,20,2 – 5,2>5,0
SO₂0 – 5,05,0 – 50,0>50,0
NOx0 – 5,05,0 – 30,0>30,0
CO0 – 5,05,0 – 100,0>100
Organic Gaseous Substances
TOC0 – 3,03,0 – 10,0>10,0
CI₂0 – 0,050,05 – 1,0>1,0
Inorganic Gaseous Substances (containing Cl2 – calculated as HCl)
HCI0 – 0,30,3 – 3,0>3,0
F and inorganic gaseous substances (containing F – calculated as HF)
HF0 – 0,050,05 – 0,05>0,05
H₂S and TRS0 – 0,050,05 – 1,0>1,0
Inorganic Gaseous Substances (containing F – calculated as HF)
Hg0 – 0,0010,001 – 0,005>0,005

Final Considerations and Conclusion

Brazilian environmental legislation is constantly evolving, seeking to establish more effective criteria for the control of atmospheric emissions and their continuous monitoring systems.

This evolution is inevitable, driven by the increasing demand from society for a better quality of life and the urgency to preserve the environment for future generations.

Process companies have been investing significantly in anti-pollution equipment and stricter control of combustion processes to meet the requirements imposed by legislation. To ensure the effectiveness of these efforts, it is essential to continuously monitor the performance of these equipment, preferably providing online data to facilitate auditing by environmental agencies and enable efficient plant management.

In this context, Continuous Monitoring Systems (CEMS) play a fundamental role as a management tool, contributing to process improvement, early identification of operational problems, cost reduction, and ensuring acceptable levels of gas emissions into the atmosphere.

Furthermore, compliance with the Kyoto Protocol and opportunities to obtain carbon credits further encourage the adoption of sustainable practices by companies.

It is inevitable that in the coming years there will be a growing demand for online monitoring systems in compliance with these purposes, driven by legal, social, and economic pressures.

Another relevant aspect is the international and internal pressure for companies to obtain ISO 14000 certifications, highlighting the importance of effective environmental management systems to promote harmony between industrial activity and environmental preservation.

Although many laws and regulations still need to be supplemented, regulated, or reformed, it is essential for legislators and environmental agencies to commit to determining standardized methods and procedures as quickly as possible. Otherwise, there is a risk of inadequate projects that do not meet the necessary requirements and generate additional costs for re-adjustments.

Compared to the challenges faced by the United States and the European Union, Brazil has an advantage in being able to learn from their experiences and follow the correct path without repeating the same mistakes, aiming to achieve its goals more efficiently and sustainably.


EPA Standards 40CFR60; 40CFR75; 40CFR65 and their appendices.

ISO Standards 7935; ISO/IEC 17025; BS EN 45001; ISO 6879; ISO 10155; ISO 14164; ISO 9169; ISO 10396; ISO 10849; ISO 12039;

Environmental Legislation – Public Prosecutor’s Office – Environment – State Public Prosecutor’s Office of São Paulo – Official Press – São Paulo 2000.;

CONAMA Resolution Number 8/1990

Guidance on the Acceptance of German type Approval Test Reports for CEMS.

Procedures and General Requirements for the Compliance Testing of Continuous Emission Monitoring Systems – The Environmental Agency’s Monitoring Certification Scheme (MCERTS), Version 2, Revision 1, April 2003 – UK;

Cotta, Michele Karina et al. – Clean Development Mechanism Projects in Brazil – UNICAMP.

Denardi, Estefânia Prezutti Legal aspects of the Kyoto Protocol

ARAÚJO, N. Private International Law. Brazilian Theory and Practice – in accordance with the New Civil Code. Rio de Janeiro: Renew. 2003. p. 27.

DOLINGER, J. Private International Law. General Part. 6th ed. Rio de Janeiro: Renew. 2002.

SOARES, G. F. S. International Environmental Law. Emergencies, Obligations, and Responsibilities. São Paulo: Atlas Editora. 2003.

FRANGETTO, F. W; GAZANI, F. R. Legal Viability of the Clean Development Mechanism (CDM) in Brazil. The Kyoto Protocol and international cooperation. São Paulo: Petrópolis. 2002. p. 57.

BELMIRO, T. R. The Evolution of the Global Carbon Market.


Continuous Emission Monitoring System – CEMS

The ALUTAL / FUJI ELECTRIC Continuous Emission Monitoring System (CEMS) is used to measure real-time emissions of polluting gases from an industrial boiler, cogeneration, power plant, or thermal plant. The CEMS is used to monitor and control compliance with environmental regulations, to monitor plant performance, and to provide data for maintenance planning.

Continuous Emission Monitoring System CEMS

Long-term superior stability continuous emissions monitoring systems

Simultaneous measurement of up to 14 components in combustion gases. The Fuji CEMS Continuous Emission Monitoring System allows continuous monitoring of combustion gas emissions from natural gas, fuel, coal, industrial processes, urban waste combustion, or waste incineration, such as: CO – CO2 – NOX – N2O – NH3 – HCI – CH4 – O2 – H2O