Phone +34 985 73 39 52


How to measure air pollution

Published on 30 January, 2019

Pollution and outdoor air quality,

Air pollution is a serious problem. This is at least stated by the WHO (World Health Organization), which has included this issue among the 10 main threats on the planet for the year 2019. But how to measure air pollution? Minimizing the health and socioeconomic consequences of the poor air quality that the population suffers in many places will lead to a radical change in the behavior of citizens. But it will also be essential to develop policies and adopt measures considered unpopular by broad sectors of the population.

However, these decisions must be based on data, so monitoring and knowing the concentration of different pollutants should be a priority.

How to monitor air quality

The quality of the air analyzes the amount of pollutants in the atmosphere. This monitoring is essential to:

  • Evaluate the impacts on public health and provide information to the population.
  • Determine if an area meets regulatory standards.
  • Evaluate changes in air quality as a result of the state of the implementation plans, making the necessary adjustments to achieve better air quality in the future.

The strategies for carrying out this analysis include both direct measurements from fixed or mobile air quality stations, notification from the sources themselves (industrial facilities or traffic) or models that can consider various sources of information (traffic levels, industry, mobile apps, low cost sensors, satellites such as those included in the Copernicus program, etc.) along with climate considerations, topography and dissipation patterns.

How does an air quality sensor work?

At this point, it is necessary to mention the operation of the sensors that monitor the quality of the air. There are multiple sensors for measuring gases, differing from each other according to:

  • Sensitivity levels.
  • Type of gas to be monitored.
  • Combustible gases (carbon dioxide and methane, for example) are usually monitored via catalytic and infrared sensors, while for the detection of toxic gases the use of electrochemical and metal oxide semiconductor sensors (also known as MOS) is common.
  • Physical dimensions.

Its form of operation varies depending on the type (semiconductor, infrared, ultrasonic, electrochemical or catalytic sensors), but basically you can distinguish two large groups: devices that function by absorption, contact with gas and chemical reactions, and sensors whose operation It is based on infrared or ultrasonic emissions.

Which are the main pollutants monitored?

The main pollutants monitored, as well as their concentration, are usually determined by current legislation. This legal basis is used to create the so-called Air Quality Indices (AQI). Each country establishes its respective scales, therefore there are different measurement and warning systems, an aspect that up to a certain point makes it difficult to establish a global policy to combat pollution.

The following image shows, for example, the disparity between the recommendations of WHO and those in force in the European Union.

how to measure air pollution

Source: Air pollution: Our health still insufficiently protected. Special Report of the European Court of Auditors. @ European Union, 2018.

The most harmful pollutants

However, there is some consensus on which the most harmful pollutants are, and which require special attention:

  • Nitrogen oxides (NOx): they are produced as a result of combustion at high temperature, with traffic being one of the main sources of generation. Its effects on health are noticed through inflammation of the airways, organ disorders, such as liver or spleen, or systems, such as the circulatory system or the immune system.
  • Ozone (O3): ozone is formed in the atmosphere by the reaction between nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the presence of heat and sunlight. It can lead to respiratory problems and can contribute to increasing premature mortality.
  • Sulfur dioxide (SO2): produced by burning fuels with high sulfur and petroleum content. The main sources are industrial processes and the extraction of metals from minerals. It can have harmful effects on health even at great distances from the source and may cause respiratory problems, protein metabolism, headache or anxiety.
  • Particulate matter in suspension (PM10 and PM2.5): they are, together with the oxides of nitrogen, the most harmful pollutants. Due to their small size, they penetrate to the deepest part of the respiratory system and can even reach the blood flow. The thickest particles (PM10) usually have a natural origin and are composed of dust, dirt, pollen, mold, spores and other materials. The finer particles, on the other hand, are generated by the use of gasoline and diesel vehicles, the combustion of fuels for power generation and industrial processes.

These pollutants not only have a detrimental effect on human health, but the environment is also affected, damaging the growth of crops and forests, damaging buildings or causing problems such as acid rain.

Also, different scientific publications advocate monitoring other pollutants that have been proved to be harmful to the environment, such as ammonia that negatively affects the Earth, or have a special contribution to climate change, such as escaping methane gas.

Benefits obtained thanks to the monitoring of air pollution

The continuous monitoring of air pollution, as it has been pointed out in this article, provides information to administrations and people about the quality of air, allowing the analysis of compliance with standards and the adoption of measures aimed at minimizing the harmful effects of contamination, which becomes especially visible when analyzing the number of medical consultations or lost work hours. However, air pollution also has other lesser-known effects. Thus, for example, two recent studies associate pollution with unhappiness (Zheng et al., 2019) and sleep problems (Billings et al., 2018), two aspects directly related to health or labor productivity. And although monitoring pollution does not automatically mean an improvement in these aspects, it provides valuable information that can improve the quality of life of the population. In short, the measurement of pollution represents a fundamental aspect to improve air quality. Because, as William Thomson claimed, “what is not defined cannot be measured. What is not measured cannot be improved. What is not improved, always degrades.».

ENVIRA  is a company with a long career in the monitoring, operation and maintenance of air quality networks, which offers comprehensive solutions with the latest technology and has an accredited reference laboratory to ensure maximum accuracy in all measurements.


  • Ubilla, C., and Yohannessen, K. (2017). Air pollution: effects on respiratory health in the child. Las Condes Medical Journal, 28 (1), 111-118.
  • Billings, M., Gold, D., Szpiro, A., Aaron, C., Jorgensen, N., Gassett, A., Leary, P., Kaufman, J. and Redline, S. (2019). The Association of ambient air pollution with sleep apnea: the multi-ethnic study of atherosclerosis. Annals of the American Thoracic Society.
  • Zheng, S., Wang, J., Sun, C., Zhang, X., and Kahn, M. (2019). Air pollution diminishes the happiness expressed by Chinese citizens in social networks. Nature of human behavior.
How to measure air pollution

Do you want to know more about Envira?

Contact us