Air quality sensor, atmospheric monitor

Measuring air quality is essential for improving human and environmental health. Changes in the natural composition of the air we breathe are common in industrialised societies, where most of the world’s population lives. Action to eliminate or at least minimise the presence of air pollutants in the atmosphere through control and monitoring measures is a priority for achieving well-being in a healthy environment.

The wealth of industrial activity that surrounds us makes our lives easier through its many products. We also rely on fossil-fuelled mobility to get around. But both activities are the main factors behind the significant increase in concentrations of air pollutants, both indoors and outdoors, in recent decades. Similarly, variations in temperature, humidity and atmospheric pressure naturally affect air conditions.

Atmospheric monitoring makes it possible to study the concentrations of pollutants and their trends, and to evaluate these conditions in relation to the limits set by environmental standards to protect the health of the population. Salcido, A., et al. (2019).

As public awareness of the importance of air quality increases, so does the demand for efficient and accurate air quality assessment systems. Air quality sensors are an essential tool for achieving this, both indoors and outdoors.

An air quality sensor is a device designed to measure and record air quality. In doing so, it provides essential data about atmospheric conditions. Sensors provide accurate information that not only helps to identify the components of the air we breathe but also allows us to quantify them and thus take appropriate action to improve the air quality in our homes, workplaces or elsewhere, thereby protecting the environment and human health

There are also certain instruments and methods used to control and improve indoor air quality, such as air purifiers and ventilation systems.

What happens when air quality is poor?

Knowing the state of air pollution means knowing the composition and concentration of the various gases and particles in the atmosphere. These are elements that occur naturally in certain proportions or vary according to weather conditions. They allow all living things to breathe. The point is not just to live, but to enjoy the well-being that comes from living in a healthy environment.

When the original proportions of gases in the atmosphere are altered, this causes various health hazards. The presence of some pollutants in the air contributes to an increased likelihood of developing illnesses such as respiratory disease, cardiovascular disease and cancer.

“Exposure to air pollutants causes negative effects on the health of the population, both directly in the short and long term, and indirectly through their impact on climate change. 92% of the world’s population faces poor air quality on a daily basis and 90% of the world’s cities do not have sufficient regulations to manage this issue.” Represa, S., (2020).

When is air considered polluted? 

Air is considered polluted if the levels of harmful particles, toxic gases or volatile organic compounds exceed the levels set by the World Health Organisation (WHO). This is in addition to the standards set by national governments or common governmental bodies such as the European Commission. 

Its directives and laws set the most stringent air quality parameters and binding targets for reducing emissions of the main air pollutants in the EU, based on the latest scientific studies on the effects of air quality on public health and the environment. 

The Air Quality Index (AQI) measures the pollutants present in the air and their levels, providing valuable information to help prevent the effects on our bodies. It is based on the levels of various pollutants, including particulate matter, sulphur dioxide, nitrogen dioxide, tropospheric ozone and carbon monoxide. The higher the concentration of these chemical elements, the poorer the air quality and the greater the potential impact on health. 

The basic substances that generate more than 90% of air pollution can be summarised mainly in five groups: particulate matter, nitrogen oxides, sulphur oxides and sulphates, carbon oxides and hydrocarbons. Guerrero, A., et al (2011).

How can air quality be measured?

To know if the air is polluted, an accurate and reliable air quality sensor is the perfect ally for our health and well-being. The use of air quality sensors has become a necessity wherever air quality monitoring is required. In turn, air quality should be monitored at the community and household level, as it is indoors where we spend most of our time.

A significant change in the readings taken by the sensors is a reliable indication of a warning situation in terms of particulate matter and harmful gas levels. To complete its operation, the device should be set to measure in real-time to monitor air pollution and detect critical moments.  Air quality monitors must also be accurately balanced to provide a correct estimate of these levels.

Air quality sensors, in turn, have become an indispensable tool for research and consultancy, particularly in areas related to industry and health. Their relevance lies in their ability to provide accurate, real-time data on air quality. This is critical information for developing rigorous research and providing sound advice on how to improve air quality in a given environment.

What is an air quality sensor?

The air quality sensor is a device that measures various parameters simultaneously to assess the purity of the air in a specific environment. This device uses advanced technology to provide accurate measurements of different particles and harmful gases present in the environment.

Some of these devices can also measure temperature, atmospheric pressure, humidity and dew point. By incorporating additional probes, sensors can collect other data such as wind speed and direction. This allows more precise information to be obtained about the behaviour of different pollutants, and how they behave as they move through the air. In this way, it is possible to predict in advance their arrival to nearby populations and even determine the origin of the detected pollutants.

The data collected by the sensor, after further analysis, provides a very accurate profile of the pollutants present and their evolution in the air. This is the right time to make informed decisions to reduce pollutants and improve air quality.

Sensors use a variety of technologies, such as optical, chemical or electrochemical detection, to measure the concentration of specific particles or gases in the air. They can also use methods such as laser light scattering or gravitational sedimentation to estimate the concentration of particles in the air.

Air quality sensors with smart cartridges typically use advanced technologies to accurately detect and measure specific pollutants. Together they provide a complete picture of the air quality in a given environment. These smart cartridges may contain absorbent materials or chemical reagents that interact with pollutants in the air.

As air passes through the cartridge, the sensors react with the pollutants, allowing their concentration to be measured. These sensors are often designed to be accurate, sensitive and selective, which means that they can reliably detect and identify different types of pollutants.

The advantage of Kunak’s patented smart cartridge technology is that it can be easily replaced at the end of its life cycle. This allows measurement accuracy to be maintained over time as they do not have to be sent back to the factory for replacement, thus minimising costs and periods of non-receipt of environmental data. In addition, this technology can be adapted to different environmental conditions or specific measurement needs without incurring high economic costs thanks to its simple replacement system.

Once the sensors collect the data, it is processed and transferred to an application or software for visualisation and analysis. This detailed analysis provides valuable and accurate results that are used to make decisions to effectively improve air quality.

The data analysis software is a critical component of air quality monitors. Each smart cartridge incorporates a customised algorithm into its technology. This ensures that measurements from all cartridges are consistent. It also provides a clear and easy-to-understand indication of the levels of each pollutant of concern. 

Kunak’s air quality sensors are robust, reliable, easy to use and can be adapted to a wide range of environments to analyse urban, natural and industrial activities.

In short, the air quality sensor is an accessible technology for any urban or industrial management entity. It is also an essential tool for monitoring and managing air quality. Its use protects human health and the environment by providing information based on legally permitted levels of pollution, validated by scientific studies.

Reference instruments and equivalents (AQMS)

High data quality
Regulated and certified
One parameter per instrument
High cost
Limited spatial resolution

Sensor-based air quality stations

Accurate data
In-process certification
Several parameters per sensor
High price/performance ratio
High spatial resolution

Low-cost air quality sensors

Very poor data quality
Not regulated
1 – 2 parameters per sensor
Very low cost
High spatial resolution


How to choose the right air quality sensor for my project?

We can classify air quality monitoring stations into three types: reference or equivalent stations (AQMS), professional sensor-based air quality stations and low-cost sensors. 

Our choice depends on the specific monitoring objectives to be achieved and the needs of each project. The simple logistics and low maintenance costs of the professional and low-cost types mean that both can be used in a wide variety of situations and projects. The difference lies in the level of accuracy and reliability of the data required for each. 

Official or reference stations usually provide continuous measurements at specific locations, which is very useful for long-term monitoring and comparison of data over time. They are able to analyse the presence of multiple pollutants simultaneously. At the same time, they can record meteorological parameters and provide the most accurate measurements. 

The problem with these is their limited spatio-temporal representation and their high installation and maintenance costs.

At the other end of the spectrum are low-cost sensors for personal exposure monitoring and measurement. These are suitable when measurements need to be taken at multiple locations. These systems offer high flexibility as they are highly portable, have very low acquisition costs and require very little maintenance. Such stations are often used for temporary individual exposure assessments, such as in epidemiological studies. They are also used to raise awareness of the quality of the air that everyone breathes.

The problem with this technology is that the measurements are of questionable accuracy and the intra-model variability is high, making it difficult to base important decisions on this data. At Kunak, we always recommend that this type of measurement should be combined with another reliable data source to compare and contrast the measurements made in the study.

Finally, there are the professional sensor-based stations, which are halfway between reference and low-cost sensors.

These air quality stations are the ideal complement to reference stations. They provide larger and more reliable spatial coverage for effective air quality management with high data reliability and accuracy. They also provide real-time indicative measurements that are immediately sent in real-time to an external platform such as air quality software or a third-party platform, allowing the data to be accessed and visualised for further analysis and use. 

These stations can also record meteorological parameters, as they can incorporate different probes to collect other environmental data to complete the detailed measurement of air quality. 

Their cost-effectiveness and low maintenance make them key tools for accurate air quality analysis at hyper-local scales, as well as for use in areas where reference data sources are not available (e.g. developing countries or industries far from urban areas).