Normal carbon dioxide concentration detected by a CO2 sensor in a school

Top 5 CO2 sensors in 2023

Carbon dioxide is a gas produced naturally when we breathe. Proportional to the number of people living in a house or room, CO2 does not pose a health risk unless the concentration is high. High levels of carbon dioxide are often linked to poor air circulation. Knowing the level of carbon dioxide therefore helps to know when to ventilate a room.

Moreover, airing at the right time helps to limit the transmission of viruses while avoiding over-ventilation of our living spaces. According to Florence Elias (professor of physics at the University of Paris), when faced with Covid-19, it is advisable to air a room as soon as the CO2 exceeds 800 ppm, if everyone is wearing a mask, or as soon as 600 ppm if no mask is worn.

Our selection for the year 2023

There are many CO sensors on the market. In order to make your choice easier, we have limited our selection to 5 products that we believe are the best for your home in 2023.

1. CO2 detector Aranet4 Home

The most efficient

The Aranet4 Home CO2 detector is equipped with an NDIR infrared sensor that can accurately test the level of CO2 in the air. This CE-approved sensor is practical and easy to carry, and is very robust thanks to its polycarbonate design. The quality of its E-Ink digital display is also appreciated, which gives it a 360° HD view of the characters displayed.

Finally, in addition to being connected to your Smartphone (Android and iPhone), this product offers a clean and intuitive interface. You will have no difficulty in visualising the evolution of the measured parameters (CO2, humidity and atmospheric pressure).

2. Curconsa CO2 detector

Our favourite

The Curconsa CO2 detector is a device with an NDIR infrared sensor capable of accurately testing the concentration of carbon dioxide in the ambient air. Equipped with a thermometer and hygrometer function, this detector provides real-time information on the level of CO2 in the air with a measurement range of 0 to 5,000 ppm.

The CE-approved product has a humanised design with two types of visual warning for a more intuitive reading of the air quality, namely a three-colour LED light and a smiley face avatar. Equipped with a rechargeable lithium battery, the Curconsa has a standby time of 18 hours. We like that it's light and easy to carry around: whether you're on the move, in the office or at home, this is our favourite CO2 detector.

3. Selensy CO2 detector

The best value for money

The Selensy CO2 detector is a device with an infrared NDIR sensor. This CE-approved device measures the amount of carbon dioxide in the air, the relative humidity and the ambient temperature in real time. The Selensy is light and easy to carry. It will easily accompany you wherever you go, whether at work, in a bar, at the office, at school, etc.

Equipped with an LCD screen, this detector displays the level of carbon dioxide over a range of 400 to 5,000 ppm and gives an alarm as soon as the CO2 level reaches a concentration of 1,000 ppm. It has a colour-coded air quality display: red for poor, yellow for normal and green for good. Equipped with a 5V micro-USB port, this product is rechargeable and warns you when the battery is low.

4. Curconsa CO2 detector

The most suitable for office and school

The Curconsa CO2 detector is a stationary type device, ideal for the school or office. Using a dual-channel NDIR sensor, it detects CO2 while preventing cross-contamination of carbon dioxide with other gases. This gives it greater accuracy and a longer life span (up to 15 years). The product is CE approved and displays the CO2 level in the air in real time, as well as the humidity level, room temperature and time.

Equipped with a TFT screen with touch control, the Curconsa also has a built-in light sensor that allows it to automatically adapt its backlighting according to the ambient light. Finally, in addition to its ability to store the last 7 days of data, it is also possible to set an audible alarm as required (over a range of 400 to 4500 ppm CO2).

5. Netatmo CO2 detector

The design bonus

The Netatmo CO2 detector is a device equipped with an infrared NDIR sensor. Practical and intelligent, it tells you what setting to adjust to create a healthy environment for you, your baby or an asthmatic person. The Netatmo is highly accurate and can detect carbon dioxide over a measurement range of 0 to 5,000 ppm with an accuracy of +/- 50 ppm (0 to 1,000 ppm) and +/- 5 % (1,000 to 5,000 ppm). It also records the relative humidity, temperature and noise level of your home.

CE approved, this product is mains operated and does not have an LCD display, however, you can view the data and monitor your home's indoor atmosphere by connecting to your smartphone wherever you are. Simple and stylish, you can also tap the top of the CO2 sensor to light up and keep you informed about your indoor air quality.

What is a CO2 sensor?

Carbon dioxide (CO2) is a colourless, tasteless, odourless gas and essential to life on Earth. Unlike carbon monoxide (CO), CO2 is non-toxic unless its concentration in the air becomes too high.

How to choose it?

Currently, the best performing sensors on the market are non-dispersive infrared (NDIR) carbon dioxide sensors, whether for their longevity, reliability, sensitivity or cost. The reasons for this choice are as follows:

  • NDIR sensors generally last 10 to 15 years longer than their counterparts (phoacoustic, chemical or estimated).
  • Other sensors may have a cross-sensitivity bias to water vapour, etc., unlike NDIR sensors.
  • Chemical sensors need to be regularly recalibrated, unlike NDIR sensors.
  • NDIR sensors require very little maintenance, are easy to install and are cheaper than other types of sensors.

Is it mandatory?

Unlike smoke detectors, carbon dioxide detectors are not mandatory at the time of writing (28/10/21). However, air quality monitoring with a CO2 detector is a subject of increasing debate, especially for our schools...

As part of the fight against Covid-19 (and any other virus), it is advisable to renew the indoor air regularly. The use of a CO2 detector can help determine when the air in an enclosed space needs to be renewed.

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Where to install it?

A CO2 detector can be placed anywhere in your home. It can even accompany you in every room or when you are out and about. We advise you to place it in an open area within sight. This way you can easily see a reliable measure of the air quality around you.

Is CO2 hazardous to health?

CO2, also known as carbon dioxide or carbon dioxide, is a natural gas and is harmless to health in small quantities. It is ubiquitous in our lives and is used to carbonate our drinks, extinguish fires, freeze food, and has various uses in agricultural and medical applications.

An abnormal concentration of this gas can have harmful effects on our health. These may include headaches, dizziness, difficulty breathing, sensations, tingling or pins and needles, restlessness, sweating, fatigue, increased blood pressure, increased heart rate, coma, asphyxiation and convulsions.

The scale below helps to understand the impact of CO2 on our health:

CO2 levelImpact on health
400 ppmAverage level in outdoor air
400 - 1000 ppmTypical level found in occupied spaces.
600 - 800 ppm Recommended level of ventilation in a room to limit the transmission of Covid-19.
1000 - 2000 ppmLevel associated with complaints of drowsiness and poor air quality.
2,000 - 5,000 ppmLevels associated with drowsiness, headaches, and stagnant, stale, stuffy air. Poor concentration, increased heart rate, loss of attention and mild nausea may also be present.
5,000 ppmThis level is potentially toxic and can lead to oxygen deprivation.
40,000 ppmThis level is lethal due to oxygen deprivation.

What is the role of carbon dioxide?

Carbon dioxide is an important greenhouse gas that helps trap heat in our atmosphere. Without it, the Earth would be a cold and inhospitable planet. However, its gradual increase in the Earth's atmosphere is contributing to global warming and disrupting our planet's climate.

How is CO2 produced?

Carbon dioxide is a greenhouse gas produced by the decomposition of organic matter, off-gassing from volcanoes, forest fires. It also has its source in human activities (man-made) emissions such as the burning of fossil fuels, the clearing of forests, the draining of wetlands...

Carbon dioxide is the main contributor to global warming and is responsible for the acidification of the oceans because it is not destroyed in the atmosphere: it leaves the atmosphere to be found elsewhere (biomass, soil, oceans, etc.).

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How does a CO2 detector work?

A CO2 sensor is an instrument that measures the level of carbon dioxide in the air. There are 4 types of sensors for measuring carbon dioxide.

Non-dispersive infrared (NDIR) CO2 sensors

NDIR sensors use the light spectrum to detect carbon dioxide. They consist of an infrared source, a light tube, an interference filter (wavelength) and an infrared detector. By pumping gas into the light tube, the electronics measure the absorption of the light's own wavelength and determine the level of CO2 in the air.

Photoacoustic sensors

Photoacoustic sensors measure the level of CO2 in the air by subjecting a sample to pulses of electromagnetic energy specifically tuned to the absorption wavelength of CO2. With each pulse of energy, the CO2 molecules absorb and generate pressure waves by photoacoustic effect. These waves are then detected by an acoustic detector and converted into a CO2 measurement.

Chemical CO2 sensors

Chemical CO2 sensors use polymer or heteropolysiloxane layers to measure CO2 in the ambient air. They are relatively small and their main advantage is that they consume very little energy. However, their lifetime is rather short and they show short and long term drift effects. These sensors need to be calibrated over time to maintain a reliable CO2 measurement over the long term.

Estimated CO2 sensors

Estimated CO2 sensors are based on an estimation of the amount of volatile organic compounds (VOCs) and hydrogen gas (H2) available in the ambient air. This equivalence is particularly suitable for indoor environments where the main source of CO2 is human respiration (gyms, offices). However, these sensors are not reliable in the presence of CO2 sources other than respiration.