air-Q Radon — patented technology for measuring radon
Radon releases radioactive particles known as alpha radiation. This dangerous noble gas is the second most common cause of lung cancer, after smoking. It rises from the ground or building sites, can even pass through the walls of homes, and is imperceptible to the human senses. With the new air-Q Radon, you can detect this radioactive gas in your home, your house, and your workplace. In addition, the air-Q Radon supports up to 10 additional sensors and functions as a smart air quality monitor.
Buy air-Q radon
What is radon?
Radon is a naturally occurring radioactive noble gas produced by the decay of uranium in the soil. It is colorless, odorless, and tasteless, and can enter indoor spaces through gaps in buildings (such as cracks in the foundation). There are two relevant isotopes of radon—radon-222 and radon-220 (thoron)—both of which are detected by the air-Q Radon measurement module.
Radon can accumulate, especially in poorly ventilated basements. Prolonged exposure to high levels of radon increases the risk of developing lung cancer.
EU directives set the legal limit at 300 Bq/m³, while the WHO sets it at 100 Bq/m³. In general, the less exposure to radon, the better.
1. Patented air-Q Radon module
During the decay of radon, alpha radiation (α particles) is emitted. This radiation consists of helium nuclei (2 protons, 2 neutrons) and has a very short range (a few centimeters in air), but a high ionizing power.
After several years of development, we succeeded in creating our own radon measurement module. Here, radon is quantified by detecting light pulses from a scintillator. Alpha particles are then detected indirectly through their interaction with the scintillator, which generates flashes of light when struck by ionizing radiation; these flashes are counted and thus measured. The scintillator is housed in a measurement chamber that is permeable to gases but opaque to light. The light flashes are detected by a modern, highly sensitive photon sensor called a SiPM (Silicon Photomultiplier), capable of detecting even single photons. The number of light flashes (equivalent to radon decay events) per unit of time indicates the radon concentration and is converted to becquerels per cubic meter. The radon module developed has a patent application pending (EP23176915.9 / 4 471 462).
2. Calibration of the radon measurement module
Our radon modules are individually calibrated at our factory using measurement devices verified in accordance with DAkkS (Deutsche Akkreditierungsstelle, the German accreditation body) specifications in a calibration laboratory (Sarad). The calibration standards were tested and calibrated at 300, 3,000, and 30,000 Bq/m³. All air-Q units undergo a complete measurement cycle lasting several days and are assigned individual calibration values for sensitivity and baseline. The testing is conducted according to strict, standardized procedures to ensure accuracy, repeatability, and linearity.
3. Challenges in Radon Measurement
a. Measurement speed and accuracy versus sensor size
One becquerel is equivalent to one radioactive decay event per second. The standard unit of measurement is the becquerel per cubic meter; thus, the German Federal Office for Radiation Protection (Bundesamt für Strahlenschutz) sets a limit value of 300 Bq/m³. Generally, radon detectors must be considerably more compact—even portable—so that measurements can be taken in a volume much smaller than 1 cubic meter (a cube measuring 1 x 1 x 1 meter), for example, 200 cm³ (0.0002 m³). If one wishes to measure using a sensor with a small measurement chamber, the response time, measurement resolution, and accuracy decrease accordingly. The challenge lies in developing a measurement chamber or measurement procedure that enables high-quality, comparable real-time measurements. For this reason, we opted for a relatively large measurement chamber in the air-Q Radon. In addition, the measurement module operates with optimized passive ventilation of the measurement chamber, enabling it to provide measurement values in a relatively short time that also respond quickly to environmental conditions such as ventilation.
To illustrate how many decays per unit volume should be detected, we have provided a summary here. Thus, 50 Bq/m³ is equivalent to 3,000 radioactive decays per cubic meter, but only 0.6 decays per minute.
Radioactive decays per unit volume and per minute
Radon concentration | Disintegrations per 1 m³ per minute | Disintegration at 200 cm³ per minute |
|---|---|---|
50 Bq/m³ | 3.000 | 0,6 |
100 Bq/m³ | 6.000 | 1,2 |
300 Bq/m³ | 18.000 | 3,6 |
1,000 Bq/m³ | 60.000 | 12 |
b. Averaging algorithm required for measurements in small volumes
Radioactive decays are statistical processes. Therefore, there is a certain probability that a decay event will occur. With low radon exposure, a single radioactive decay more or less within a small measurement volume can result in the measured value being doubled or halved (and thus a possible overestimation or underestimation of the actual radon exposure). For this reason, an averaging mechanism is necessary to obtain a continuous measurement curve. At the same time, averaging results in reduced responsiveness. This is why a sophisticated mechanism is required. An adapted Kalman filter was used for the air-Q Radon.
The air-Q's Kalman filter helps calculate the most accurate estimates possible based on just a few measurement points. It combines past values and trends with current measured values. Each new measurement is used to improve the previous estimate. The filter operates in a stepwise manner and continuously updates its estimate with each new piece of information.
c. Radon and thoron measurement
Most radon detectors are designed/calibrated for radon-222. It is the most common radon isotope and, in practice, the greatest health hazard.
Building materials that may contain thorium can emit thoron (radon-220). These include, for example, clay plaster, pumice, natural gypsum, tuff, and fly ash cement. Thoron is released at the surface and, due to its short half-life (55 seconds), decays extremely quickly. Therefore, during that time, it can only travel a few centimeters away from the material and is detectable only in the immediate vicinity of the aforementioned building materials. The air-Q Radon measuring device cannot distinguish between radon-222 and radon-220; both are displayed as the measured value “radon.”
Certified Quality
The WELL standard is an international rating system for building certification, developed and regulated by the International Well Building Institute (IWBI) in the U.S. It is the first standard of its kind focused exclusively on the health and well-being of people in buildings, setting high standards to that end. The air-Q meets the high requirements set by WELL for air quality measurement and is certified by the IWBI.
Our partners in sensor development
Together with many partners, we developed the air-Q air quality monitor and the air-Q app to improve people’s health and performance. Our development partners are especially important; we work with them every day to create new solutions for healthy, mindful breathing and living.
