Simple Guide:

Despite the various operational choices when using the Sniffer, it is possible to use the Sniffer by following this series of simple steps:

  • Start the Sniffer in clean air
  • Measure areas expected to have low radon concentration making sure to leave the Sniffer running as you work your way up to higher concentration
  • The Sniffer will start up in “Short” (15 second average) mode. Use this mode when measuring high or unstable radon concentrations where there will be sudden increases or decreases
  • On the face of the sniffer there is a single button. Use this to active the “Long” mode (5 minute average) when measuring low and stable radon concentrations where there will be little changes
  • Run the Sniffer in clean air at the end of the day

An additional resource for simple instructions for successful use of the Sniffer is the Radon Sniffer Quick Start Guide


Principle of Operation:

Once powered on, the CT007-R uses an internal pump to draw air through a scintillation cell. Before air is drawn into the scintillation cell, any radon decay product in the air is removed by a filter. As radon decays inside the cell, the alpha particle emitted hits the wall of the cell, which is coated with scintillation powder, the Silicon Photomultiplier (SiPM) detects the scintillation light and converts it into an electronic pulse, which is then counted. The radon concentration in the air is calculated every 3 seconds. Every time a pulse is counted, the “Counts” LED indicator will flash. Once you plug in the charger, the “Charging” LED turns on if it is not fully charged. If it is fully charged with the charger plugged in, the “Charged” LED will turn on instead. The Sniffer can be used as a stand alone unit or in conjunction with a smartphone.


When using the CT007-R as a stand alone unit, less features and modes of operation are available. In stand-alone operation, the Radon Sniffer runs using our “Smart” algorithm, which is explained below. Users can press the button to toggle views of the radon activity concentrations either in the 15 second, the 5 minute, or the overall run time average, to know which response time to operate in, read below. When stand-alone, the sniffer is only able to operate sniffing mode, which is further explained below. 

Paired with a Smartphone:

When connected to a smartphone, the Sniffer itself will behave in the same manner as if it was being operated as a stand-alone unit. The Radon Sniffer app has additional options for operation. In the app, users now have the ability to have the data calculated using the “Standard” algorithm as opposed to the “Smart” algorithm that the unit operates on. The two algorithms are explained below. Also available when paired with a smartphone, are an additional mode, timer. This is briefly explained below and further on the Radon Sniffer app page, which also outlines additional features the app offers. Below is a chart that compares the two modes of operation.



Paired with smartphone

Smart Mode



Standard Mode












*This chart only compares the algorithm and the operating modes, there is an abundance of additional features that are only accessible via the app.

Smart and Standard Mode:

When radon decays into decay products, they plate out and stick to the side of the wall. They continue to cause counts for a few hours after a high radon exposure. Due to this many radon measurement instruments need a long time to recover from exposure.

The ‘Smart’ algorithm seeks to calculate the radon decay product contribution to the counts and compensate for it. This mode is explained further in the ‘CT007-R Radon Sniffer Principle of Operation’ video below.

The ‘Standard’ mode simply assumes that one third of all counts received are due to radon decay products and does not try to compensate for the build up of radon decay products. This makes it not as efficient in measuring high radon levels. 

The differences between the two modes are explained in the ‘CT007-R Radon Sniffer Companion App’ video below at minute 8:48 to 10:21. The Radon Sniffer itself is always in ‘Smart’ mode. The display on the app can switch between the two modes.

Sniffer Vs. Timer


Sniffer is when the CT007-R measures the radon activity concentration either in the 15 second, the 5 minute, or the overall run time average. When viewing sniffing mode on the app, the “Raw Counts” are also displayed, as well with the option to toggle between units. 


Timer allows users to measure the total counts in a specified period. Timer mode is independent of sniffer mode they will run simultaneously. This mode is only available when connected to the app. To learn how to access this mode, see the Radon Sniffer App page. 



Different Response Times:

While in sniffer mode, the CT007-R measures the radon activity concentration either in the 15 second, the 5 minute, or the overall run time average. This gives users the opportunity to choose the response time best suited for their needs. In the simplest terms, use the “Short” mode (15 second average) when measuring high or unstable radon concentrations where there will be sudden increases or decrease and the “Long” mode (5 minute average) when measuring low and stable radon concentrations.

This is because the Sniffer works based on a sampling principle so that 1 radioactive decay within 15 sec corresponds to approximately 340 Bq/m3 or 9 pCi/L. These radioactive decays are what we refer to as counts. In concentrations below 340 Bq/m3 or 9 pCi/L, sometimes there will be no counts within a 15 second interval because radon decays irregularly. The sniffer will show “0”, which corresponds to no decays detected in the last 15 seconds. Sometimes, it will show around 340 Bq/m3 or 9 pCi/L, which corresponds to 1 decay detected in the last 15 seconds. It could also detect 2 or 3 counts in 15 seconds and display 700 and 1000 Bq/m3 or 18 and 27 pCi/L. The short sampling interval of only 15 sec may lead to jagged readings at low radon concentrations. The 15 second scale should only be used when you are in high levels. Since radioactive decay is random, you need to count long enough to get a statistically significant number of counts. To get reasonably stable readings, you have to wait long enough to count at least about 10 alpha particles (that gives you about a 30-40% statistical error). To achieve this, the following integration/counting times are needed:

Rn-222-concentration of 30 Bq/m3 or 1 pCi/L: Approx. 30 min.
Rn-222-concentration of 150 Bq/m3 or 4 pCi/L: Approx. 5 min.
Rn-222-concentration of 3400 Bq/m3 or 90 pCi/L: Approx. 15 sec.

While more stable, when measuring using the long response time, it is harder to detect changes in radon concentration. Therefore, when using the Sniffer to source radon entry points and hot spots, use the “Short” mode.

Additional Rescources:

User Manuals:

Quick Start Guide:


For any other operation concerns you can contact us.