Answer to Question #8976 Submitted to "Ask the Experts"
The following question was answered by an expert in the appropriate field:
While there are numerous radon monitoring systems for performing short-term screening measurements, as well as long-term average concentration measurements, there are relatively few that meet your requirement of being able to provide an estimated value within a very short time, possibly none within the seconds that you specify. None of the manufacturer/model citations below should be interpreted as an endorsement of any particular product.
It sounds as if you are probably not a professional who is doing measurements as a service. If this is so, you may find that any of the systems that would be useful to you may be more expensive than you can justify, but you can make that decision.
Some systems are described as real-time or continuous monitors, but they often require a minimum of one hour, and often longer, before producing a first legitimate reading. Examples of this type are the Sun Nuclear Model 1027, the Femto-Tech CRM-510LP, the Rad Elec E-Perm, and the Safe Home Products Safety Siren 3. The latter device is very inexpensive but requires about four hours before the first reading is acceptable.
Systems that provide a faster response generally require rather sophisticated sampling and measurement technology, and these often come with a commensurately higher price. Pylon makes monitors and detectors that do provide quite rapid readings, such as the AB-5 monitor that may be used with a number of different detector types; one of the most common for sniffing-type applications is the flow-through Lucas–type scintillation cell such as the 110A, 200A, and 300A models. Another example of the “sniffer" type system is available through Durridge Company; the RAD7 instrument provides for both continuous monitoring and “sniffer" modes. The Alpha Guard system from Genitron uses an ionization chamber and has energy spectral capabilities and provides short-term assessment measurements (minimum response time of one minute) in addition to longer-term continuous monitoring. Keep in mind that all of the monitoring systems, even those designed for sniffing purposes to evaluate inleakage of radon, require some integration time, often several minutes, to obtain enough counts to allow meaningful output.
You may wish to speak to some of the manufacturers to inquire whether they make or could make a device to fit your needs, but obtaining readings within a few seconds may not be possible. Good luck.
George Chabot, PhD, CHP