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Information on Radon Gas Testing

How is Radon Gas Measured ? 

  • Radon gas is typically measured with a "radioactivity" (alpha particle) detector appropriately placed in your house or building.
  • The best time to detect radon gas is in the fall-winter-early spring months when houses are closed up more and radon levels are highest, although a radon gas test can be performed anytime.
  • Normal "short-term" (ST) detection
    • time lines are usually from 2 to 9 days (using traditional charcoal, charcoal liquid scintillation, alpha trak or E-perm detectors, with laboratory analysis)
  • I use a "short-term integrated reading" (2-9 days) with Continuous Radon Monitor (RadStar RS 300i) or Rad Elec E-Perm system for the following:
  •        immediate radon gas levels with analytical report
  •        real estate transactions (co-located detectors)
  •        Tarion New Home Warranty preliminary test
  •         school or public buildings follow up testing
  •          post-mitigation level confirmation
  •  Short-term (ST) readings fluctuate widely and are only indicative of levels at a particular point in              time and should not be used for predicting annual levels or for mitigation decisions.
  • requires "closed house" conditions for 12 hours preceding and during test periods
  • I  perform a "short-term integrated reading"  using the Rad-elec E-Perm system for these measurements
  • I can also use the Landauer Rapidos Alpha Track detector for 10-30 day measurements, however the report takes at least 3-4 weeks to generate due to detector analysis in the USA. 
  • "long-term" (LT) reading (91-365 days) is the most commonly used test
  •  recommended by Health Canada, Middlesex-London Public Health Department, et al
  •        this provides:
  •         better accuracy; daily and seasonal fluctuations are minimized
  •         better reflects annual radon gas levels
  •         for mitigation (remedial action) determination, for Tarion confirmatory tests
  •         requires normal house living conditions during the test
    • I use the Rad-Elect E-perm system or alpha track detector (Accustar AT-100 RadTrak, Landauer Radtrak2) for long term measurements. Any short-term reading above the Health Canada limit (200 Bq/m3), should be followed up by a longer term test. Mitigation decisions MUST be based upon long-term test results. Radon levels fluctuate daily and the long term testing procedures are designed to average the results over the test period.                                                                           


Canadian Society of

Safety Engineering

(CSSE) 2014-2015

Canadian National Radon Proficiency Program (C-NRPP)


American Association of Radon

Scientists and Technologists


Canadian Association of Radon

Scientists and Technologists


Why select me?

As an educator at both the college and secondary school levels, I have been involved in various aspects of health and safety training and education for over 35 years. My formal education involves :

  • Hon. B.Sc Microbiology (UWO)
  • M.Sc. Phytopathology (UWO)
  • B.Ed. Education ( Brock University),
  • College Certificate - Occupational Health and Safety (Fanshawe College)
  • numerous health and safety certifications
  • Radon gas measurement and analysis certification (C-NRPP) (Canadian - National Radon Proficiency Program); C-NRPP has strict protocols and guidelines which must be followed for accurate measurements. In order to maintain my certification, the following must be done each year:
  • CE (Continuing Education) to enhance my knowledge and training,
  • a strict Quality Assurance (QAP) Program must be submitted and followed
  • instruments must be calibrated and cross -checked, and
  • undergo device performance testing in Ohio or Colorado Springs to prove that I am competent in measuring, interpreting and analyzing the data.
  • C-NRPP No. CRT 201319

I have a true passion for health and safety and sincerely believe in the importance of radon gas detection at an affordable price.

I AM NOT INVOLVED IN RADON MITIGATION so I do not have a vested or financial interest in removing the radon or convincing you that you need a radon mitigation system - only in detecting it. There is a C-NRPP-Certified mitigation contractor in SW Ontario that I recommend that will facilitate mitigation and will give you a free estimate if needed.


J.Ainsley Marshall



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