Your New Continuous Electronic Radon Monitor: Reading Between the Lines

by Peter C. Foller, Ph.D.


Digital Issue:


Radon is a naturally occurring radioactive gas that unnaturally concentrates in homes.  Indoor/outdoor temperature/pressure differential effects draw the gas into homes from the soil below.  The EPA believes radon causes 21,000 lung cancer deaths per year in the U.S. (the second leading cause behind smoking).  This results in ~$10B/year of excess U.S. health care costs.

EcoQube radon detector

In response, people are increasingly taking a measure of control by purchasing continuous electronic radon monitors (CRMs).  The EcoQube by Ecosense, Inc. is a prime example.  In 2021, it was recognized by both Consumer Electronic Show (CES Innovation Award 2021 Honoree) and TIME (List of 100 Best Inventions of 2021) for raising awareness in the area of health and wellness.  What people see with CRMs is both critically important and intriguing.  Why all the ups and downs in radon levels?

Referring to the accompanying figure, a 90-day look at continuous monitor data from a home teetering on the edge of being hazardous, the variation seen is fairly typical.  Such wild swings can be puzzling.  However, suppliers of CRMs don’t want their customers calling in a radon professional over a 1-day spike.  Some homes only temporarily read high during certain seasons and in certain weather patterns.  Conversely, some high-reading homes temporarily test low.  Understanding long-term multi-seasonal variation through a graphic is important to understanding one’s risk.

radon trend

It is somewhat amazing that we can measure radon at all.  There is so very little of it, yet its consequences can be life altering.  There are only about 1.5 x 105 atoms of radon in a liter of outdoor air.  This compares with 2.5 x 1022 air molecules in a liter of air.  Expressed another way, radon amounts to 1 of every 100 million billion atoms in air.  However, when that one atom decays, it produces a high-energy (i.e. high speed) charged particle, that provides the means by which, in the case of the EcoQube, the device measures a tiny current and infers the presence of radon.  

The apparently erratic signal of a CRM is reflective of many factors.  Some is just the separation of signal from noise inherent in making extremely delicate measurements.  However, variation may be caused by the opening and closing of doors and windows which bring in air from the outdoor environment thus diluting household radon.  Opening the door to a basement may do just the opposite.  Furnace fans, depending on where they are located, may produce similar effects.  Bathroom vent fans depressurize a home too, drawing in air.  However, what is going on outside a home is of more critical importance.  Homes act as chimneys reacting to indoor/outdoor temperature differential producing minute pressure differentials as warmer air rises.

 When radon is trending up, this generally means chimney effects are drawing in fresh radon from the soil underlying your home through cracks and penetrations.  Air expands with temperature, thus slightly lowering its pressure and creating an opportunity for higher-pressure air to intrude.  The further apart warmer indoor conditions and colder outdoor conditions are, the greater the effect.  Lower barometric pressure, for instance in rainstorms, facilitates the escape of radon from the soil underlying one’s house.  From there, the chimney effects of the home above take over.  Conversely, if it is hot outside and air conditioning is running (recirculating indoor air for energy efficiency), household radon may also rise due to the lack of ventilation.  Confusing, yes?  No single effect explains everything.  

radon trend at work

When home radon levels trend down, this generally means chimney effects are not strong.  Indoor and outdoor air temperatures (and thus pressures) may be more in balance, or barometric pressure is steady or rising indicative of nice or clearing weather. In addition, perhaps chimney effects have not been strong enough to reestablish the normal radon levels in your home, allowing some of it to naturally decay in accordance with its 3.8-day half-life (one half of radon present decays and disappears every 3.8 days).

It’s easy to “over think” what is going on.  The important thing is to find a long-term average characteristic of your home and the way you use your home.  Ventilation behavior is important, but overriding factors are more likely to be the geology on which your home sits, its design, and methods of construction.  Geology can be checked versus the EPA’s maps.  Important design factors are whether there is a basement, whether footprint is large, whether there are multiple stories to create stronger chimney effects, and the tightness of the building envelope (often tighter in newer homes for improved energy efficiency).  If your long-term multi-seasonal numbers test high (over the EPA’s 4.0 pCi/L guideline), and reasonable and sustainable ventilation behaviors provide insufficient control, it is well worth calling in a radon professional.

A radon professional may recommend several courses of action that can be staged so that costs of mitigation stay within what is strictly necessary.  Perhaps you only have some cracks and penetrations to seal.  These may be producing well-defined hot spots.  If so, perhaps the more costly installation of vent fans and associated plumbing may not be needed.  

With a CRM comes understanding above and beyond the use of legacy radon detection methods such as one-time-use single-location plastic track detection chips or activated carbon packets which are sent away to a laboratory for analysis.  Take control by choosing a CRM-- perhaps even an EcoQube.  And, if it proves necessary, stay in control by choosing to call in a professional!  


  1. Lung cancer deaths due to radon:
  2. Lifetime costs of lung cancer:
  3. CES 2021 Innovation Award
  4. TIME 100 Best Inventions 2021
  5. EPA Map of Radon Zones
  6. Ecosense, Inc. website: