Ten facts about RADON: **

  1. Radon gas is noble & heaviest gas on periodic table.

** **2. Radon is the largest source of exposure to radioactivity.

****3. Alpha particles are emitted from the decay of radon gas;
the impact of the discharge of alpha particles is what
damages lung tissues, not the gas itself.

****4. Alpha particles are very light- they have a helium nucleus.

****5. Radon is not limited to the basement, the forces that draw it in to the
home will continue to draw it up into living areas.

****6. The SURGEON GENERAL , on Jan 13, 2005 issued a
health advisory : RADON CAUSES LUNG CANCER

****7. Radon gas is a class A Carcinogen ( group 1)

**** 8. Radon is spontaneous and unpredictable

****9. Uranium decay chain leads to Radon which decays
to Polonium, lead, bismuth, and polonium again;
the half lives are relatively short- increasing
potential for exposure to radioactivity.

**10. Radon mitigation (reduction) systems CAN also
help reduce mold and other volatile organic
compound gasses, and have been installed
for those purposes.

All depends upon the home, placement, weather conditions, etc. I hope you do not state all of those in every inspection report. Have you taken the iNACHI radon course? If not, I highly suggest it.

Well thanks I will take the course, I’m sure it is great, but i happen to already hold a state license in Radon measurement, and just completed a new CE course on the physics of Radon.

Here is another fact:
An** improperly** installed mitigation system can actually INCREASE radon gas entry in to the home.

Life is learning

Dog gone it Joe! You just reminded me I need to get some CEU’s?:stuck_out_tongue:
Good information and some quite powerful as well.

Gary, on your site it states that homes on crawl spaces that are properly vented do not need tested for radon (I see where this would dilute the radon), yet in the same paragraph it states to close off the ventilation when temps are under 25 degrees. Wouldn’t you need it tested if your closing off the ventilation?

Radon tests are mostly all taken in basement, under-ground areas, which are the lowest available living areas of a home. If you have a bedroom, office, exercise room or family room below ground level, a radon test is strongly suggested. Homes with crawl spaces generally do not need radon testing*, but under home spaces should be properly vented**. Check crawl space vents to be sure they are open at all sides of the foundation during spring, summer, and fall seasons. Crawl space access doors should be screened during these seasons for proper cross ventilation. Close crawl space vents when outside air temperatures fall below 25 degrees.*

The comment that homes with properly vented crawlspaces do not need radon testing, is very misleading. Just because the crawlspace is well vented, doesn’t mean the home doesn’t need mitigation. The home could still have elevated levels, just as a home built in a flood plain on elevated piers could have elevated levels. Radon doesn’t get in just through the floor, it can come in through pipes, electrical conduits, an even be brought into the home… Granted, it’s not nearly as great a risk in a home like this, but it is still a risk. According the the EPA and NEHA NRPP The only way to know for sure is to test the home, and then re-test every other year.

I test crawl spaces.

I test homes with crawl spaces. According to accepted protocols (US EPA, NEHA NRPP) you are to test in the lowest habitable level of the home. That’s either the first floor, or the basement if there is one.

Just a note:
We have found elevated radon levels in hundreds of high rise condos up to the 27th floor. Many have open parking garages under them.
Last year the EPA gave Florida a grant to study the elevated radon levels in Collier and Lee county high rises (Southwest Florida).
Every time you think a certain structure shouldn’t have elevated radon you get surprised.

You’re not supposed to according to the EPA. Click the link below and see the box to the right.


I don’t know where you came up with that information. The EPA states “ALL” homes at the 3rd level or below should be tested.


Illinois Administrative Rule (partial)

a) Measurement Location

  1. Short-term or long-term measurements shall be made in each lowest structural area suitable for occupancy. For example, a split-level building with a basement, a slab-on-grade room and a room over crawlspace shall have measurements made in each of the foundation types: the basement, a slab-on-grade room and a room over the crawlspace.

A) Measurements shall be made in rooms that can be regularly occupied by individuals, such as family rooms, living rooms, dens, playrooms and bedrooms.

B) Charcoal canisters of any type shall not be placed in bathrooms, kitchens, laundry rooms, spa rooms or other areas of high humidity.

C) Radon in air measurements shall be made either concurrently with or prior to any diagnostic radon in water measurements.

D) Measurement devices shall be:

i) Undisturbed during the measurement period;

ii) At least 3 feet from doors, windows to the outside, or ventilation ducts and out of the direct flow of air from the ventilation duct;

iii) At least 1 foot from exterior walls;

iv) 20 inches to 6 feet from the floor;

v) At least 4 inches away from other objects horizontally or vertically above the detector;

vi) At least 4 feet from heat, fireplaces and furnaces, out of direct sunlight, etc.

E) Measurement devices may be suspended in the general breathing zone and, if suspended, shall be 20 inches to 6 feet above the floor.

F) Measurements made in closets, cupboards, sumps, crawlspaces or nooks within the foundation shall not be used as a representative measurement and shall not be the basis for a decision to, or not to, mitigate the radon level within a building.

I agree, this was on Gary’s Site Here

LOL! The EPA has a great track record so far. They just follow on behind learning from what the industry is doing.

A 27 story building can have 125 “homes” in it. the EPA does not say not to test a building above the 3rd floor.

Great point Doug! There was never any clear EPA guidance to discourage radon testing above the 3rd floor, but it was never encouraged either. The high rise radon problem was known for years, but was just a “Florida” thing. Guess what, it isn’t.

Take a concrete box (a condo) with no air leakage (i.e., hurricane-resistant, energy efficient, and keeps the humid summer air outside) and let a little radon leak out of the concrete with no dilution possibilities. What do you get? Hmmm, high radon with no soil contact. How would one find this scenario? I would say a radon test in order.

If you look for something, you will be surprised where it can be found. Keep up the good work Doug!

Shawn Price


Let’s not all forget Radon in water being released into the home.

1 year warranty inspection.

Radon piping runs behind garage door header.


Radon monitors should not be placed in a crawl space. Homes with crawl spaces should be tested at the lowest living space.

…each lowest** structural area suitable for occupancy**.

BUT…maybe testing a 3rd level condo unit would make sense if it had a shared HVAC system for entire building AND the hvac equipment is in basement, because the “take up” air would be coming from basement area which potentially could have high levels of radon gas. Just a thought.