Insight Home & Building Inspections, LLC. 
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Radon Gas

Insight Home & Building Inspections, LLC. Will gladly test for Radon gas in your home. The following information will try to answer questions you have in regards to radioactive Radon Gas. Please visit the links page on our website that will direct you to a government website provided by the EPA for Radon Gas. Some of the information below was taken from the government radon site. This site is a wealth of information to help you make an informed decision. Unfortunately for us, Wisconsin is an area known for Radon intrusion into our homes.

What is Radon?

Radon is a gaseous radioactive element having the symbol Rn, the atomic number 86, an atomic weight of 222, a melting point of -71ºC, a boiling point of -62ºC, and (depending on the source, there are between 20 and 25 isotopes of radon - 20 cited in the chemical summary, 25 listed in the table of isotopes); it is an extremely toxic, colorless gas; it can be condensed to a transparent liquid and to an opaque, glowing solid; it is derived from the radioactive decay of radium and is used in cancer treatment, as a tracer in leak detection, and in radiography. (From the word radium, the substance from which it is derived.) Sources: Condensed Chemical Dictionary, and Handbook of Chemistry and Physics, 69th ed., CRC Press, Boca Raton, FL, 1988

Sources of Radon are the Earth and rock beneath the home, well water, and some building materials.

OK, now that we have satisfied all of you science geeks let's try an easier explanation:

Radon is a colorless, odorless soil gas that comes from the natural disintegration of radioactive heavy metals uranium and thorium below the earth's surface. Radioactive decay actually makes life on Earth possible by heating its core.

How does it get into our homes?

The air pressure inside homes is slightly lower than in the ground (typically 0.7-1.4 psi vacuum), which draws in radon gas from several feet away. Combustion appliances, like furnaces, water heaters, and fireplaces, as well as exhaust fans and vents, reduce the indoor air pressure. The warm air inside our homes naturally rises reducing the air pressure on lower floors. Strong winds can even create a vacuum. When the ground is frozen or soaked by rain, "bottled up" radon gas in the ground moves to the warm porous gravel and disturbed ground around the house, then up into the house.

The majority of homes whether, a slab or a basement are built on concrete which is extremely hard and porous. The naturally rising Radon gas is pulled into the house by the negative vacuum and in through openings or cracks and through the pores in concrete. Modern houses tend to build up radon, because the building envelope is almost airtight while the foundation is "leaky" to soil gas. The soil gas infiltration ranges from less than 1% to over 20% of the total "fresh air" infiltration into homes.

The heavy radon gas will usually accumulate in basements and on lower floors. Heating and air-conditioning, natural air movement, and diffusion of radon atoms through the floors and walls distribute radon throughout the house.

What is Safe?

Before we can answer the question "What is safe?" we must know how Radon is measured. Let's begin by asking the question: What are "picoCuries"(pronounced pi"ko-ku´re)?

The concentration of radon gas is not measured directly but rather by the radioactivity it produces. This radioactivity is expressed in picoCuries per liter of air, or "pCi/L". A Curie is a unit of radioactivity equivalent to 1 gram of radium and the prefix "pico" means a trillionth. In an average basement, 38 million atoms will undergo radioactive decay each hour.

SO, WHAT IS SAFE? PER THE EPA: "There is No Safe Radon Level!"

The U.S. Congress studied the risk to public health and set the "target" radon level for homes (The "Radon Act") as an outdoor level. Then, considering the high cost of fan radon mitigation, the US EPA issued more relaxed guidelines for homeowners:

Radon Guidelines for Homeowners
0.4 pCi/L is the "target" level for homes (The U.S. Congress)
2 pCi/L EPA's "consider action" limit - consider fixing your home!
4 pCi/L EPA's "action" limit - fix your home!

It is difficult for people to accept that their home, a place that one looks to for security, is hiding invisible danger. Yet, the average person receives a higher radiation dose from radon at home than from all other natural or man-made sources combined.

Outdoor radon levels in the U.S. range from 0.02 to 0.75 pCi/L (picoCuries per liter), averaging 0.4 pCi/L. But homes draw concentrated radon gas from the ground. Because radon is nine times heavier than air, elevated radon levels generally build up in basements and on lower floors. Although the U.S. Congress has set the natural radon concentration outdoors as the target level for homes, approximately two thirds of homes exceed it. A half of American homes have a radon level above 0.67 pCi/L (the median level). The average (mean) radon level in US homes is 1.25 pCi/L, or three times higher than the average level outdoors.

Nearly 8 million US homes, or 1 out of every 15, have radon levels above the EPA's 4 pCi/L "action" limit and nearly 1 out of 6 exceed the EPA's 2 pCi/L "consider action" limit. You should always try to reduce radon to a practical minimum - if you just settle for 4 pCi/L, your home will be more radioactive than 94% of US homes. The cancer risk is proportional to the radon level. Always reduce your radon level to a practical minimum! Reducing radon from your current level by 50% (or 80%) lowers the cancer risk to each member of your family by 50% (or 80%).

Health Effects

Radon is the number one cause of lung cancer among non smokers

Radon is the number one cause of lung cancer among non-smokers, according to EPA estimates. Overall, radon is the second leading cause of lung cancer. Radon is responsible for about 21,000 lung cancer deaths every year. About 2,900 of these deaths occur among people who have never smoked. On January 13, 2005, Dr. Richard H. Carmona, the U.S. Surgeon General, issued a national health advisory on radon.

Visit for more on a study by Dr. William Field on radon-related lung cancer in women and to read a press release by the surgeon General.

How does Insight Home & Building Inspections test for Radon in my home?

Insight Home & Building Inspections is pleased to announce that we use Sun Nuclear digital radon testing machines to test for Radon. The model 1027 continuous radon monitor is a patented electronic detection device used for the measurement of radon gas. Model 1027 is intelligently designed to be fully programmable by the inspector.

For accurate radon test readings, it is necessary that the house be closed up (windows and doors) for 12 hours before the inspection and 48 hours during the inspection. These conditions are as follows:

• Keep windows closed.
• Doors should not be opened except for normal entrance and exit.
• Any system which would bring outside air into the house should not be operated
• Large volume air exhaust systems should not be operated.

Heating and air conditioning may be operated normally. And, it is acceptable practice to operate the clothes dryer, range hood, and bathroom fan during the period of testing.

The testing device is programmed to shut down after 48 hours of testing and results can be obtained immediately from the equipment. A report can be provided on site if the request is made prior to the inspection/test otherwise results can be emailed within hours of the test.

How do I get rid of the Radon in my home?

To reduce the Radon levels in your home we use a term called "mitigation". There are several ways that radon can be reduced and many companies that offer them.

Two key ideas are to either use vacuum to redirect the gases above the roofline or to seal the floor thereby reducing the porosity in the concrete. Both would reduce the effects the but the best and most common radon mitigation technique is called either soil depressurization, or active sub slab depressurization (ASD), or sub slab suction (SSD). This is by far the most common type of radon reduction system installed today. Generally, a hole is drilled through the basement slab, a cavity is excavated beneath the slab, and 3" or 4" diameter PVC pipe is run up from the slab, out through the basement wall, where it connects to an exterior mounted exhaust fan. From the fan, an exhaust pipe runs up at least 10 feet above ground level, and 10 feet from any windows.

The EPA has mitigation standards on their website

Unfortunately, each home, like people, is an individual and may be difficult to perform either method. If your levels are above what is considered acceptable, do some research in your area, the Internet is a great tool, and obtains several quotes from qualified contractors. As always we will be happy to answer any questions for you. Insight Home & Building Inspections does not profess to know everything however, if we don't know the answer we will find out!! 

Radon System Installed Radon System Diagram