WHERE DOES RADON COME FROM?
Radon comes from the natural radioactive decay of radium and uranium found in the soil beneath the house. The amount of radon in the soil depends on complex soil chemistry, that varies from one house to the next. Radon levels in the soil range from a few hundred to several thousands of pCi/L. The amount of radon that escapes from the soil to enter the house depends on the weather, soil porosity, soil moisture, and the suction within the house.
HOW DOES RADON GET INTO THE HOUSE?
Houses act like large chimneys. As the air in the house warms, it rises to leak out the attic openings and around the upper floor windows. This creates a small suction at the lowest level of the house, pulling the radon out of the soil and into the house. You can test this on a cold day by opening a top floor window an inch. You will notice warm air from the house rushing out that opening; yet, if you open a basement window an inch, you will feel the cold outside air rushing in. This suction is what pulls the radon out of the soil and into the house. You might think caulking the cracks and the openings in the basement floor will stop the radon from entering the house. However, scientific studies show, it only takes enough unsealed cracks or pin holes in the caulking to equal a hole 1/2" in diameter to let all the radon in. It is unlikely that caulking the accessible cracks and joints will permanently seal the openings radon needs to enter the house. The radon levels will still likely remain unchanged.
Fortunately, there are other extremely effective means of keeping radon out of your home. Throughout the country, several million people have already tested for radon. Some houses tested as high as 2,000-3,000 pCi/L; yet, there hasn't been one house that could not mitigate to an acceptable level. Mitigation usually costs between $500-$1500.
WHAT IS THE RISK OF RADON EXPOSURE?
Scientists believe radon exposure is the second leading cause of lung cancer. When radon decays, it shoots off alpha particles. These are small, heavy, electrically charged, sub-atomic particles consisting of two protons and two neutrons. If an alpha particle strikes the chromosomes in a lung cell, it could alter the way that cell reproduces. Our bodies immune system should recognize and destroy these mutant cells before they can multiply over the next 10 to 20 years into a recognizable cancerous growth.
Some peoples immune system is better than others. Because of these inherent differences, radon doesn't affect everyone the same.
HOW SERIOUS A RISK IS RADON?
According to the following EPA radon risk chart, radon is a serious health problem.
If 1,000 people were exposed to this level over a life time who are:
Annual
Radon Level....Smokers.............Never Smokers
20 pCi/L....14% or135 people.....0.8% or 8 people could get lung cancer
10 pCi/L.....7% or 71 people.....0.4% or 4 people could get lung cancer
4 pCi/L......3% or 29 people.....0.2% or 2 people could get lung cancer
2 pCi/L......2% or 15 people.....0.1% or 1 person could get lung cancer
DO SCIENTISTS AGREE THAT RADON IS DANGEROUS TO BREATHE?
There is little disagreement that breathing the hundreds of pCi/L of radon that caused thousands of uranium miners to get fatal lung cancer is definitely harmful. Many scientists disagree with the EPA about what the level of radon should be before it should be reduced.
The EPA studied the lung cancer risk of uranium miners exposed to 400 pCi/L. They assume the risk of a home owner exposed to 4 pCi/L to be one hundredth as much. Based on this assumption, the EPA guideline level of 4 pCi/L represents a much greater risk than allowed for other environmental pollutants.
Other scientists have tested more than 70,000 homes across the United States. This study shows the counties with the highest average radon levels had the lowest incidence of cancer. Perhaps, breathing the low levels of radon found in the home environment, might not be harmful. Neither study fully accounts for all the different confounding factors that can cause cancer. The truth probably lies somewhere between these two theories.
WHAT IF, I DECIDE TO REDUCE THE RADON LEVELS IN MY HOME?
If you feel the radon levels are high enough to justify installing a radon mitigation system, we recommend installing a good quality, durable, energy efficient system. All our radon reports testing above 4 pCi/L, include detailed specifications, describing the installation and materials needed to achieve this. It is best to have all mitigation contractors bid on installing the system exactly as specified in this report. All too often the sellers or their agents end up deciding, who will do the work, and how it will be done. Their main concern is that it be installed as cheaply as possible to get the radon levels down below 4 pCi/L for the retest. Often they have the contractor who installed the system, do the retesting to verify it is below 4 pCi/L, before he gets paid. This could create a possible conflict of interest.
WHAT SHOULD I LOOK FOR IN A PROPERLY INSTALLED SYSTEM?
* A... Install all fans outside the living area of the house, so all interior piping is under negative pressure. Many contractors find it cheaper and easier to put the fan in the basement near an existing electrical outlet. Often these fans and piping develop leaks. This could allow the system to start pulling the thousands of pCi/L of radon out of the ground and blow it into the basement or crawlspace; thus making the radon levels in the house higher than they where originally.
* B... The high radon concentration air blowing from the fan should discharge above the roof, or at least ten feet from any doors, windows or decks. No one wants to breathe hundreds or thousands of pCi/L coming from these fans.
* C... Dig the suction pit under the floor as large as possible, or make sure it intersects the void beneath a grade-beam foundation.
* D... Seal crawlspaces with a gas membrane, made of cross-laminated polyethylene, placed between two layers of 30 lb. tar paper, to protect it from damage. Make sure the membrane is tightly fastened to the foundation walls, with plywood strips and sealed with industrial grade urethane caulking. It is cheaper to install one layer of regular polyethylene directly over the soil, and fasten it to the walls with duct tape, glue or caulking. This method will reduce the radon levels, but the single layer of regular polyethylene gets torn when someone crawls across it. Duct tape or glue usually falls off the wall within a month or so. When this happens, the system will still keep the radon levels down, but the fan will start pulling large amounts of heated air out of the house. The added cold air could subject the crawlspace plumbing to freezing and increase the cost of heating your home as much as $200.00 to $300.00 a year. This unnecessary loss of heat could add up to $20,000.00 to $30,000.00 over the hundred year life of the house. The money saved on the initial
installation might not be such a bargain after all.
* E... Caulk the large cracks and joints in the concrete floor slab to prevent unnecessary heat loss.
* F... Install a manometer or warning device to alert you if anything goes wrong with the system.
* G... Permanently label all systems, with the contractors name, phone number, operation and maintenance instructions and a place to note all radon test results. The people living in the house 15 to 75 years from now will need to know what this system is, and why it is needed.