Test for radon - for peace of mind
RADON IS NOT AN INSIGNIFICANT THREAT IN THIS PART OF THEWORLD. The gas that can’t be detected by eye or nose is a killer — it’s responsible for about 21,000 lung cancer deaths nationwide every year, with nearly 3,000 of those in people who have never smoked. And the incidence of danger-level radon in Northern New Mexico is four times the national average.
“In our area, one in three homes that are tested have radon levels that pose a significant health risk, meaning over 4.0 picocuries,” said Steve Burke of Clean Sweep Environmental Soluitions. “That’s the limit at which the EPA would like to see mitigation occur.”
The U.S. Environmental Protection Agency estimates that one in every 15 American homes has radon levels at or above 4.0 pCi per liter. Taos, Santa Fe, and Los Alamos counties all have shown a much higher incidence. Burke says it’s because of the region’s high-desert geology.
Radon’s health hazard comes from the radioactive particles that are emitted as radon gas, and which is produced by the decay of naturally occurring uranium. Those particles can be inhaled into the lung and bombard your cells with dangerous, cancer-causing radiation.
The only way to determine if a home or building has elevated indoor radon is to test it, according to the New Mexico Environment Department, and you can do that yourself. Test kits are available for less than $30 at Home Depot and Lowe’s, as well as through Alpha Energy Laboratories, www.doctorhomeair.com.
“We do radon testing for real-estate transactions as well as radon mitigation,” said Burke, partner with Paul DeDomenico in the Clean Sweep business. About seven years ago, they added radon to their 1977 company’s roster of services, which also includes mold detection and mitigation, chimney cleaning, and water-damage solutions.
Home radon testing requires a minimum of 48 hours. During the testing, windows and doors must remain closed (other than for normal entry and exit) and fans must be turned off in the room where the radon monitor is located.
If your house tests over 4.0 pCi/liter, it is recommended that you perform, or hire a company such as Clean Sweep to perform, a second test. If high levels of radon are confirmed, it’s time to address the problem, for example with sub-slab depressurization. Radon in an existing house can be mitigated by having the concrete slab penetrated at one or more locations and an outside fan installed to create a negative pressure below the slab.
Due to a pressure difference, soil gases move through holes in your foundation, your slab, or the floor over your crawlspace, said Santa Fe architect and homebuilder Bob Kreger. Integrating a passive sub-slab ventilation system to control soil gas migration creates a thin air zone of negative pressure under the slab. Integrating a properly installed “air barrier” (a plastic membrane) over the passive radon collection area is fundamental in isolating radon from your living space.
A vent pipe connects the sub-slab ventilation system to the exterior through a roof vent.
Radon mitigation systems can typically be installed for $1,500 to $3,000. Adding a heat recovery ventilation (HRV) system also can also help by diluting any indoor radon.
If no radon-prevention is built into a foundation, the danger is no less real in a newhouse. Nor does the type of foundation matter. The best way to avoid contact with radon is in a new house that has built-in prevention. “What I do is very inexpensive,” Kreger said. “It’s generically referred to as flat pipe, which is a Mira Drain dimple membrane that you lay under the slab.
“The old way of using four inches of crushed rock and perforated pipe is unnecessary. Both systems simply enable unobstructed collection of the radon gas to pipe risers that go through the roof.
“The flat pipe is two feet wide and it goes around the perimeter and maybe a few runs across the slab, depending on the square footage, and that will get covered with rigid foam, then they pour concrete.”
Kreger said the flat pipe was originally designed as a product for releasing hydrostatic pressure on the vertical surface of a foundation. It allows the water from the ground to run down through the dimples and into a drain. “But when you turn the dimple membrane horizontally, it works to allow radon gas to be vented.
“We vent passively. We don’t put in a fan unless an inspector upon resale finds radon. I’ve done all the hard work in the construction, then at that point they can just add an inline fan and plug it in.”
For more information about radon and prevention and mitigation alternatives, see cleansweepnm.com, env. nm.gov/nmrcb/radon.html, and epa.gov/radon.
CONSTRUCTION ALTERNATIVES A newer way to install passive sub-slab radon ventilation: the black “flat pipe” (left) is an easier solution than the old, but still valid, crushed rock with perforated pipe (below left).
Below, a variation using both flat pipe and crushed rock under the air barrier