Improperly Installed Radon Systems
My only concern is with ACTIVE systems that are improperly installed, unless a passive would be set up so badly that it could cause a health risk. Photos on the page demonstrate improper and dangerous radon system installations.
Although I no longer install passive systems in existing homes (only new construction), I have installed a few where the vent pipe is routed out to ground level. These systems are set up so they could be made into active if needed some day. But, venting a sump pit or slab at ground level poses no health concerns because there would be almost no concentration coming out of the pipe.
The reason I no longer install passive systems in existing homes is that they just don't work, and for a few extra dollars you can rid the home of Radon, and hopefully reduce the moisture in the basement. Radon is pushed up from ground pressures and sucked up from the vaccuum of a home. If a pipe is routed to the sump pit or slab and vented to the outside, there is a chance that it might increase Radon levels. Why? Because if it's windy outside and air is pushed into the vent pipe, more pressure can be exerted under the slab, thereby increasing the amount of Radon in the home.
Most improper systems have the Radon fan in the basement or some other livable space in the house. This is a huge problem, and totally against EPA standards. It's easier to install a system like this, and it will get rid of the Radon in the basement. But what if the fan had an undetectable leak on the exhaust side, one you couldn't hear? This is called mining Radon. The home would not have just a little more Radon, but could have hundreds of Pico curies. How would you like to be exposed to that? Remember the EPA wants homes to be below 4 pCi/L, and if possible below
2 pCi/L.
Another huge problem is to vent an active system at ground level or less than 10 feet from grade. Most of these systems also have the fan in the basement. Studies have shown that re-entry is a serious risk. If a window would be opened, or if someone is in that area they could be exposed to very high concentrations.
Even if the vent pipe is at 10 feet from grade, it might not be right. I have seen homes where the vent is
10 feet off the ground, but there is a window within 10 feet of it, or even right above it on a second floor. Re-entry could still happen in this case.
The photo on the right illustrates one type of improper venting of a Radon system. This set-up is dangerous because Radon gas would be vented directly over the head of anyone standing on the deck.