I ran a short term 3 day test and a long term 128 day test in my basement. Got a reading of 3.9 from both tests. EPA says 4 or above, fix it. If between 2 and 4, consider fixing it. Our last house had a mitigation system (basically a 24x7 fan venting out of the ground under our basement). I'm going to get a quote. The risk is described as "7 out of a 1000 non-smoking people might get lung cancer" at 4.0 level.

    sdandrea1 My house is prepped for it which basically means I have a 4" piece of PVC coming up from the slab. I assume that I could buy an inline fan and vent it outside. I think it's referred to as sub slab ventilation.
    Amazon sells them.

        sdandrea1 I looked at this hard before I sold, my readings were lower than yours. Plus Fairfax and Fredericksburg is rated low. All said, pumps are low cost and if you already a sump pump installed, they simply parallel the lines out.

        I would not install for myself but if I had Grands, easy to get a pump installed.

        https://www.epa.gov/sites/default/files/2015-02/documents/r3-va-riskmap-largefont.pdf

          sdandrea1

          Our reading in SC Pa was higher and we had the system installed. Wasn’t cheap. Our installer gave us a ten year warranty but went OB and we had to replace the fan part after the real 5 year warranty ran out. 🙄. Did the work myself after ordering the fan part. Nice system.

            LBlack14 Radon gas seeps from the ground into houses typically from a basement. Causes lung cancer.

            Once into the air, essentially harmless

                backinit

                Our house would be an ez install. Sump pump is near an exterior basement wall with an electrical outlet right there. We paid $1500 last time.

                    sdandrea1 I you have an existing sump pump well and a dry basement I would agree. This is much like a fan forced dryer vent below the floor.

                      The recommendation up here is above 200bec/m3 which equates to 5.4 pic/litre.
                      So our action level is higher than yours.
                      Interesting.

                        When we sold our house in Haverhill MA in 2002 the Radon test came back above the limit. Had to have a fan installed in the basement. Cost ~ $1000 dollars.

                        raggmann54 I remember seeing this elaborate air exchange system that my sister had installed in her first house. I'm not going to say anything negative about radon, but I will say it seems to be more of an issue in the last 30 years....as houses have become tighter. Nearly every building product in your house is emitting formaltihyd or some other harmful chemical compound. The regulations on those have gotten tighter as well...all the way to the inside of the building membranes.

                          We had the "sub slab depressurization system".....I think that was the name?.... put in our first house and it was already in the next house. I have no doubt some company made some good $$ in this area when homeowners could have just installed a cheap fan. Better safe than sorry?

                            Read this awhile back so I'm going by memory but if you have your house tested you must supply that information if you sell. So if you're on the cusp as someone said 3.9 with 4.0 being actionable and you don't fix it, you must make the buyer aware. If you don't they can come after you later. Something like that.
                            Also have heard just opening the basement windows if you have them is enough.