It still carries a risk equivalent to smoking 8 cigarettes a day, or 3 times the risk of dying in a car crash. The risk is proportional to the radon concentration. Whatever your current radon level, reduce it to a practical minimum. Pores in concrete draw in water by capillary action. Your basement or slab is by far the single largest source of humidity in your home.
Humidity promotes molds and mildew, dust mites, fungus, bacteria, and other biological contaminants.
Seal your basement or foundation slab to stop soil gas and reduce dampness in your home. Reducing humidity prevents molds, mildew, dust mites, and musty odors. I have a concrete floor and cinderblock walls in my basement. I dropped the radon reading from 18 to 0.7. But after several months, efflorescence pushed it out and it blistered and peeled.