Improving the ventilation of the dwelling and avoiding the transport of radon from the basement, or ground, into living areas; Installing crawlspace or basement ventilation systems; Installing sub-slab depressurization radon mitigation systems, which vacuum radon from under slab-on-grade foundations; Installing sub-membrane depressurization radon mitigation systems, which vacuum radon from under a membrane that covers the ground used in crawlspace foundations; Installing a radon sump system in the basement; Sealing floors and walls (not a stand-alone solution); and Installing a positive pressurization or positive supply ventilation system.