The US radon problem, policy, program and industry: achievements, challenges and strategies.

US radon research, policy and programs have stalled since their start in the late 1980s and early 1990s. In 2005, more homes had radon above the US Environmental Protection Agency (EPA) Reference Level than anytime in history since more homes were added to the housing stock that had indoor radon concentrations exceeding 150 Bq m(-3) than had been mitigated. Funding for the US radon program has declined two-thirds from 1997 to 2007. Despite impressive goals for radon reduction, EPA lacks sound progress indicators especially in new construction radon control systems. School radon reduction has been at a standstill since the early 1990s. There has been no significant radon risk reduction in low-income sectors of the population. There is need for effective partnerships between the public and private sectors of the US radon professional communities as well as with the international programs and professionals.