What are most places that Radon comes from

Is there a possible way to decrease the exposure to Radon and prevent diseases?

Research Paper: requirements & instructions

Perform the research on the subject you posted on the research proposal discussion board. Review my feedback on your proposal and reply to me with any questions. Research on environmental health problems should include scientific evidence supporting the associations between [the environmentally hazardous substances] and [the health effect (diseases)]. To investigate the associations (often aims causal relationships), you will have to explain about appropriate exposures and characteristics of health effects.