What year was radon identified as a significant health risk by research studies?

Radon was identified as a significant health risk through extensive research conducted primarily in the 1970s. This was when studies began to highlight its link to lung cancer, particularly among miners who were exposed to high levels of radon gas in enclosed environments. By the 1980s, awareness had started spreading widely, leading to increased public health initiatives and regulatory measures aimed at controlling radon exposure in homes and other buildings. It was during this decade that significant public health campaigns and research efforts to mitigate radon in residential settings were intensified, but the initial identification of radon as a significant health risk was established earlier in the 1970s. Thus, the most accurate answer is the 1970s, recognizing the foundational research that laid the groundwork for understanding radon's hazards.