Radon being radioactive gas has adverse impacts on human health. In recent decades, radon gas has been listed as a human carcinogen sincethe massive effect of radon gas associated with lung cancer is widely recognized.Moreover, the health effects of indoor air pollution, with radon being one of the major contributors is aseriousconcern. The radon gas exposure limits are mainly obtained by various epidemiological and toxicological studies. Accordingly, different surveys conducted in particular parts of the world. Considering the harmful effects of radon gas on human life, quantitative researches are carried onto emphasize the importance of monitoring indoor radon gas levels. One of the main goal is to accommodate more accurate estimation for protection from the risks of long-term exposures to radon gas in the indoor environment. In this paper, the recent status of radon gas and its contributions to indoor air pollution aresummarized. Results of the comprehensive review demonstrate that, however treat of radon gas exposure as an air pollutant is being raised overtime, the knowledge and awareness of the impacts of these exposures in different situations still need more investigations. In case of encountering radon gas problems, specialists should be consulted toutilize appropriate radon testing and mitigation techniques. Studies are still being conducted to clarify certain discrepancies with the aim of providing consistent results and informationon the impacts of radon gas on environment and human health.