January is National Radon Action Month, and it's a good time to test your home for the dangerous and odorless gas. Radon gas levels soar during the winter months because we keep our windows closed and spend more time indoors. Approximately 1 in 15 homes across the country have high levels of radon, which is the number one cause of lung cancer in nonsmokers. At-home tests are easy to find at any home improvement store. Once you know your levels, you can find easy ways to remedy the situation.