Health messages that linguistically assign agency to a threat (e.g., HIV infects people) tend to evoke more fear and elevate perceptions of threat severity and susceptibility relative to those that assign agency to humans (e.g., people contract HIV). The present experiment (N = 843) extended these findings to a nonliving health threat, radon gas, and compared nonsentient (e.g., radon gas is seeping . . .) and sentient (e.g., radon gas is invading . . .) threat agency language. Sentient threat agency language elevated perceptions of threat severity compared to both nonsentient threat and human agency language, which did not differ from each other. Furthermore, sentient threat agency language evoked more fear than nonsentient agency language when the advocated recommendations were moderately (but not completely) effective.