Human health risks and environmental risks are different and are perceived differently; health risks primarily threaten human health, whereas environmental risks threaten both human and environmental health. Nonetheless people tend to view environmental risks as impersonal, primarily threatening nonhuman elements or distant others, making it difficult for risk communicators to motivate target audiences to take risk-mitigating actions.

This dissertation argues that because environmental risks threaten both health and the environment, messages about this category of risk can be framed in either a health or an environmental context as a means of altering risk perceptions. It is further asserted that, all things being equal, message features that are more or less relevant to either the health or the environmental frame will achieve different results depending on which message frame is used. As a means of investigating this claim, two types of similarity (demographic similarity and scene similarity) were manipulated in a 2 (risk frame: health, environmental) × 2 (demographic similarity: high, low) × 2 (scene similarity: high, low) between-subjects experiment (N = 568), in which participants were exposed to a message about drought framed as either a health or an environmental risk. 

The results show that scene similarity interacts with the two message frames (health and environmental) for narrative persuasion and behavior-related variables. Specifically, high (versus low) scene similarity resulted in better persuasive outcomes for the health frame than for the environmental frame, whereas low (versus high) scene similarity resulted in better persuasive outcomes for the environmental frame than for the health frame. Additionally, the study found that framing an environmental risk as a health risk increased behavioral intention and behavioral expectation. Furthermore, high (versus low) personal relevance improved risk perception, narrative persuasion, behavioral intention and expectation, and response efficacy. 

The study has implications for health and environmental risk communication, particularly for impersonal risks that people perceive to be of low personal relevance, and opens up new avenues for research and practice in areas such as climate change communication and entertainment-education. Limitations, implications, and recommendations for replications and extensions are discussed.