One aspect of understanding comparative risks is understanding how people perceive risks. The nature of a risk often leads to different perceptions of the risk by the people affected. The following discussion is taken from WHO's booklet on risk communication (it covers radio-frequency fields as well as power-frequency).
Surveys have found that the following pairs of characteristics of a situation generally affect risk perception.
Familiar vs Unfamiliar technology
Familiarity with a given technology or a situation helps reduce the level of the perceived risk. The perceived risk increases when the technology or situation, such as EMF, is new, unfamiliar, or hard-to-comprehend. Perception about the level of risk can be significantly increased if there is an incomplete scientific understanding about potential health effects from a particular situation or technology.
Personal control vs Lack of control over a situation
If people do not have any say about installation of power lines and mobile telephone base stations, especially near their homes, schools or play areas, they tend to perceive the risk from such EMF facilities as being high.
Voluntary vs Involuntary exposure
People feel much less at risk when the choice is theirs. Those who do not use mobile telephones may perceive the risk as high from the relatively low RF fields emitted from mobile telephone base stations. However, mobile telephone users generally perceive as low the risk from the much more intense RF fields from their voluntarily chosen handsets.
Dreaded vs Not-dreaded outcomes
Some diseases and health conditions, such as cancer, or severe and lingering pain and disability, are more feared than others. Thus, even a small possibility of cancer, especially in children, from a potential hazard such as EMF exposure receives significant public attention.
Direct vs Indirect benefits
If people are exposed to RF fields from mobile telephone base stations, but do not have a mobile telephone, or if they are exposed to the electric and magnetic fields from a high voltage transmission line that does not provide power to their community, they may not perceive any direct benefit from the installation and are less likely to accept the associated risk.
Fair vs Unfair exposure.
Issues of social justice may be raised because of unfair EMF exposure. For example, if facilities were installed in poor neighbourhoods for economic reasons (e.g. cheaper land), the local community would unfairly bear the potential risks.