Communication of urban heat island risks

Abstract

Urban areas are usually warmer than their surrounding areas; this phenomenon is called the urban heat island (UHI) effect. This effect causes a higher exposure to heat and increases the risk of heat-related adverse health effects. To show the urgency for adaptive measures to reduce the UHI, risk communication can help. However, communication of health risks is a difficult task. Scientists mostly determine risks based on expected annual mortality (probability of occurrence and effect). However, the perception of risk is not solely based on statistical analysis; other factors are also important. Sandman called these other factors, collectively, ‘outrage’; the expected annual mortality was called ‘hazard’. He introduced in 1987 a new definition of a risk: Risk = hazard + outrage There are several outrage factors (benefit, voluntariness, dread, control, origin, etc.) that contribute to our perception of a risk. These factors are no misperceptions of risk; they are intrinsic elements of our meaning of risk and explain why we worry more about a risks than another risk. The UHI risk is a risk for a population. Managing risks for populations differs from managing risks for individuals. Risk managers judge risky activities not only based on health risks but to a large concept of health, social, financial and economical risks and benefits. These elements determine to a certain degree the tolerability of risk. The willingness-to-pay to reduce a risk is dependent on the tolerability of that risk. To communicate UHI risks, it is necessary to (1) give an objective overview of the risk. Additional, one should try to (2) define how society perceives the risk. To influence this perception, one can make the outrage factors of UHI more outrageous. This will affect the tolerability of a risk which can in turn enhance the willingness-to-pay to reduce the risk. Eventually, (3) the risk communicator should analyse him/herself to understand how he/she is perceived by the audience.