Communicating includes sending and receiving messages. Effective communicators take time to learn the values, attitudes, beliefs, and preferences of their intended audiences. By understanding who makes up the audience, a communicator can develop messages that resonate with the audience, motivating them to take action. For public health emergency risk communicators this means creating messages that educate and motivate people to protect their health during an emergency. This chapter explains how to identify audiences through audience segmentation by identifying risk variables such as age, health status, and geographic location. Stakeholder management theory provides critical insights into how to work and communicate with partners, stakeholders, and the public during a health emergency. Key information about public health laws including libel, slander, HIPPA and Right to Know is included, analyzing how public health laws impact emergency risk communication. Descriptions of public health powers for state and local health departments are included. A student case study analyzes the Jackson, Mississippi, Water Crisis using the Crisis and Emergency Risk Communication framework. Reflection questions are included at the end of the chapter.

The first 24–48 hours of a health emergency require the responding health agency to communicate with the public about what they know, what they don’t know, and what they are doing to find new information. By engaging in initial messages early in a crisis, health agencies can demonstrate credibility and build trust with the public. This chapter deconstructs initial messages and identifies four critical message components: addressing uncertainty, expressing empathy, making a commitment, and providing messages of self-efficacy. By delivering initial messages early and often a health agency can demonstrate the Crisis and Emergency Risk Communication (CERC) principles of Be First, Be Right, Be Credible, Show Respect, Express Empathy, and Promote Action. The chapter provides practical steps on how to write initial messages and provides quick response communication planning and implementation steps such as identifying communication objectives, audiences, key messages, and channels and developing communication products/materials. This chapter also includes key tips related to spokespeople, partner agecies, and call centers regarding ensuring message consistency during an emergency response. Uncertainty reduction theory is highlighted. A student case study analyzes the Flint Water Crisis using the CERC framework. Reflection questions are included at the end of the chapter.

The COVID-19 pandemic impacted individuals worldwide, regardless of their geographic location, religious or political beliefs, occupation, or social standing. People’s experiences were directly impacted by lockdown measures, physical distancing, masks, vaccine recommendations, or illness of self or friend or family member, as well as by how their local and national elected officials and public health leaders managed and communicated about the pandemic. As people went into lockdown, they went online and found a proliferation of information both true and false about the pandemic. The constant deluge of online information, the new and evolving outbreak, and the worldwide impact created a complex health emergency.  The COVID-19 pandemic brought emergency risk communication to the forefront of every health agency in the United States, from city to county to state to federal levels of government. This chapter provides an overview of public health preparedness; explains how Crisis and Emergency Risk Communication (CERC) is different from day-to-day public health communication; summarizes the CERC framework and phase-based messaging; and outlines how risk perception impacts the way people process information about health threats. A student case study analyzes a Legionnaires’ disease outbreak using the CERC framework. Reflection questions are included at the end of the chapter.

Lifestyle Medicine is a practice grounded in evidence-based approaches, distinguishing it from unverified commercial wellness trends. It requires practitioners to critically interpret the evolving evidence base and communicate risks effectively to support shared decision making. While clinical trials for Lifestyle Medicine are less common than for pharmaceuticals, its interventions are nonetheless impactful and often preferred by patients. Epidemiology plays a crucial role in identifying associations between exposures and outcomes, although it cannot always establish causality. Understanding and communicating risk is vital, with absolute and relative risks offering different insights into the potential effects of interventions. The interpretation of evidence must consider both statistical and clinical significance, with confidence intervals providing a more nuanced understanding than p-values alone. Scepticism is necessary when interpreting clinical research to account for potential biases and confounding factors. Ultimately, consensus-driven approaches and trusted institutions guide practitioners in integrating Lifestyle Medicine into broader treatment guidelines.

Two years after the initial outbreak in 2020, SARS-CoV-2 continues to have a disruptive impact on day-to-day life for billions of people around the world. Despite high vaccination rates, high-income countries report record rates of infection with the Omicron variant in spring 2022. Adapting to the pandemic has led to significant behaviour change, such as increased working from home, social distancing, and mask-wearing. With this, perceptions of everyday situations (e.g., taking public transport or grocery shopping) have become risky in COVID-19 times. As risk tolerance is a key component to decision-making, changes in perceived risk may alter decision-making in the (post) COVID-19 world. In this chapter we summarise findings on risk-taking in times of COVID-19, with an aim to offer insights for policy purposes in this pandemic and for future pandemic preparedness. In particular, we summarise (i) the impact of COVID-19 on individual risk tolerance; (ii) the heterogeneity of risk tolerance during times of COVID-19; (iii) their relative effects on behaviour; and (iv) any evidence for risk compensation in the context of COVID-19.

In this chapter, we first review factors that may either produce vaccine hesitancy or lead people with favourable attitudes towards a vaccine to not get vaccinated soon enough. Then we propose behavioural science strategies for tackling these barriers to vaccine uptake and demonstrate that effective solutions vary based on individuals’ existing motivation to get vaccinated. This chapter ultimately seeks to synthesise behavioural science insights about promoting vaccinations and to highlight that aligning the intervention to the cause of individuals’ vaccination problem is key for effectively moving the needle for everyone.

In this chapter we distil the available systematic evidence of the unintended consequences of the COVID-19 pandemic on human behaviour, highlighting the contributions of behavioural science and the lessons learned from this multi-dimensional crisis. In light of this, behavioural science and policymaking could improve science communication and minimise the impact of false information, by leveraging various insights such as (i) nudging people to consider the accuracy of information and credibility of sources – for example, employing accuracy reminders; (ii) communicating risk more efficiently - for example,, using natural frequencies versus probabilities; and (iii) pre-exposing people to misinformation - for example,, adopting pre-emptive debunking. Behavioural science should thus continue informing the multi-disciplinary discussion about policy responses to future pandemics by systematically capturing and sharing the evidence about the direct and the spillover effects of future health crises on people’s health and behaviour.

We have reached the end of our stroll. We find ourselves in the company of Alexandre Dumas who, in 1850, wrote “The Black Tulip”. In it, he combines the stories of the tulip mania in the Netherlands with the tragic story of the brothers de Witt. In our final example of “About the data” we reconstruct the historic trading data of tulip bulbs, which turns out to be a detective story in its own right. Prices for tulip bulbs crashed on February 3, 1637. We also include the story of the growing of the first black tulip in 1986. Johan de Witt was tragically lynched by a politically motivated mob on August 20, 1672. With him, we meet a politician who, through his mathematical training, was able to solve an important problem from the realm of life insurance risk, the pricing of annuities. His publication “Waerdye” is our final example on risk communication. We leave the closing lines of our book to Shakespeare’s Hamlet, who spoke the following words to Horatio “There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.” We hope that we were able to convince you that these words very much apply to the realm of risk.

During the night of January 31 to February 1, 1953, the southwest coast of the Netherlands experienced a ferocious storm, killing over 1800 people, causing untold suffering and a major economic loss. As a consequence, the Dutch government initiated the Delta Project, which, through a combination of engineering works, should make the country safe for years to come. As part of this project, risk measures were introduced, like the so-called Dutch standard of a 1 in 10 000 years safety measure. Their statistical estimation was worked out and embedded in major engineering projects. These resulted in the construction of numerous new dikes along the coast. Through this example, we highlight several aspects of hazard protection. First, mathematics has an important role to play. Second, interdisciplinarity is key. Third, with such major and costly projects, spanning several generations, a clear communication to politicians as well as the public is both demanding as well as necessary.

We single out the 2006 L’Aquila earthquake in Italy as it yields a dramatic perspective on the problem of evidence-based communication. In the aftermath of this earthquake, several scientists were sentenced to jail for insufficiently clear communication related to an imminent earthquake. Though the sentences were later overturned, we can all learn from this example. It is interesting that this court case took place in the country that also tried Galileo Galilei in the seventeenth century for his defense of heliocentrism. A wonderful example in this context is provided by Galileo’s Dialogo published in 1632. In this publication, Galileo communicates his findings to a wider public through a series of dialogues between two philosophers and a layman. We present several parallels to present-day discussions on risk and science communication.

Expert testimony concerning risk and its communication to the trier of fact and other legal actors has important implications for some of the most significant legal decisions, from pretrial detention to capital sentencing. Although considerable psycholegal research has focused on the process of risk assessment and management, a limited number of studies have examined how risk is communicated and interpreted by judges, juries, and other legal decision-makers as well as the public. This chapter examines the primary methods of risk communication and critiques their usefulness based upon the legal contexts in which they are most commonly offered. In particular, legal decisions based upon risk concerning pretrial release, sentencing determinations, and sexually violent predator (SVP) laws are highlighted to discuss more general issues with risk communication in the legal system. Suggestions for more effective and accurate presentation of risk are offered, as well as the practical and legal policy implications of adopting such practices.