Introduction

In this scoping review of reviews, we aim to map the evidence for extreme heat related adaptation strategies by health systems with particular focus on how heat-vulnerable populations are considered.

Global warming and climate change is positively correlated with human activity, not limited to burning fossil fuels and unsustainable energy use, leading experts to predict global surface temperatures will increase by 1.5°C in the first half of the 2030s [2]. Climate change is driving an increase in the frequency, intensity, and duration of extreme weather events, such as wildfires, floods, and heatwaves [3]. These events are known to have an impact on health systems, including driving hospital admissions and length of stay, over heating facilities, and worsening symptoms for people with existing health conditions [4]. The COVID-19 pandemic has shown us that many health systems were ill prepared to cope with the additional pressures that result from such a prolonged emergency. As a result, it has become increasingly common for health systems to intervene by enhancing disaster preparedness and planning for extreme weather emergencies [3]. This review protocol focuses specifically upon health system adaptation strategies for extreme heat events.

Extreme Heat events are defined as a period of sequential warm days, often referred to as a heat wave, where the maximum and minimum temperatures are unusually high and exceed a threshold set by local governments which vary by region, for example in the United Kingdom these thresholds range between 25°C and 28°C [5–7]. These events impact infectious disease transmissions and undermine people’s mental health and livelihoods [8]. This increase in temperature combined with land use changes are making more regions suitable for the transmission of vector-borne diseases, for example increasing rates of dengue in Central and South America [8]. Exacerbation of existing mental health symptoms during extreme heat can lead to increased risk of suicide among vulnerable individuals. Livelihoods are affected as certain commercial activities can put workers at risk, especially those who work outside during extreme heat [9].

Globally, deaths during a heatwave are most likely to occur among vulnerable populations, we define this as: the very young (<5), and older people (>65) who live in their own homes, care homes, or are admitted to the hospital [10]. Heat-vulnerable communities include those with existing mental health concerns, metabolic syndrome, and from ethnic minority communities [11, 12]. Increased demand upon health services is a problem in extreme heat, particularly among underserved groups. Vulnerability to heat events is compounded by inequity, intersectionality and marginalisation with variation by geographic region. Several types of adaptation strategies have been implemented by health systems to mitigate these health risks.

Adaptation strategies are defined by the Interplanetary Commission on Climate Change (IPCC) as “the process of adjustment to actual or expected climate and its effects in order to moderate harm or take advantage of beneficial opportunities” [8]. It has been suggested that adaptations could reduce pressures on healthcare services and deliver £10 in economic benefits for every £1 invested [13]. However, recent reviews [14] flag that current adaptations are insufficient, do not adequately consider health equity, and require better coordination between organisations. The consequences of this current adaptation approach are that many interventions, such as early-warning systems and behavioural risk messaging, do not reach their intended targets (e.g. vulnerable groups), due to barriers including cultural differences, language, and a lack of trust, particularly among ethnic minority populations.

Re-defining who is considered heat-vulnerable is important for targeted adaptations to be effective. Interconnected factors influence vulnerability to extreme heat including age, pre-existing medical conditions, disability, socioeconomics, and the built environment. Addressing heat exposure by individuals in workplaces (e.g. working outside) is another challenge. This scoping review aims to expand understanding of who is considered heat-vulnerable; why; and how to reach them effectively, by examining targeted policies and actions to mitigate the adverse effects of extreme temperatures on at-risk populations.

Moreover, we aim to consider how local situational awareness is incorporated with adaptation so that risk communication plans are grounded in local knowledge and experience. We define local situational awareness as the development of a shared understanding of health needs in local communities, cross-jurisdictional information sharing and enhanced coordination, to ensure the implementation of adaptation strategies are targeted and effective [15]. For example, research finds that messages about the dangers of hot weather are not getting through to certain heat-vulnerable communities [11] We will highlight examples of how tailored messaging (e.g. using diverse channels; languages; and formats; or incorporating individuals from heat-vulnerable communities) could build trust with message receivers and increase the reach of heat risk education, reducing inequities in health outcomes.

Eligibility criteria

Methods

The proposed scoping review will be conducted in accordance with the PRISMA-ScR standards for reporting scoping reviews [20].

Ethics and dissemination

This study does not require ethical approval as it is a scoping review protocol. The findings will be published in scientific journals and disseminated electronically. All relevant literature search results such as government documents, journal articles, and publications, will be made available in a public repository.

Strengths and limitations of this study

The breadth of this research question (the range of potential adaptation interventions at different levels of the health system; plus the global coverage) necessitated the focus on review-level literature, to the exclusion of primary studies. We recognise this as a limitation; however, our survey of current grey literature from our network partners is designed to mitigate the associated risks by bringing the review up to date. We believe the unique contribution of our review will be to provide a helicopter view of the international literature to identify where there are gaps for further research or more focused systematic reviews.

Supporting information