From ‘Airs, Waters, and Places’ to a warming world: Chronic illness, social inequities and the climate crisis

Abstract

The 2024 Teale Essay Prize invited resident or specialty and associate specialist doctors to consider how climate change affects healthcare, and the role of the physician. This theme aligns with the Royal College of Physicians’ commitment to sustainable healthcare. The link between climate and health is not new - Hippocrates described this relationship nearly 2,500 years ago.

More recently, catastrophic events, including crop failures due to extreme weather and the spread of diseases, have been attributed to climate change. These events can impact health directly, eg through trauma and infections, and indirectly, through rising rates of cardiovascular, respiratory, and mental health illnesses and other long-term conditions.

Here, I reflect on my winning essay, from the perspective of a trainee rheumatologist with an academic interest in social determinants of health. This article examines the global health challenges resulting from climate change, and considers how physicians can practice more sustainably.

‘For knowing the changes of the seasons, the risings and settings of the stars, how each of them takes place, he will be able to know beforehand what sort of a year is going to ensue … And if it shall be thought that these things belong rather to meteorology, it will be admitted, on second thoughts, that astronomy contributes not a little, but a very great deal, indeed, to medicine.’

‘On Airs, Waters, and Places – Part 2’, Hippocrates, 400 BCE

Hippocrates was the first documented physician to draw attention to the interplay between the climate and human health in his treatise ‘On Airs, Waters, and Places’.¹ Written in 400 BCE, it is thought to have been a guide for travelling physicians on the practice of medicine and points to consider when arriving in a new place. The above is taken from the second part of the publication; the deeper we dive into the work, the greater number of parallels we can draw to the modern-day practice of medicine, in an ever-changing and ever more complex world. It soon becomes clear that the climate and health have always been closely linked, but only now, with exponentially increasing effects of climate change, are we appreciating the need to act on the greatest threat to human health in the 21st century, as described by the World Health Organization.²

Climate change is contributing to humanitarian emergencies, ranging from wildfires, to heatwaves, to tropical storms and hurricanes, all of which are becoming more frequent and more intense.² It is not just the physical environment that is directly at risk – social and economic aspects, as well as the functioning of health systems, are being affected by climate change, effectively making the threat multifaceted and potentially reversing decades of progress made in the development of health and care systems. The weather and climate hazards affect health directly and indirectly, not just increasing the risk of diseases such as infections, malnutrition and heat stress, but also non-communicable diseases.

The numbers are stark. Climate change is expected to lead to approximately 250,000 additional deaths per year between 2030 and 2050, mainly due to undernutrition, malaria, diarrhoea and heat stress. The direct costs to healthcare, excluding expenditure on agriculture, water and sanitation, is estimated as $2–4 billion per year by 2030.² Areas with weak healthcare infrastructure will therefore be least likely to cope without adequate preparation and aid in responding to this crisis, mainly in developing countries. Progress made over the last several decades, in areas such as global health and poverty reduction, is likely to be undermined by the threat of climate change, exacerbating health inequalities and access to healthcare. Approximately 12% of the global population spend at least 10% of their household budget on health service use. In areas where healthcare is dependent on insurance, the poorest people are largely uninsured, so the health stresses that already annually lead around 100 million people into poverty will simply be compounded.

To the physician practising medicine in the UK, it can all seem very distant. However, climate change is already having multiple impacts at the individual and population level. There were over 3,200 excess deaths reported in England during the summer heatwave of 2022, while 28,000–36,000 deaths are attributed to air pollution annually.³ The UK Health Security Agency (UKHSA) predicts that heat-related deaths could increase by 580% by the 2050s.^3,4 Extreme weather outside the UK can disrupt food chains, leading to lack of availability and volatile pricing. In this sense, climate change and social determinants of health are closely intertwined, with factors such as access to nutrition, geo-politics and cost of living having very real impacts on human health.⁵

Direct effects on health, especially non-communicable diseases, are also increasing. Many medical specialties have reported deleterious effects on human health from climate change, including allergy, cardiovascular, respiratory and psychiatry. Respiratory health in particular bears the brunt of climate change and can be a key indicator of our planetary health.⁶ Extreme heat and cold, disturbances to seasonal virus fluctuations, smoke resulting from wildfires, emergence of new zoonotic respiratory viruses as well as air pollution are all key contributors to an increase in respiratory diseases. An often-overlooked weather disturbance in respiratory health is flooding, which can directly and indirectly lead to chronic respiratory decline, for example due to contaminants such as toxins and water-borne pathogens and mould growth in damp environments. Children, older adults and the immunocompromised are most at risk, with research indicating that damp environments increase the risk of conditions such as asthma, bronchitis, chest infections and allergies, to name a few.⁶

Lesser-known effects are those that impact rarer conditions, and perhaps those that we may not immediately associate with climate change. An important example of this are the rheumatic musculoskeletal diseases. As a trainee in both rheumatology and general internal medicine, it is clear to me that climate change is likely to have an increasing impact on the presentation, diagnosis and management of the rheumatological conditions we see in inpatients and outpatients, which have been relatively neglected when it comes to research on the intersection of climate change and health.⁷ Nonetheless, evidence is emerging particularly on the association between air pollution and increased risk of the development of rheumatoid arthritis and gout flares, for example, recently summarised in a white paper published by the American College of Rheumatology.⁷ Increased heat vulnerability has been shown to be associated with greater odds of recurrent hospitalisations across rheumatic conditions – this can be for a variety of reasons, including the increased risk of infections and dehydration. Suggested mechanisms include epigenetic changes, oxidative stress and increased inflammatory cytokines.⁷ Such is the drive to increase the awareness of climate change in the rheumatology community, a session on planetary health was convened at the European Congress of Rheumatology in 2024, received as one of the most-attended sessions and highlights of the entire meeting.

Climate change is also increasingly recognised as a social determinant of health.⁸ Climate change disproportionately affects children, older adults and those who work primarily outdoors, for example through heat stress, physical injury during weather disturbances and flooding, as well as increased risk of infections. Add in factors such as poverty and structural racism, and there ensues a perfect storm associated with these downstream effects of climate change, leading to increased rates and severity of conditions such as cardiovascular and respiratory disease. Socioeconomically vulnerable groups are already most affected by rising food prices, and most likely to live in less structurally sound and overcrowded housing.

The fatal consequences of living in areas of high air pollution sadly were highlighted by the death of a 9-year-old girl in London in 2013, following an episode of severe asthma. She became the first person in the UK to have air pollution listed as a cause of death on her certificate.⁹ Vulnerable groups face other challenges when adapting to a changing climate, such as lack of access to air-cooling units in heatwaves due to financial constraints, and difficulty recovering financially from floods and storms. The climate crisis is therefore just another cog in the societal drivers of health.

Evidently, the health effects of climate change will affect us all, whether it be as patients or physicians. It is clear that immediate and effective action is required to prevent these health risks, which are compounded by factors such as an ageing population (increasing vulnerability to extreme heat) and existing social inequalities and deprivation.^4,10 Over the last couple of years, the Royal College of Physicians (RCP) has been actively campaigning for climate and sustainability policies which aim to protect public health, and is signed up to the UK Health Alliance on Climate Change (UKHACC) Commitments, a set of guiding principles designed by UKHACC to help health organisations take steps to mitigate and adapt to climate change.¹¹ In July 2024, the RCP published the Green physician toolkit, which brings together the evidence on health and climate change and suggests actions that physicians can take in their day-to-day practice. Building on ideas within the ‘RCP view on healthcare sustainability and climate change’ report published a year earlier, the toolkit contains practical advice such as reducing unnecessary prescribing by using shared decision-making approaches, reducing blood testing where clinically appropriate, limiting the environmental impact of travel and encouraging sustainable quality improvement projects within organisations.^3,12

It is of course challenging for physicians to prioritise sustainable practices at a time when there are more pressures than ever before on the NHS. However, the advice laid out in the toolkit is designed to promote small practical changes, which over time will deliver wider benefits for all. Advocacy is also at the heart of the recommendations, with a call to incorporate sustainable healthcare in governance meetings, and campaign for greener travel options for both staff and patients, for example remote consultations where safe and appropriate, and remote working during non-clinical shifts. Physicians are also uniquely placed as trusted members of the community, and can therefore help members of the public, in a sensitive manner, understand how the climate affects their health and how to mitigate against this. Examples include discussion around smoke and pollution exposure in relation to respiratory diseases, heat and sun protection during heatwaves, and places to access warm and cool spaces during extremes of temperature (especially for vulnerable groups).

At an organisational level, there is a call to disinvest from fossil fuel companies and to instead focus on implementation of plans that carry sustainability at the heart. Equally important is the need to be alert to and aware of groups who are most vulnerable to the health effects of climate change such as children, older adults, the immunocompromised, those with long-term health conditions and the socially deprived. Mental health impacts of events such as flooding and heat stress should also be considered, especially in light of their increasing frequency.

It is encouraging that national and international healthcare organisations, as well as specialty organisations and congresses, are now making climate change a priority for high-level discussion and policy-making. The healthcare sector is making progress towards efforts to tackle climate change, but there is a need for increased ambition, in which every person and organisation can play a part in driving change. To update Hippocrates’ words for the modern-day physician, the climate ‘contributes not a little, but a very great deal, indeed, to medicine’.#

CRediT authorship contribution statement

MD is the sole author of this work. She is responsible for its conceptualisation, initial and final draft, reviewing and takes full responsibility for its contents.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.