Planetary health and clinical practice: From concept to consultation

By 2026, we have moved past the climate crisis being a distant threat; it has become our daily clinical reality. As physicians, we now witness its effects daily: The elderly patient with heatstroke during an unprecedented summer heat wave, the child with an asthma exacerbation triggered by wildfire smoke, and the otherwise healthy individual presenting with unexplained thrombocytopenia, later linked to microplastic bioaccumulation. The World Health Organization has declared climate change the greatest health threat of the 21st century.[1] However, how many of us routinely integrate planetary health considerations into our clinical consultations? The epidemiological transition wrought by environmental degradation demands our urgent attention. Between 2020 and 2024, heat waves alone caused 10,781 excess deaths in England.[2] Across Europe, more than 60,000 people died due to heat in the summer of 2022, with another 47,000 succumbing to high temperatures in 2023.[3] These are not merely statistics, but they are our patients. Air pollution, primarily from fossil fuel combustion, contributes to over 10 million annual deaths globally, affecting nearly every organ system.[1] Fine particulate matter 2.5 is now implicated in cardiovascular disease, stroke, lung cancer, diabetes, cognitive decline, and adverse perinatal outcomes.[4] The clinical presentations are protean, yet the underlying environmental determinants often remain unaddressed in our consultations. Perhaps, most alarming is the emerging evidence regarding microplastics. A 2024 New England Journal of Medicine study detected microplastics in the atherosclerotic plaques of 58% of patients undergoing carotid endarterectomy, with affected individuals facing a 4.5-fold increased risk of adverse cardiovascular events.[5] Recent autopsy studies have revealed microplastic bioaccumulation in human brains, approximately 5000 μg/g in nondemented individuals, with 2–10 times higher levels in those with dementia.[1] Physicians are uniquely positioned to address these threats. A recent Royal College of Physicians survey found that 75% of 490 responding physicians were worried about climate change’s effects on patient health, yet only 61% considered environmental impacts in their clinical decisions, citing lack of time, training, or organizational support.[2] This gap between concern and action represents both a challenge and an opportunity. Table 1 summarizes key environmental health threats and corresponding clinical actions that can be integrated into routine practice.Table 1: Planetary health threats and clinical actions across medical specialitiesPractical Steps for the Clinician How then shall we practice? The emerging literature offers concrete guidance. In respiratory medicine, switching from metered-dose inhalers to dry powder inhalers where clinically appropriate can reduce carbon footprint by 50–100 fold.[3] The Danish Health Authority has recommended this practice since 2022. In prescribing, we must confront polypharmacy. Between 30% and 50% of medications for long-term conditions are not taken as intended and 10% of all primary care prescriptions in England are estimated to be overprescribed.[7] Deprescribing, when done safely with patient agreement, reduces both harm and environmental impact.[3] For diabetes care, choosing reusable insulin pens over disposable alternatives and considering oral medications where appropriate aligns clinical and environmental goals.[8] The Royal College of Physicians’ updated Green Physician Toolkit provides specialty-specific guidance.[2] Individual clinical actions, while necessary, are insufficient. We must advocate for systemic change. The National Health System’s commitment to net zero by 2040 for directly controlled emissions, and by 2045 for influenced emissions, demonstrates what is possible with political will.[2] Similar commitments are needed globally. Research priorities must include comparative effectiveness studies of care pathways, standardized metrics for environmental impact, and implementation science to overcome barriers to sustainable practice.[9] The BIOQUALIM project’s transdisciplinary approach to studying the planetary health diet’s role in preventing noncommunicable diseases offers a model.[10] Conclusion Planetary health is clinical medicine. The boundaries between environmental health, public health, and individual patient care have dissolved. As physicians, we must recognize environmental determinants of disease, integrate climate counseling into our consultations, and advocate for sustainable health systems. The question is no longer whether planetary health belongs in clinical practice, but how quickly we can make it routine. The Lancet’s 2026 editorial, “No health without peace,” reminded us that foundational determinants underpin all clinical progress. To that we add: “no health without a stable planet.” For our patients today and generations to come, the time to act is now.