as direct threats to heart health
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Consider a retiree in western Sydney living with heart failure, a condition in which the heart pumps too weakly.
Overnight the bedroom holds 31 degrees and smoke tints the dawn brown.
Thermometers and air monitors each record one hazard, while the heart absorbs both at once.
A 2026 European Society of Cardiology (ESC) statement names air pollution and heat as key contributors to heart disease.
Shared pathways include inflammation, oxidative stress (cell damage from reactive molecules) and endothelial dysfunction (impaired blood vessel lining).
Clinical guidelines and public health strategies still underrepresent them.[7]
Extreme heat triggers dehydration, which speeds the heartbeat and activates the sympathetic nervous system. That branch of the nervous system accelerates the heart and narrows blood vessels.
Reviewers also cite haemoconcentration, a rise in blood-cell concentration, and hypercoagulability, an excess tendency to clot.[1]
Epidemiological studies link heat to ischaemic heart disease, stroke, heart failure and arrhythmia. Ischaemic heart disease means reduced blood flow to the heart muscle, while an arrhythmia is an irregular heartbeat. The review adds that researchers still need to establish the underlying mechanisms.[1]
Heat stroke, a life-threatening failure of body temperature control, diverts blood flow away from the gut. Starved of blood, the gut lining becomes more permeable. Bacterial toxins such as lipopolysaccharide then enter the bloodstream.[1]
Across 266 studies, a 2022 meta-analysis, which statistically pools study results, quantified the penalty. Each 1°C rise in temperature lifted cardiovascular mortality risk by 2.1 per cent. Stroke and coronary heart disease carried the highest risks.[8]
PM2.5 describes airborne particles measuring 2.5 micrometres or smaller, fine enough to lodge deep in the lungs. The ESC statement traces the harm of pollution and heat to oxidative stress, inflammation, endothelial dysfunction and circadian disruption. Circadian disruption means interference with the body's 24-hour internal clock.[7]
Hospital records from 20 US states underpin a 2026 Nature Communications analysis. Each 1 microgram per cubic metre of wildfire-specific PM2.5 carried significantly higher hospitalisation risk for every cardiopulmonary disease. Heart failure carried a 10 per cent higher risk and asthma 16 per cent.[2]
Wildfire-specific PM2.5 contains more submicron particles (under one micrometre), carbon-based material and polar organic compounds than other PM2.5. Non-wildfire PM2.5 still dominates the air, averaging 20 to 27 times higher concentrations. Per unit, however, smoke carries the greater cardiopulmonary hospitalisation risk.[2]
JACC (Journal of the American College of Cardiology) published a multicountry study in July 2026 covering nearly 6 million cardiovascular deaths across 755 locations. Days combining heatwaves and substantial fire smoke carried a 12 per cent increase in cardiovascular mortality. Heatwaves alone raised the risk 8.3 per cent and smoke alone 1.4 per cent.[3]
Outdoor air pollution cut global life expectancy by 2.9 years in 2015, a 2020 Cardiovascular Research study estimated. That loss exceeds the toll from tobacco smoking. The authors identified cardiovascular disease as a leading pathway of harm.[9]
University of Adelaide researchers measured Australia's heat toll across 2003 to 2018. High temperatures cost 49,483 healthy years of life to cardiovascular disease each year. That share equals 7.3 per cent of the national cardiovascular disease burden.[4]
Projections show the burden more than doubling by the 2050s under a high-emissions scenario. Lead researcher Professor Peng Bi said the study combines climate change, population shifts and adaptation strategies. Bi expects the link between heat and heart disease to hold in many parts of the world.[4]
Smoke from the 2019-20 Black Summer fires caused an estimated 429 premature deaths. It also drove 3,230 hospital admissions for cardiovascular and respiratory disorders. Researchers from the University of Tasmania put the smoke-related health costs at $1.95 billion.[10]
Georgia Chaseling of the University of Sydney co-wrote a statement the European Heart Journal published on 8 October 2026. Older adults with heart disease face up to seven times the risk of dying in a heatwave. Authors say tailored heat plans can prevent these deaths.[5]
For heart failure, clinicians should monitor hydration, weight, electrolytes (blood salts) and medication use carefully. For arrhythmias, attention should turn to salt and mineral balance, hydration, palpitations, dizziness and fatigue. For people with hypertension, or high blood pressure, home monitoring helps prevent heat-related low blood pressure and falls.[5]
Patients should keep taking cardiovascular medication and consult a clinician before any change, the authors stress. Most research on heat and common medications comes from young, healthy individuals rather than typical older patients. That gap limits the evidence behind medication advice during heatwaves.[5]
Heat also strains emergency departments, primary care, home care and social services. The authors call for heat action plans, surge capacity and proactive outreach to socially isolated people. Coordination between health providers, emergency services, public health agencies and local authorities underpins the response.[5]
The same 2020 analysis calculated the gain from cleaner air. Removing fossil fuel emissions would lift global life expectancy by 1.1 years. Removing every controllable human-made emission would lift it by 1.7 years.[9]
Australia's first National Health and Climate Strategy committed to a National Heat-Health Action Plan in 2023. In February 2026 the Climate and Health Alliance urged Minister Mark Butler to expedite its release. That call came more than two years after the commitment.[6]
The ESC statement calls for heart-healthy urban design, stricter emissions legislation and equitable access to clean environments. Earlier ESC advice on air pollution now extends to climate change, noise, light and chemical pollution. It casts cardiologists as advocates well placed to bridge science, clinical care and policy.[7]
Menzies Institute researchers argue that bushfire preparedness must include smoke measures. They name warning apps, clean air shelters and air filters in homes and workplaces. The Menzies team developed AirRater, an air-monitoring app that people used across Australia during the bushfires.[10]
Evidence from cardiology, public health and atmospheric science now points the same way. Heat, smoke and fine particles strain the heart through shared pathways, and their combination raises the toll. The authors of the October ESC report describe heatwave deaths as preventable.
Australia holds the data, the clinicians and the memory of Black Summer. Governance has lagged, with health groups still urging release of a promised heat-health plan in February 2026. Costs from Black Summer smoke alone reached $1.95 billion.
Accountability rests with governments that write the plans, health services that deliver them and emitters that fuel the hazards.
Preparation before the next heatwave or smoke event offers the clearest protection.
1. Heat and the Heart (Yale Journal of Biology and Medicine, 2023). Peer-reviewed review of how dehydration, hypercoagulability and sympathetic activation link extreme heat to heart disease.
2. Cardiopulmonary hospitalization risks from wildfire-specific and non-wildfire PM2.5 in 20 US states (Nature Communications, 2026). Hospital-record analysis showing higher cardiopulmonary risk per unit of wildfire-specific PM2.5.
3. Fire-Sourced Air Pollution, Heat Waves Together Linked to Higher CV Mortality Risk (American College of Cardiology summary of a JACC study, 2026). Summary of a multicountry study of combined heat and smoke exposure across nearly 6 million cardiovascular deaths.
4. Burden of cardiovascular disease caused by extreme heat in Australia to more than double by 2050 (European Society of Cardiology press release). University of Adelaide-led European Heart Journal study quantifying Australia's heat-related cardiovascular burden and its projected growth.
5. Report shows how we must protect people living with heart disease in heatwaves (European Society of Cardiology, 8 October 2026). Summary of a new European Heart Journal statement on protecting cardiovascular patients before, during and after heatwaves.
6. We need a national plan for extreme heat (Climate and Health Alliance, 4 February 2026). Media release urging the federal Health Minister to release the National Heat-Health Action Plan committed in 2023.
7. Environmental risk factors and cardiovascular health: A clinical consensus statement of the European Society of Cardiology (European Heart Journal, 2026). Consensus statement on air pollution, heat and other environmental drivers of heart disease and the mitigation strategies required.
8. Heat exposure and cardiovascular health outcomes: a systematic review and meta-analysis (The Lancet Planetary Health, 2022). Pooled analysis of 266 studies quantifying cardiovascular mortality risk per 1°C rise in temperature.
9. Loss of life expectancy from air pollution compared to other risk factors: a worldwide perspective (Cardiovascular Research, 2020). Global modelling study comparing life expectancy lost to air pollution with tobacco smoking and other risks.
10. Smoke-related health costs of 2019-20 bushfires estimated at $1.95 billion (UNSW Bushfire Hub and University of Tasmania). Menzies Institute estimate of Black Summer smoke deaths, hospital admissions and health costs, with recommended smoke protections.
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