Environmental Impacts on Public Health and Well-being

The environment we live in shapes our health far more than most people realize. From the air we breathe to the economic conditions we navigate, environmental factors are deeply intertwined with public health outcomes. Rising temperatures, worsening air quality, economic downturns, and mass migration are not isolated crises – they converge to create compounding health risks for communities worldwide. Understanding these connections is essential for building healthier, more resilient societies.

Economic and social factors in public health 🔗

Public health does not exist in a vacuum. It is closely tied to social determinants of health – conditions like income, employment, housing, and education that shape how healthy a population can be. When economies falter, health outcomes tend to worsen, and the most vulnerable groups bear the heaviest burden.

How economic crises affect health 🔗

Economic downturns reduce access to healthcare, nutritious food, and safe housing. During periods of recession or financial instability, governments often cut public health budgets at the very moment demand for services increases. Job losses lead to loss of employer-provided health insurance in many countries, pushing people into unmet medical need.

The COVID-19 pandemic was a stark example. Beyond the direct toll of infection, economic disruption caused by lockdowns led to depression, stress, isolation, and other mental health challenges, especially among migrant and low-income workers who had little financial cushion. In many countries, the economic fallout worsened existing inequalities – those already at the margins of the health system were pushed even further from care.

Poverty itself is a health risk. People living in lower socioeconomic conditions are more likely to be exposed to environmental hazards such as polluted air, unsafe water, and substandard housing. They are also less likely to have the resources to adapt to environmental threats like extreme heat or flooding.

Migration and its public health implications 🔗

Migration is one of the defining features of our era, and it carries significant public health implications for both migrants and host communities. Refugees and migrants often come from communities affected by war, conflict, natural disasters, or economic crisis, and the migration journey itself can expose them to communicable diseases, malnutrition, injuries, and severe psychological distress.

Once migrants arrive at their destination, barriers do not disappear. Language differences, institutional discrimination, restricted access to health services, and social exclusion create ongoing health risks. These factors can contribute to higher rates of noncommunicable diseases and poorer mental health outcomes among migrant populations. During economic downturns, migrant workers are often the most vulnerable to job losses and worsening working conditions, which directly impacts their quality of life and health.

There is also a phenomenon known as the “healthy migrant effect” – migrants may arrive in better health than the host population. However, this advantage tends to erode over time as migrants face the social and economic stresses of their new environment. This pattern highlights the powerful role that social determinants play in shaping long-term health trajectories.

Migration also affects the healthcare systems of origin countries. When trained health professionals emigrate in large numbers, a “brain drain” depletes the local health workforce, weakening healthcare delivery in communities that need it most.

Environmental health risks 🔗

Environmental change – driven primarily by human activity – has become the single largest category of emerging health threats globally. The World Health Organization reports that all aspects of health are affected by climate change, from clean air and water to food systems and livelihoods. The effects are both direct (injuries from extreme weather events) and indirect (disrupted food supply, spread of infectious diseases, mental health deterioration).

Heatwaves: a growing killer 🔗

Extreme heat is rapidly becoming one of the deadliest consequences of climate change. Between 2000 and 2019, approximately 489,000 heat-related deaths occurred each year globally, with 45% of those in Asia and 36% in Europe. Heat-related mortality among people over 65 has increased by roughly 85% between the early 2000s and the early 2020s.

Heatwaves do not affect everyone equally. Older adults, outdoor workers, people with pre-existing cardiovascular or respiratory conditions, and residents of urban areas (where the urban heat island effect intensifies temperatures) face the greatest risks. The 2003 European heatwave, which killed approximately 70,000 people, demonstrated the devastating toll that insufficient public health preparedness can take.

Beyond immediate mortality, sustained heat reduces labour productivity, disrupts schooling, compromises essential health services during power outages, and contributes to deteriorating mental health.

Air pollution: a persistent threat 🔗

Air pollution remains the single largest environmental health risk factor worldwide. Exposure to fine particulate matter (PM2.5) and ground-level ozone is linked to respiratory disease, cardiovascular disease, stroke, lung cancer, and premature death. In 2021, air pollution was the second leading risk factor for death among children under 5, after malnutrition, contributing to roughly 700,000 deaths in that age group alone.

While PM2.5 levels have stabilized or decreased in some high-income countries, ozone pollution is a growing concern. Ninety-three percent of the global population lives in areas where peak seasonal ozone exceeds WHO guidelines. Countries in the Middle East, South Asia, and East Asia experience the highest average ozone exposure.

When heat and air pollution combine 🔗

One of the most alarming environmental health findings in recent years is the synergistic effect of heatwaves and air pollution. These two hazards frequently co-occur – hot, stagnant air traps pollutants at ground level – and their combined impact on health is greater than the sum of their individual effects.

Research from California found that mortality risk on days with combined extreme heat and high PM2.5 increased by an estimated 21%, and for adults over 75, the risk rose by more than a third. Heat can also trigger chemical reactions that increase ground-level ozone, creating a dangerous feedback loop especially in cities.

This dual threat has major implications for urban planning, healthcare preparedness, and climate adaptation strategies. Cities need integrated warning systems that account for both temperature and air quality, rather than treating them as separate risks.

Other climate-driven health risks 🔗

Beyond heat and air quality, environmental change contributes to a wide range of health threats. Prolonged droughts have caused famine, mass migration, and humanitarian crises, and are far worse than floods from a disease perspective because of reduced access to fresh drinking water and the creation of stagnant water pools that breed disease.

Wildfires – which have increased in frequency across 114 of 196 countries – release enormous quantities of particulate matter and toxic gases, affecting air quality across vast distances. In 2023, Canadian wildfires degraded air quality in the northeastern United States, with New York City experiencing its worst daily PM2.5 concentration in over 50 years. Climate change also shifts the geographic range of disease-carrying vectors such as mosquitoes, expanding the reach of illnesses like dengue, malaria, and Zika into previously unaffected regions.

Floods, storms, and rising sea levels contaminate drinking water, destroy sanitation infrastructure, and displace entire communities, creating conditions ripe for disease outbreaks and long-term mental health consequences.

Public health policy and prevention 🔗

Given the scale and complexity of environmental health threats, strong public policy is not optional – it is the primary tool for protecting populations. Effective policy works at multiple levels: preventing environmental hazards, preparing health systems to respond, and ensuring equitable protection for the most vulnerable.

The role of prevention-focused policy 🔗

Prevention is far more cost-effective than treatment when it comes to environmentally driven health problems. The WHO’s 2024 Compendium of interventions on environmental health features over 500 evidence-based strategies covering air pollution, water and sanitation, chemical exposure, climate adaptation, and occupational health. These interventions are designed to be integrated into broader public health and sustainable development frameworks.

At the national level, policy, systems, and environmental (PSE) approaches have become central to modern public health. These operate at the macro level – changing laws, organizational procedures, or physical environments – to affect large populations. For example, clean air regulations, urban greening policies, building codes that address heat resilience, and investment in public transportation all reduce environmental health risks at scale.

Heat action plans and early warning systems 🔗

The 2003 European heatwave was a turning point for heat-health policy. The devastating death toll revealed massive gaps in public health preparedness, and many countries responded with sweeping reforms. These included better heatwave prediction and preparedness systems, improved building design, air conditioning for hospitals and retirement homes, training for health professionals, and planned check-ins on vulnerable individuals during heat events.

Today, heat action plans are recognized as essential components of climate adaptation. The WHO works with national health sectors to develop heat early warning systems, emergency response protocols, and cooling strategies for high-risk settings. However, adoption remains uneven. Many low- and middle-income countries, which face some of the highest heat exposures, still lack comprehensive heat-health plans.

Addressing health equity in environmental policy 🔗

Environmental health risks are not distributed equally. Low-income communities, racial and ethnic minorities, older adults, children, and migrant populations consistently face higher exposure to pollution, extreme heat, and climate-related disasters, while having fewer resources to cope. This is why health equity must be a central pillar of environmental health policy.

Effective policy responses include targeting investments toward disadvantaged communities, ensuring access to healthcare for migrant populations, strengthening primary healthcare infrastructure in climate-vulnerable regions, and integrating health considerations into climate, energy, and urban planning decisions. The WHO’s “Health in All Policies” approach recognizes the need for intersectoral collaboration – environmental health cannot be addressed by health ministries alone but requires coordination across government and civil society.

Building climate-resilient health systems 🔗

Health systems themselves are vulnerable to environmental change. Power outages during heatwaves, flooding of healthcare facilities, supply chain disruptions, and increased patient loads during climate events can overwhelm even well-resourced systems. A 2025 systematic review found that health systems must develop operational resilience to handle the growing challenges posed by environmental change, including the capacity to adapt quickly to critical conditions while also reducing their own carbon emissions.

Building resilience means investing in sustainable healthcare infrastructure, training the health workforce in climate-related health risks, integrating climate data into public health surveillance, and ensuring that essential services can continue operating during extreme events. It also means decarbonizing health systems – which are significant contributors to greenhouse gas emissions – to avoid further worsening the problem they are trying to address.

The path forward 🔗

The relationship between the environment and public health is not a future concern – it is a present reality. Economic crises push vulnerable populations away from healthcare. Migration exposes millions to compounding health risks. Climate change is intensifying heatwaves, worsening air pollution, and spreading infectious diseases into new territories. These challenges are interconnected, and so must be the responses.

The evidence is clear: protecting the environment is protecting public health, and protecting public health requires policies that address the root causes of environmental degradation. Every investment in cleaner air, safer water, climate-resilient infrastructure, and equitable healthcare access is an investment in human well-being.

What do you think? How prepared is your community for the combined health effects of climate change, economic disruption, and environmental degradation? Should environmental health considerations be integrated into all areas of government policy – not just health departments?

References

1. https://pmc.ncbi.nlm.nih.gov/articles/PMC10665605/
2. https://www.who.int/news-room/fact-sheets/detail/refugee-and-migrant-health
3. https://www.iom.int/speeches-and-talks/social-determinants-health-context-migration-and-time-economic-crisis
4. https://www.healthknowledge.org.uk/public-health-textbook/medical-sociology-policy-economics/4c-equality-equity-policy/migration
5. https://www.who.int/news-room/fact-sheets/detail/climate-change-and-health
6. https://www.who.int/news-room/fact-sheets/detail/climate-change-heat-and-health
7. https://www.cleanairfund.org/news-item/hei-global-air-pollution-report/
8. https://www.wri.org/insights/extreme-heat-air-pollution
9. https://pmc.ncbi.nlm.nih.gov/articles/PMC11998295/
10. https://www.who.int/news/item/29-07-2024-who-announces-the-2024-updated-compendium-of-interventions-on-environmental-health
11. https://pmc.ncbi.nlm.nih.gov/articles/PMC11627177/
12. https://www.mdpi.com/1660-4601/22/2/232