How Environmental Factors Influence Human Health: Key Risks and Solutions

The environment we live in shapes our health in ways we often underestimate. From the air we breathe to the water we drink, environmental factors play a direct role in causing or preventing disease. Globally, environmental risks account for millions of premature deaths every year – and the burden falls hardest on the most vulnerable populations. Understanding these risks is the first step toward protecting ourselves and building healthier communities.

Air pollution and its health risks 🔗

Air pollution is one of the most widespread environmental threats to human health today. It originates from a range of sources – industrial emissions, vehicle exhaust, power generation, agricultural burning, and even household cooking with solid fuels. According to the WHO, the combined effects of outdoor and indoor air pollution cause approximately 7 million premature deaths globally every year.

How air pollution affects the body 🔗

The primary route of exposure is through the respiratory system. When we inhale pollutants like fine particulate matter (PM2.5), nitrogen dioxide, sulfur dioxide, and ground-level ozone, they trigger inflammation, oxidative stress, and immune suppression in our cells. PM2.5 particles are especially dangerous because they are small enough to penetrate deep into the lungs and enter the bloodstream, affecting virtually every organ in the body.

The diseases most strongly associated with air pollution exposure include stroke, ischaemic heart disease, chronic obstructive pulmonary disease (COPD), lung cancer, and pneumonia. There is also growing evidence linking polluted air to diabetes, adverse pregnancy outcomes such as low birth weight, cognitive impairment, and neurodegenerative diseases like dementia. Children, the elderly, pregnant women, and people with pre-existing conditions face the highest risks.

Air pollution is now recognized as the second leading risk factor for noncommunicable diseases after tobacco smoking. Roughly 90% of deaths from ambient air pollution occur in low- and middle-income countries, where air quality is poorest and regulatory infrastructure is weakest.

Clean air initiatives 🔗

Efforts to reduce air pollution are gaining momentum at international and national levels. In 2025, WHO Member States adopted an updated road map committing to halve the health impact of air pollution by 2040, compared to 2015 levels. This target calls for a multisectoral approach – reducing emissions from transport, energy production, industry, and waste management while also strengthening healthcare systems to respond to pollution-related diseases.

At the city level, practical interventions include expanding cycling infrastructure, transitioning to renewable energy, improving public transportation, and enforcing stricter vehicle emission standards. The European Union’s revised Ambient Air Quality Directive, which entered into force in December 2024, sets stricter air quality standards aligned more closely with WHO guidelines – a model that other regions can learn from.

Climate change impacts on health 🔗

Climate change is no longer a distant threat – it is actively reshaping global health outcomes. Rising temperatures, shifting weather patterns, and increasingly frequent extreme weather events are creating new health risks and amplifying existing ones.

Direct health effects 🔗

Extreme heat is one of the most immediate dangers. Heatwaves cause heat exhaustion, heatstroke, and cardiovascular failure, and they disproportionately affect older adults, outdoor workers, and people in urban areas without adequate cooling. The 2025 Lancet Countdown report found that 12 of 20 key indicators tracking climate-related health threats reached record levels, with heat exposure alone causing the loss of 640 billion potential labour hours in 2024.

Floods, droughts, and wildfires also take a severe toll. Flooding damages healthcare infrastructure, contaminates water supplies, and displaces populations. Droughts lead to food insecurity and malnutrition – in 2023, droughts and heatwaves were linked to an additional 124 million people facing moderate or severe food insecurity. Wildfires degrade air quality over vast areas and increase respiratory illness rates.

Infectious disease expansion 🔗

Warmer temperatures and changing rainfall patterns are expanding the geographic range of disease-carrying vectors like mosquitoes and ticks. Diseases such as malaria, dengue fever, and Lyme disease are emerging in areas where they were previously rare. Research published in Frontiers in Epidemiology noted that over 58% of known human diseases can be worsened by climate-related hazards, and deaths from vector-borne diseases – currently exceeding 700,000 annually – may rise further without preventive action.

Climate change is also exacerbating waterborne and foodborne illnesses. WHO data indicates that 2 billion people lack safe drinking water and 600 million suffer from foodborne illnesses annually, with climate stressors intensifying these risks.

Strategies to protect health from climate change 🔗

Addressing climate-driven health risks requires action on multiple fronts. The World Bank estimates that climate change could push an additional 132 million people into extreme poverty by 2030, with 44 million of those driven by health impacts alone. To counter this, health systems need climate-informed surveillance, early warning systems, and climate-resilient infrastructure.

Transitioning to low-carbon healthcare delivery is equally important – the health sector itself accounts for about 5% of global greenhouse gas emissions. Investing in clean energy, sustainable transport, and healthier food systems delivers co-benefits for both climate and health.

Water contamination and disease 🔗

Access to safe drinking water remains one of the most critical environmental determinants of health. Contaminated water is a leading cause of preventable disease, particularly in low-income countries.

The scale of the crisis 🔗

Despite progress, the global water situation remains alarming. The latest WHO/UNICEF Joint Monitoring Programme report (2025) found that 2.1 billion people still lack safely managed drinking water, including 106 million who drink directly from untreated surface sources like rivers and lakes. Additionally, 3.4 billion people lack safely managed sanitation, and 354 million still practice open defecation.

Contaminated water and poor sanitation are directly linked to the spread of cholera, dysentery, hepatitis A, and typhoid. Every year, approximately 361,000 children under five die from diarrhoea – a condition largely preventable with clean water and basic hygiene. People in the least developed countries are more than twice as likely to lack basic water and sanitation services compared to those in other nations.

Chemical contamination of water 🔗

Beyond biological pathogens, chemical contamination poses a serious threat. UNICEF reports that millions of people worldwide drink water containing arsenic or fluoride at levels the WHO considers unsafe. Industrial runoff, agricultural chemicals, and improper waste disposal introduce heavy metals, pesticides, and other toxins into water sources. Currently, around 80% of global wastewater is discharged without adequate treatment, contaminating freshwater supplies and ecosystems.

The effects of climate change are compounding the water quality problem, particularly in water-scarce regions and areas prone to flooding, where contamination risks spike during extreme weather events.

Improving water quality and sanitation 🔗

Between 2015 and 2024, 961 million people gained access to safely managed drinking water, raising global coverage from 68% to 74%. However, this progress is unevenly distributed. Rural areas in low-income countries lag significantly behind urban centres, and fragile or conflict-affected contexts face the widest gaps.

Solutions include investing in water treatment infrastructure, strengthening sanitation systems, implementing water safety plans at the community level, and using affordable monitoring technologies. The United Nations highlights that every dollar invested in improved sanitation generates an average global economic return of $5.50 – making it one of the most cost-effective public health interventions available.

Chemical exposure and toxicity 🔗

The modern world runs on chemicals. They are in our food, our consumer products, our workplaces, and our homes. While many chemicals are useful, poor management and inadequate regulation expose billions of people to harmful substances every day.

Persistent organic pollutants and industrial chemicals 🔗

A comprehensive UNEP-led study across 42 countries found persistent organic pollutants (POPs) present in every one of over 900 collected samples – in air, water, soil, human milk, meat, eggs, and fish. POPs are chemicals that persist in the environment for decades, accumulate in living organisms, and travel long distances through air and water currents. They are linked to cancer, endocrine disruption, reproductive harm, and birth defects.

The global chemical industry was valued at approximately $5 trillion in 2017 and is projected to double in size by 2030. This rapid growth, combined with weak enforcement in many countries, means that hazardous chemicals continue to be released in large quantities. Lead exposure alone was linked to an estimated 5.5 million heart disease deaths globally in 2019.

Vulnerable populations 🔗

Exposure to hazardous chemicals is not uniform. Men, women, and children encounter different types and levels of chemical exposure depending on their occupations, living conditions, and biology. Children are particularly vulnerable – their developing bodies absorb chemicals more readily, and exposure during critical growth periods can lead to lasting neurological and developmental damage. Workers in agriculture, manufacturing, and mining face elevated occupational risks, especially in countries with limited workplace safety standards.

Regulation and sustainable practices 🔗

International efforts to manage chemical risks are evolving. The Global Framework on Chemicals, adopted in 2023, provides an overarching structure for countries to collaborate on reducing harm from chemicals and waste. The Stockholm Convention continues to phase out the most dangerous POPs, now covering 34 chemicals. And the Basel, Rotterdam, and Stockholm Conventions collectively set standards for the handling and disposal of hazardous substances across borders.

However, a chemical-by-chemical regulatory approach cannot keep pace with the thousands of new substances entering commerce each year. Experts are calling for a shift toward green and sustainable chemistry – designing products and processes that minimize toxicity from the outset rather than managing harm after the fact. Strengthening monitoring systems in low- and middle-income countries, where data gaps are widest, is also essential for informed decision-making.

A connected challenge requiring integrated solutions 🔗

Air pollution, climate change, water contamination, and chemical exposure are not isolated problems. They interact and amplify each other. Industrial emissions pollute the air while releasing greenhouse gases that drive climate change. Rising temperatures worsen air quality and expand the range of waterborne and vector-borne diseases. Chemical runoff from agriculture contaminates drinking water, while climate-driven floods spread those contaminants further.

This interconnectedness means that effective solutions must also be integrated. Policies that reduce fossil fuel use, for example, simultaneously improve air quality and slow climate change. Investing in clean water and sanitation protects against both infectious disease and chemical exposure. Transitioning to green chemistry reduces pollution at its source rather than treating its effects downstream.

At the individual level, awareness matters. Understanding the environmental risks around us – and the policy choices that shape them – empowers communities to advocate for cleaner air, safer water, and stricter chemical regulation.

What do you think? Which environmental health risk do you believe deserves more urgent attention in your community – air pollution, water contamination, or chemical exposure? And how can individuals and local governments work together to reduce these risks effectively?

References

1. https://www.who.int/teams/environment-climate-change-and-health/air-quality-energy-and-health/health-impacts
2. https://www.who.int/news-room/commentaries/detail/air-pollution–tackling-a-critical-driver-of-the-global-ncd-crisis
3. https://www.who.int/europe/news-room/events/item/2025/05/20/default-calendar/annual-meeting-of-the-joint-task-force-on-health-aspects-of-air-pollution-(2025)
4. https://www.who.int/news/item/29-10-2025-climate-inaction-is-claiming-millions-of-lives-every-year–warns-new-lancet-countdown-report
5. https://www.frontiersin.org/journals/epidemiology/articles/10.3389/fepid.2025.1605058/full
6. https://www.who.int/news-room/fact-sheets/detail/climate-change-and-health
7. https://www.worldbank.org/en/topic/health/brief/health-and-climate-change
8. https://www.who.int/news/item/26-08-2025-1-in-4-people-globally-still-lack-access-to-safe-drinking-water—who–unicef
9. https://www.unicef.org/wash/water
10. https://www.un.org/en/global-issues/water
11. https://www.unep.org/gef/news-and-stories/press-release/some-chemical-pollutants-reducing-humans-and-environment-new-ones
12. https://www.unep.org/topics/chemicals-and-pollution-action
13. https://www.unep.org/global-framework-chemicals/framework/text-global-framework-chemicals