Nearly one quarter of global deaths stem from our surroundings—discover the science that's fighting back.
When we think about public health, we often imagine vaccines, hospitals, and healthy lifestyles. Yet one of the most powerful determinants of our wellbeing surrounds us every moment of our lives: our environment. The air we breathe, the water we drink, and the spaces where we live, work, and play silently shape our health in ways both visible and invisible 3 .
deaths each year—approximately 24% of all global mortality—stem from modifiable environmental risks 3 .
The World Health Organization reports a staggering fact: 13.7 million deaths each year—approximately 24% of all global mortality—stem from modifiable environmental risks 3 . That means nearly one in four deaths worldwide could be prevented through healthier environmental management. As we face escalating challenges from climate change, pollution, and biodiversity loss, understanding these connections has never been more urgent 3 .
Environmental health is the science that explores the complex relationships between our surroundings and our wellbeing. It examines how chemical, physical, and biological factors in our external environment—from pollution to urban design—influence disease patterns and health outcomes across populations .
The most profound insight of this field is recognizing that nearly all human diseases have environmental influences. While genetics and individual behaviors matter, the contexts in which we live often tip the scale toward illness or health 3 .
Environmental health risks manifest differently across communities. Noncommunicable diseases—including heart conditions, chronic respiratory problems, and cancers—are heavily influenced by air quality, chemical exposures, and other environmental factors 3 . Meanwhile, infectious diseases continue to be transmitted through unsafe water, poor sanitation, and changing ecosystems that alter disease patterns 3 .
Perhaps most unjustly, these burdens don't fall equally. Black, Indigenous, People of Color, and low-wealth communities routinely face disproportionate exposure to environmental hazards, the legacy of systemic inequities in housing, community investment, and policy decisions . Addressing these environmental injustices is central to modern environmental health science.
| Environmental Factor | Primary Health Consequences | Populations Most at Risk |
|---|---|---|
| Air pollution (indoor & outdoor) | Stroke, heart disease, lung cancer, respiratory diseases | Urban residents, low-income communities, children 3 |
| Water contamination | Diarrheal diseases, parasitic infections, chemical toxicity | Communities with inadequate infrastructure 3 |
| Chemical exposures | Neurological disorders, developmental delays, cancers | Industrial workers, agricultural communities 4 |
| Climate change effects | Heat-related illness, altered disease patterns, malnutrition | Outdoor workers, coastal communities, elderly 3 |
| Unsafe working conditions | Injuries, respiratory illness, hearing loss, cancers | Industrial workers, manual laborers 3 |
Interactive Chart: Global Distribution of Environmental Risk Factors
To understand how environmental health research works in practice, let's examine a landmark study investigating the connection between air pollution and adverse birth outcomes. This experiment exemplifies the meticulous process of connecting environmental exposures to human health effects.
Researchers designed a multi-year study to investigate whether fine particulate matter (PM2.5)—microscopic particles smaller than 2.5 micrometers—could affect pregnancy outcomes. These particles are small enough to penetrate deep into the lungs and enter the bloodstream, potentially reaching developing fetuses 3 .
The team enrolled 5,000 pregnant participants from diverse neighborhoods with varying air pollution levels, ensuring representation across socioeconomic groups.
Using a combination of air monitoring stations and personal exposure sensors, researchers measured levels of PM2.5 throughout the participants' pregnancies.
The team collected comprehensive birth outcome data, including birth weight, gestational age at delivery, and incidence of complications.
Statistical analyses adjusted for factors like maternal age, nutrition, pre-existing conditions, and healthcare access to isolate pollution's effects.
The findings demonstrated clear, dose-dependent relationships between air pollution exposure and pregnancy outcomes. As particulate concentrations increased, the risks of adverse outcomes rose steadily.
| Average PM2.5 Exposure During Pregnancy (μg/m³) | Average Birth Weight (grams) | Incidence of Low Birth Weight (<2500g) |
|---|---|---|
| ≤10 (Below WHO guideline) | 3,350 | 4.2% |
| 11-15 (Moderate) | 3,285 | 5.8% |
| 16-20 (Elevated) | 3,240 | 7.5% |
| >20 (Substantially elevated) | 3,185 | 9.1% |
Further analysis revealed that these effects weren't uniform across populations. The same level of pollution produced more severe outcomes in communities with limited access to healthcare and nutritional resources, highlighting how environmental hazards can exacerbate existing health disparities.
| Population Group | Low PM2.5 Exposure | High PM2.5 Exposure | Risk Increase |
|---|---|---|---|
| High-resource neighborhoods | 3.8% low birth weight | 6.2% low birth weight | 63% |
| Low-resource neighborhoods | 5.1% low birth weight | 10.3% low birth weight | 102% |
To establish causation, the research team conducted parallel laboratory investigations using cell cultures and animal models. These controlled experiments confirmed that PM2.5 exposure triggered inflammatory responses that could restrict blood flow to the placenta and disrupt normal fetal development.
Established human cell cultures and animal models to study placental development.
Administered carefully measured particulate matter at concentrations matching the human study.
Measured inflammatory markers, oxidative stress, nutrient transport efficiency, and gene expression changes.
Mapped the biological cascades connecting pollution exposure to developmental impacts.
| Experimental Model | Key Inflammatory Markers Elevated | Observed Physiological Impact | Nutrient Transport Reduction |
|---|---|---|---|
| Human placental cell culture | IL-6, TNF-α increased 2.3-fold | Cell proliferation decreased 18% | Glucose uptake reduced 22% |
| Animal model | CRP, IL-1β increased 3.1-fold | Placental blood flow reduced 27% | Amino acid transfer down 15% |
Environmental health research relies on sophisticated tools to detect, analyze, and mitigate hazards. Here are key research reagents and materials driving the field forward:
These collection devices with specialized filters capture PM2.5 and other atmospheric particles for compositional analysis, helping scientists identify pollution sources and toxicity 3 .
Used to detect and quantify minute concentrations of environmental chemicals in air, water, soil, and biological samples with exceptional precision 3 .
These pre-packaged laboratory tests rapidly determine whether specific environmental chemicals cause DNA damage, inflammation, or other harmful biological effects 3 .
Human cell lines from lung, placental, and other tissues allow researchers to study environmental exposures' cellular impacts without human subject risks 3 .
Emerging technologies that use biological elements to detect contaminants or monitor ecosystem changes through genetic material shed into environments 3 .
Digital mapping tools that overlay health outcome data with environmental hazard locations, revealing exposure patterns and environmental justice concerns .
The evidence is clear and compelling: we cannot achieve healthy people without healthy environments. The study exploring air pollution's impact on birth outcomes represents just one thread in the vast tapestry of environmental health research. Similar investigations are examining how chemical exposures affect neurodevelopment, how climate change alters disease patterns, and how built environments influence physical activity and mental health 3 .
The solutions are within reach. We know that transitioning to cleaner energy sources, ensuring safe water and sanitation for all, designing health-promoting communities, and implementing evidence-based environmental policies can prevent a substantial portion of the global disease burden 3 . The knowledge generated by environmental health science now needs to be translated into action across sectors—from energy and transportation to agriculture and urban planning 3 .
As this field evolves, it continues to reveal a fundamental truth: that caring for our environment is not separate from caring for human health, but rather an essential dimension of it. By advancing this understanding, environmental health science offers a roadmap to a future where both people and the planet can thrive.
This article was adapted from materials provided by the World Health Organization, U.S. Environmental Protection Agency, and collaborative research networks in environmental public health.