Climate change is exacerbating diseases in vulnerable populations in America and abroad

Climate change is often framed as a problem for polar bears and future generations.
In reality, it’s a right-now problem for people whose air, water, homes, and jobs are
already on the edge. Rising temperatures, choking wildfire smoke, bigger storms, and
shifting disease patterns are all combining into a health crisis that lands hardest on
those with the fewest resources to cope.

From low-income neighborhoods in Phoenix baking under extreme heat to communities in
South America facing surges of dengue fever, climate change is amplifying existing
health inequities. Vulnerable populations in America and abroad aren’t just dealing
with “bad weather” they’re facing higher rates of asthma attacks, heart problems,
mental health strain, and infectious disease outbreaks that are directly linked to a
warming world.

Climate change and human health: more than just hotter summers

The science is now painfully clear: climate change affects health through multiple
pathways. It intensifies extreme heat, worsens air pollution, fuels wildfires, shifts
where disease-carrying insects can live, and increases heavy rainfall and flooding.
Each of these pathways has its own set of health risks, many of which cluster in
communities that are already socially or economically stressed.

Direct hits: heat waves, storms, and floods

Heat is one of the clearest and deadliest climate signals. Heat waves are becoming
longer, more frequent, and more intense in the United States and globally. For older
adults, people with heart or kidney disease, people who work outdoors, and those who
can’t afford air conditioning, these hot days are not just uncomfortable they can
trigger heat exhaustion, heat stroke, heart attacks, and premature death.

Extreme storms and floods linked to a warmer atmosphere also worsen disease risk.
Hurricanes and heavy rainfall can contaminate drinking water, disrupt healthcare
services, increase mold and indoor air problems, and set the stage for outbreaks of
waterborne illnesses. People living in low-lying coastal areas, informal settlements,
or poorly maintained housing are much more likely to face serious health consequences
when these events hit.

Indirect impacts: air, smoke, allergens, and mental health

Climate change is also turbocharging air pollution. Hotter days increase the formation
of ground-level ozone (smog), which irritates the lungs and worsens asthma and chronic
obstructive pulmonary disease (COPD). Longer and more intense wildfire seasons send
plumes of fine particulate matter (PM2.5) across regions, inflaming airways, raising
cardiovascular risk, and sending vulnerable people to emergency rooms.

Allergy seasons are getting longer as warmer temperatures and higher carbon dioxide
levels encourage certain plants to produce more pollen. That means more sneezing,
wheezing, and missed school or work days for people with allergic asthma or hay fever.
And on top of the physical impacts, climate-related disasters and chronic stressors
contribute to anxiety, depression, post-traumatic stress, and a general sense of
uncertainty about the future again, felt most intensely by communities with fewer
buffers.

Who is most vulnerable in America?

Not everyone in the United States is equally exposed to climate-related health risks.
The same social and economic factors that drive health disparities such as racism,
poverty, inadequate housing, and lack of access to healthcare also shape who gets hit
hardest by climate change.

Low-income communities and communities of color

Historically redlined neighborhoods, often home to Black, Latino, and immigrant
communities, tend to have fewer trees, more pavement, and older housing. That
combination creates urban heat islands where temperatures can be several degrees
hotter than in greener, wealthier neighborhoods across town. Residents are more likely
to live in buildings without adequate insulation or cooling, and less likely to afford
higher energy bills during heat waves.

These same communities are frequently located closer to highways, industrial zones,
and ports, increasing exposure to air pollution that drives asthma and cardiovascular
disease. Add wildfire smoke drifting in from hundreds of miles away, and you have
overlapping layers of respiratory stress that show up as higher ER visits and hospital
admissions in already disadvantaged populations.

Children, older adults, and people with chronic illness

Children breathe faster, spend more time outdoors, and have developing lungs, which
makes them especially sensitive to dirty air and extreme heat. Childhood asthma is
closely tied to air pollution, and climate-driven increases in ozone and fine particles
can make symptoms more frequent and severe. For a kid in a low-income family, an asthma
attack doesn’t just mean a rescue inhaler it can mean missed school, worried parents,
and medical bills that strain the household budget.

Older adults and people living with heart disease, diabetes, kidney disease, or lung
conditions are also at higher risk. Heat waves and smoke events can push already
fragile systems over the edge, triggering heart attacks, strokes, dehydration, and
acute breathing problems. When these events coincide with power outages or overwhelmed
healthcare systems, outcomes can be especially grim.

Rural communities, farmworkers, and Tribal nations

In rural America, climate change can look like prolonged drought that harms crops, or
intense storms that wipe out harvests and contaminate wells. Farmworkers and other
outdoor laborers, many of whom are migrants or low-wage workers, face high levels of
heat stress and pesticide exposure. Protective policies and enforcement are often
inadequate, leaving workers to choose between their paycheck and their health.

Tribal communities often have deep cultural and livelihood ties to the land and water.
Changes in temperature, precipitation, and wildlife patterns threaten not only food
sources and economic stability but also spiritual traditions and mental well-being.
Limited infrastructure, underfunded healthcare, and historic marginalization compound
the health impacts of floods, wildfires, and ecosystem shifts.

Diseases on the move across a warming planet

Climate change doesn’t respect borders. As temperatures rise and rainfall patterns
shift, the habitats of disease vectors such as mosquitoes and ticks are changing.
That means illnesses like dengue, malaria, West Nile virus, and Lyme disease are
appearing in new places or extending their seasonal reach.

Vector-borne diseases: mosquitoes and ticks expand their range

Warmer temperatures can speed up mosquito life cycles and viral replication, making it
easier for diseases like dengue, chikungunya, and Zika to spread. In parts of South
America and the Caribbean, record-breaking dengue outbreaks have coincided with heat
waves, heavy rains, and rapid urban growth. Vulnerable populations such as people
living in informal settlements with poor sanitation and limited access to healthcare
bear the brunt of these outbreaks.

In the United States and Europe, warmer conditions and changing precipitation patterns
are aiding the spread of ticks that carry Lyme disease and other infections. Rural and
suburban communities with lots of edge habitats (where people, pets, and wildlife mix)
are especially exposed. People who work outdoors, lack access to bug repellent, or have
limited healthcare access face greater risks of delayed diagnosis and complications.

Waterborne and foodborne diseases

Heavy rainfall, flooding, and storm surges increase the risk of contaminated drinking
water and sewage overflows. This can lead to outbreaks of diarrheal diseases in
communities that rely on compromised water systems or lack robust sanitation
infrastructure. Coastal warming can also boost harmful algal blooms, raising the risks
of seafood contamination and skin or respiratory irritation for people who fish, swim,
or live near affected shorelines.

In many low- and middle-income countries, climate-sensitive water and food systems mean
that vulnerable groups such as children, pregnant women, and people in poverty are
more likely to experience malnutrition, stunting, and infections that undermine long-
term health and development.

Noncommunicable diseases under climate stress

It’s not just infectious diseases that are affected. Noncommunicable diseases (NCDs)
like heart disease, stroke, diabetes, and respiratory conditions are highly sensitive
to climate stressors. Heat can worsen blood pressure control and place extra strain on
the heart and kidneys. Air pollution whether from vehicles, power plants, or
wildfires increases the risk of heart attacks and strokes, especially in people who
are already at high risk.

People living with NCDs often need regular medications, stable housing, refrigeration,
and reliable access to healthcare. When climate-related disasters disrupt electricity,
supply chains, or clinic operations, these patients can quickly find themselves in
dangerous territory. Once again, the heaviest burden falls on those with limited
savings, limited insurance, and limited political voice.

Real-world examples of climate, disease, and inequality

Heat, smoke, and chronic disease in the United States

Imagine a summer day in a low-income neighborhood in California’s Central Valley. The
temperature tops 105°F, the air is thick with wildfire smoke from a blaze two counties
away, and an older resident with diabetes and heart disease lives in an apartment with
no central AC. The nearest cooling center is miles away and requires a car she doesn’t
have. That mix of heat stress, fine particle pollution, and chronic illness is exactly
how climate change turns into preventable hospitalizations and premature deaths.

Or consider a child in a dense urban neighborhood asthma-prone from early-life exposure
to traffic pollution. On days when heat and air quality alerts overlap, their risk of
wheezing, using a rescue inhaler, or ending up in the ER spikes. Families with flexible
jobs, air conditioning, and good healthcare can buffer these shocks; families without
those advantages face a very different level of risk.

Dengue, flooding, and fragile health systems abroad

In parts of South America and Southeast Asia, intense rains and warmth create ideal
breeding grounds for mosquitoes. When dengue cases surge, clinics overflow, blood
supplies run low, and people with limited transportation or money may not receive
timely care. Vulnerable populations including those living in crowded urban slums,
residents of remote rural communities, and people displaced by conflict or disasters
are at heightened risk of severe disease and death.

In low-lying coastal regions and small island states, sea-level rise and stronger
storms are salting freshwater supplies and damaging health facilities. After major
cyclones or typhoons, outbreaks of diarrheal disease, skin infections, and vector-
borne illnesses frequently follow. Healthcare workers are left to manage emergencies
while also grappling with damaged infrastructure and limited resources.

Reducing climate-related disease risks: what actually helps?

Building climate-resilient, health-centered communities

The encouraging news: many of the strategies that cut climate pollution also make
communities healthier right now. Expanding tree cover and green spaces in overheated
neighborhoods can bring down temperatures, improve air quality, and provide safe
places to be active. Upgrading housing to be energy efficient and better insulated
keeps homes cooler in summer and warmer in winter, while lowering energy bills.

Investing in public health infrastructure from early warning systems for heat waves
to robust disease surveillance helps catch problems early. Cooling centers, clean air
shelters, and targeted outreach to people at highest risk can turn dangerous weather
events into manageable challenges instead of full-blown crises.

Cutting emissions with big health co-benefits

Reducing greenhouse gas emissions isn’t just about stabilizing the climate decades
from now; it also delivers immediate health benefits. Shifting to clean energy,
improving public transit, and encouraging walking and cycling all reduce harmful air
pollution that drives asthma and heart disease. Cleaner air means fewer hospital
visits, fewer missed work days, and lower healthcare costs especially for vulnerable
populations that currently inhale the most pollution.

Climate policies that prioritize equity for example, investments in clean energy and
transportation in historically overburdened neighborhoods can correct long-standing
environmental injustices while reducing climate-related disease risks.

What individuals and local leaders can do

On a personal level, people can protect themselves and their families by staying
informed about heat and air quality alerts, creating cool and clean-air spaces at
home if possible, checking on neighbors who might be isolated, and using
evidence-based mosquito protection measures in high-risk areas. Healthcare providers
can incorporate climate-sensitive risks into routine care, such as reminding patients
with heart or lung disease to take extra precautions on high-heat or high-smoke days.

Local leaders from city councils to school boards play a crucial role. They can
prioritize tree planting in the hottest neighborhoods, support resilient water and
energy systems, invest in active transportation, and ensure that emergency plans
explicitly address the needs of populations at highest risk, including people with
disabilities, non–English speakers, and those without stable housing.

Experiences from the front lines of climate and disease

Statistics and graphs are important, but the reality of climate change and disease is
best understood through lived experience. Around the United States and across the
globe, people are already navigating health challenges shaped by climate disruptions.

Picture a community health nurse in southern Arizona. Ten years ago, summer home visits
for older patients meant reminding them to stay hydrated and take their medications.
Now, she plans her rounds around extreme heat alerts, checking on seniors who live
alone in older mobile homes with thin walls and unreliable air conditioning. She
carries portable fans and extra water, and she has learned to watch for early signs of
heat exhaustion in people whose chronic conditions leave them less able to cope with
soaring temperatures. Some days, she feels more like a disaster responder than a
primary care nurse.

In a small town in the Pacific Northwest, a pediatrician has watched “smoke season”
become a regular entry on the calendar. When wildfires ignite hundreds of miles away,
the sky turns hazy, the playground empties, and parents ask whether it’s safe to let
their kids outside. The pediatrician now keeps a stack of handouts about air purifiers,
window-sealing tips, and how to adjust asthma action plans during smoke events. For
families who can’t afford air filters or who live in crowded apartments with drafty
windows, the advice is harder to follow and the doctor knows that their children
will likely be back with worsening symptoms.

Thousands of miles away, a community health worker in a low-income neighborhood of a
Latin American city leads workshops on mosquito control. Residents are dealing with
intermittent water supplies, so they store water in buckets and barrels perfect
breeding sites for Aedes mosquitoes that spread dengue and other viruses. Warmer,
wetter seasons have made outbreaks more frequent. The community worker teaches people
how to cover containers, use simple larvicides where appropriate, and recognize early
symptoms of severe dengue. She also hears their worries about missing work if they
fall ill, about overcrowded clinics, and about the next heavy rain that might flood
their homes.

In a coastal village threatened by sea-level rise, elders describe how fishing grounds
have shifted and storms have become more unpredictable. Younger residents consider
whether they should leave to find work elsewhere. When a major storm damages the
local health post, routine vaccinations and prenatal care are disrupted for months.
People with chronic conditions like hypertension or diabetes struggle to refill
prescriptions. For this community, climate change is not an abstract policy debate;
it’s a daily question of whether they can safely drink the water, get to the clinic,
or keep their livelihoods.

These stories, though simplified, capture a shared pattern: climate change magnifies
existing vulnerabilities. The same structural issues poverty, discrimination,
underfunded public services, and fragile health systems determine who can adapt and
who gets left behind. Listening to those at the front lines, and investing in solutions
that center their needs, is essential if we want a future where a changing climate does
not automatically translate into more disease and deeper inequality.

Ultimately, the fact that climate change is exacerbating diseases in vulnerable
populations is not just a scientific finding; it is a moral decision point. Societies
can choose to let existing inequities deepen as the planet warms, or they can use this
moment to build cleaner, fairer, and healthier communities for everyone in America
and around the world.