# Climate Change and Health Across the Lifespan

## Introduction

Climate change is a **health emergency** with profound implications across the lifespan. Children, pregnant women, older adults, and those with chronic diseases are disproportionately vulnerable. Rising temperatures, extreme weather events, air pollution, vector-borne disease expansion, and food insecurity are already causing measurable health effects worldwide. Med-peds physicians must understand the mechanisms through which climate change affects human health, recognize climate-sensitive conditions, and advocate for mitigation and adaptation strategies.

## Climate Change and Human Health: Pathways

### Direct Effects

**Extreme heat**: Heat exhaustion, heat stroke, exacerbation of cardiovascular and renal disease. **Extreme weather events**: Hurricanes, floods, and wildfires cause injuries, displacement, and mental health trauma. **Wildfires**: Particulate matter (PM2.5) exposure causes acute respiratory exacerbations and long-term cardiovascular risk. **Drought**: Water scarcity affecting hygiene, agriculture, and nutrition.

### Indirect Effects

**Air quality degradation**: Ground-level ozone and PM2.5 from fossil fuel combustion worsen asthma, COPD, and cardiovascular disease. **Allergen changes**: Longer pollen seasons and higher pollen counts increase allergic disease burden. **Vector-borne disease expansion**: Warming temperatures expand geographic range of mosquitoes (dengue, Zika, malaria) and ticks (Lyme disease) **Food insecurity**: Crop failures, fishery decline, and nutritional quality reduction from elevated CO2. **Water-borne disease**: Flooding increases contamination; warming favors Vibrio and harmful algal blooms. **Mental health**: Eco-anxiety, climate grief, PTSD from extreme events, and displacement.

![Pathways linking climate change to health outcomes across the lifespan](illustration-climate-health-pathways.jpg)

## Vulnerable Populations Across the Age Spectrum

| Population | Key Vulnerabilities | Primary Climate Threats | Clinical Considerations |
|-----------|-------------------|----------------------|------------------------|
| Children | Immature thermoregulation; developing organs; high metabolic rate | Heat illness, asthma from air pollution, vector-borne disease | Sports safety protocols; asthma action plans with AQI triggers |
| Pregnant women | Altered thermoregulation; fetal vulnerability | Preterm birth, preeclampsia, stillbirth | Heat avoidance counseling; air quality monitoring |
| Older adults | Impaired thermoregulation; polypharmacy; social isolation | Heat stroke, cardiovascular events, respiratory exacerbations | Medication review (diuretics, anticholinergics); welfare checks |
| Chronic disease | Impaired adaptive capacity | Disease exacerbation, medication instability | Insulin storage plans; inhaler action plans; hydration counseling |

### Children

Children are **disproportionately vulnerable** due to higher metabolic rates, immature organ systems, behavioral patterns, and longer time horizon for cumulative exposures. **Heat-related illness**: Children thermoregulate less efficiently; sports-related heat illness is increasing. **Asthma exacerbations**: Air pollution and allergen increases drive emergency visits; asthma is already the leading cause of pediatric chronic disease. **Infectious disease**: Diarrheal diseases increase with flooding and water contamination; vector-borne diseases expand into new regions. **Malnutrition**: Climate-driven food insecurity affects growth and neurodevelopment. **Mental health**: Children and adolescents experience eco-anxiety, climate grief, and trauma from displacement. **Developmental effects**: Prenatal air pollution exposure is associated with low birth weight, preterm birth, and neurodevelopmental disorders.

### Pregnant Women

Heat exposure increases risk of **preterm birth, low birth weight, and stillbirth**. Air pollution (PM2.5, ozone) is associated with gestational hypertension and preeclampsia. Climate-driven food insecurity affects maternal nutrition and fetal growth. Infectious disease expansion (Zika virus) poses teratogenic risks.

### Older Adults

**Heat vulnerability**: Impaired thermoregulation, chronic disease burden, polypharmacy (diuretics, anticholinergics reduce heat adaptation) Social isolation amplifies heat risk; the 2003 European heat wave killed an estimated 70,000, predominantly elderly. **Cardiovascular and respiratory exacerbations** from air pollution and extreme temperatures. Displacement from extreme weather events is particularly disruptive for older adults with mobility limitations and care needs.

### Chronic Disease Populations

**Asthma and COPD**: Worsened by air pollution, allergens, and wildfire smoke. **Cardiovascular disease**: Heat stress increases cardiac workload; PM2.5 is an independent cardiovascular risk factor. **Diabetes**: Heat impairs insulin storage and glucose regulation; food insecurity disrupts dietary management. **Kidney disease**: Dehydration and heat stress exacerbate CKD; "Mesoamerican nephropathy" linked to occupational heat exposure. **Mental illness**: Lithium toxicity risk increases with dehydration; heat-related psychiatric emergencies increase during heat waves.

## Clinical Implications

### Heat-Related Illness

**Heat exhaustion**: Core temperature 37-40 degrees C; fatigue, headache, nausea, diaphoresis; treat with cooling and hydration. **Heat stroke**: Core temperature >40 degrees C with altered mental status; medical emergency requiring aggressive cooling (cold water immersion, evaporative cooling) Pediatric dosing for IV rehydration; adult management includes ICU-level monitoring for organ dysfunction. Prevention: Hydration, acclimatization, avoiding exertion during peak heat, checking on elderly during heat waves.

### Air Quality and Respiratory Health

Monitor **Air Quality Index (AQI)** and advise patients to limit outdoor activity when AQI >100. Asthma action plans should incorporate air quality triggers. N95 masks provide protection from wildfire smoke particulate matter. Long-term PM2.5 exposure is associated with reduced lung development in children and accelerated lung function decline in adults.

### Vector-Borne Disease Surveillance

Expanding ranges of **Aedes aegypti** and **Aedes albopictus** mosquitoes bring dengue, Zika, and chikungunya to previously unaffected regions. **Tick-borne diseases**: Lyme disease expanding northward and to higher altitudes; longer tick seasons. Clinicians in newly affected areas must maintain awareness and diagnostic capability.

![Climate-sensitive conditions presenting across pediatric and adult practice](illustration-climate-sensitive-conditions.jpg)

## Physician Advocacy and Healthcare Sustainability

The healthcare sector contributes **4.4% of global greenhouse gas emissions**; hospitals and health systems have a responsibility to reduce their carbon footprint. **Prescribing practices**: Metered-dose inhalers have a significantly higher carbon footprint than dry powder inhalers; consider when clinically equivalent. **Telemedicine**: Reduces patient travel and associated emissions. **Sustainable hospital practices**: Energy efficiency, waste reduction, local food sourcing. Physician advocacy for clean energy policy, air quality standards, and climate adaptation infrastructure. Medical education should integrate climate and health curriculum.

![Healthcare system strategies for climate mitigation and adaptation](illustration-healthcare-climate-strategies.jpg)

## Clinical Pearls

Children are the most vulnerable population to climate change health effects due to physiologic, developmental, and exposure factors. Heat stroke is a medical emergency; rapid cooling to below 39 degrees C within 30 minutes improves survival. Air pollution is a leading environmental risk factor for disease globally; anticipatory guidance on AQI monitoring should be routine. Vector-borne disease geographic ranges are expanding; clinicians must maintain awareness of emerging local risks. Physicians have a professional obligation to advocate for climate policies that protect health and reduce healthcare's carbon footprint.

## References

1. Watts N, Amann M, Arnell N, et al. The 2020 report of The Lancet Countdown on health and climate change. *Lancet*. 2021;397(10269):129-170.
2. Perera FP. Multiple threats to child health from fossil fuel combustion: Impacts of air pollution and climate change. *Environ Health Perspect*. 2017;125(2):141-148.
3. Salas RN, Shultz JM, Solomon CG. The climate crisis and clinical practice. *N Engl J Med*. 2020;382(7):589-591.
4. Ebi KL, Capon A, Berry P, et al. Hot weather and heat extremes: Health risks. *Lancet*. 2021;398(10301):698-708.