Health And The Climate Crisis: A Canadian Perspective for MCCQE1

Introduction

The intersection of Health and the Climate Crisis is an increasingly vital component of the MCCQE1 and the Public Health curriculum. For Canadian medical graduates, understanding the specific environmental challenges facing Canada—from wildfires in the West to vector-borne disease expansion in the East and rapid warming in the North—is essential.

This topic integrates closely with the CanMEDS Health Advocate role. Physicians are expected to recognize environmental determinants of health and advocate for sustainable healthcare practices.

The Spectrum of Climate Health Impacts

Climate change acts as a “threat multiplier,” exacerbating existing health issues and introducing new ones. The impacts are generally categorized into direct, indirect, and health system impacts.

1. Direct Physical Health Impacts

Extreme Heat Events

Canada is experiencing more frequent and intense heatwaves (e.g., the 2021 Western North America heat dome).

Extreme Weather Events

• Wildfires: Increased incidence in British Columbia, Alberta, and the Boreal forest.
  • Health Risk: PM2.5 inhalation leading to exacerbations of Asthma and COPD.
  • Acute Effects: Eye irritation, bronchitis, reduced lung function.
• Floods: Increased risk in Manitoba and coastal regions.
  • Health Risk: Waterborne diseases, mold exposure, injury, displacement.

2. Ecological and Indirect Impacts

Vector-Borne Diseases

Changing climates allow vectors to survive in previously inhospitable Canadian latitudes.

Air Quality

Ground-level ozone and particulate matter (PM) increase with higher temperatures and stagnant air masses.

• Cardiovascular: Increased risk of MI, stroke, and arrhythmias.
• Respiratory: Increased ED visits for respiratory distress.

3. Mental Health Impacts

Vulnerable Populations in Canada

Climate change does not affect all Canadians equally. Understanding these disparities is crucial for the PHELO component of the MCCQE1.

Indigenous Communities

• Northern Canada: Warming at 2x to 3x the global rate.
• Impacts: Melting permafrost affects housing stability; changing ice patterns affect traditional hunting/gathering (food insecurity); loss of cultural practices.

The Elderly and Socially Isolated

• Highest mortality during heatwaves (e.g., Montreal 2018, BC 2021).
• Risk factors: Lack of air conditioning, limited mobility, polypharmacy (anticholinergics/diuretics affecting thermoregulation).

Low Socioeconomic Status (SES)

• Often live in “Urban Heat Islands” with less green space.
• Less capacity to adapt (e.g., afford AC or air filtration).

Canadian Guidelines and Monitoring Tools

Familiarity with these tools is expected for Canadian medical practice.

Air Quality Health Index (AQHI)

Unlike the old AQI, the Canadian AQHI measures the health risk associated with air pollution on a scale of 1-10+.

• 1-3 (Low Risk): Enjoy outdoor activities.
• 4-6 (Moderate Risk): Consider reducing or rescheduling strenuous activities outdoors if you are experiencing symptoms.
• 7-10 (High Risk): At-risk populations should reduce or reschedule strenuous outdoor activities.
• 10+ (Very High Risk): Everyone should avoid strenuous outdoor activities.

Heat Alert and Response Systems (HARS)

Health Canada and provincial bodies issue alerts based on region-specific thresholds.

Clinical Management and Mitigation

The “Green” Physician

The Canadian healthcare system contributes approximately 4.6% of the country’s total greenhouse gas emissions.

Abbreviations Checklist

AQHI  : Air Quality Health Index
GHG   : Greenhouse Gas
HARS  : Heat Alert and Response Systems
MDI   : Metered Dose Inhaler
DPI   : Dry Powder Inhaler
PM2.5 : Particulate Matter <2.5 micrometers
VOC   : Volatile Organic Compounds

Key Points to Remember for MCCQE1

• Heat Stroke vs. Heat Exhaustion: The defining feature of heat stroke is CNS dysfunction (confusion, ataxia) and core temp usually >40°C.
• Lyme Disease: Know the geography (expanding) and the rash (Erythema Migrans). It is a clinical diagnosis in the early stage; do not wait for serology to treat.
• Vulnerability: Indigenous populations in the North face the most rapid climate changes affecting food security and infrastructure.
• Co-benefits: Interventions that help the climate often help the patient (e.g., active transport reduces obesity and emissions; plant-rich diets reduce cardiac risk and land use).
• AQHI: Know the advice for “At-Risk” populations (elderly, children, those with pre-existing conditions) during High Risk (7-10) periods.

Sample Question

Clinical Scenario

A 78-year-old man is brought to the Emergency Department by his daughter during a prolonged heatwave in July. The daughter reports that she went to check on him because he wasn’t answering the phone. She found him confused and lethargic in his apartment, which does not have air conditioning. He has a history of hypertension and schizophrenia. His medications include hydrochlorothiazide and olanzapine.

On examination, he is stuporous and responds only to painful stimuli. His skin is hot and dry. Vital signs are:

• BP: 95/60 mmHg
• HR: 120 bpm
• RR: 24/min
• Rectal Temperature: 40.8°C (105.4°F)
• O2 Sat: 96% on room air

Which of the following is the most appropriate immediate management step?

Options

• A. Administer 650 mg acetaminophen per rectum.
• B. Initiate broad-spectrum antibiotics after drawing blood cultures.
• C. Perform total body immersion in cold water.
• D. Infuse 2L of normal saline rapidly.
• E. Order a CT scan of the head to rule out stroke.

Explanation

The correct answer is:

• C. Perform total body immersion in cold water.

Detailed Analysis

Diagnosis: This patient is presenting with Classic Non-Exertional Heat Stroke. The key diagnostic criteria present are:

1. Hyperthermia: Core temperature >40°C.
2. CNS Dysfunction: Altered mental status (stuporous).
3. Context: Heatwave, elderly, lack of AC.
4. Risk Factors: Medications that impair thermoregulation (Olanzapine affects central thermoregulation; Hydrochlorothiazide causes volume depletion). Anhidrosis (hot, dry skin) is common in classic heat stroke (vs. exertional where sweating may persist).

• Option C: Rapid cooling is the cornerstone of therapy and the strongest predictor of survival. The goal is to reduce the core temperature to 38-39°C within 30 minutes. Cold water immersion (or ice water slurry) is the most effective method for rapid conduction of heat away from the body.

• Option A (Acetaminophen): Antipyretics are contraindicated in heat stroke. The pathophysiology involves thermal dysregulation, not a change in the hypothalamic set point (as in fever). They can exacerbate hepatic injury.
• Option B (Antibiotics): While sepsis is a differential, the history strongly suggests environmental heat stroke. Delaying cooling to work up sepsis is dangerous.
• Option D (IV Fluids): While the patient is likely dehydrated, rapid cooling takes precedence. Aggressive fluid resuscitation in the elderly can lead to pulmonary edema. Fluids should be given cautiously after or during cooling.
• Option E (CT Head): While a stroke is on the differential for altered mental status, the extreme hyperthermia makes heat stroke the primary working diagnosis. Transporting an unstable, hyperthermic patient to CT delays the critical intervention (cooling).

References

1. Health Canada. (2023). Health Facilities and Services: Climate Change and Health. Government of Canada.
2. Canadian Association of Physicians for the Environment (CAPE). (2022). Climate Change Toolkit for Health Professionals.
3. Public Health Agency of Canada. (2023). Lyme disease: For health professionals.
4. Cheng, J. J., & Berry, P. (2013). Health co-benefits and risks of public health adaptation strategies to climate change: a review of current literature. International Journal of Public Health.
5. Royal College of Physicians and Surgeons of Canada. CanMEDS 2015 Physician Competency Framework.