Written by Dr. Matt Douglas-Vail; edited by Navpreet Sahsi and Hiren Patel, June 2023

In 2015, the Lancet declared climate change as the biggest global health threat of the 21st century.1 In Canada, there is predicted to be increased powerful storms, floods, drought, wildfires and vector-borne diseases.2 Emergency physicians care for society’s most vulnerable patients and must prepare for climate-related emergencies and new migratory diseases.3 Emergency physicians must also recognize that climate change directly impacts the social and environmental determinants of health.4 In this article, we outline several ways Emergency Medicine in Canada is likely to be impacted by climate change.

Pandemics and climate change and the impending impact on EM

Emergency departments were especially hard hit by the Covid-19 pandemic. The influence of the environment on Covid-19 and the impact of Covid-19 on the environment are intimately linked. Air pollution around the world has been correlated with increased Covid-19 morbidity and mortality.5,6 In fact, one study found than an increased in PM2.5 by 1 ug per m3 increased Covid mortality by 8%.7 Public health measures in cities like Shanghai and Wuhan saw a dramatic decline in PM2.5.8 This group calculated that potentially 40,000 children under 5 years of age and 73,000 adults over 70 years of age may have been saved from climate-related deaths by this reduction in air pollution. This calculation demonstrates the potential benefit of drastic climate and air pollution policies. These findings suggest that climate change may potentiate further pandemics like Covid-19.7 As much as EDs should be prepared for future pandemics, we should also recognize the ways in which climate change are likely to shape and influence these pandemics.

Floods and storm surges impending impact on EM

Flooding also poses a significant challenge to EDs, creating the potential for mass casualty situations involving complicated prehospital and retrieval environments9 . The direct results of flooding include drowning, trauma and hypothermia. Following Hurricane Katrina, there was a surge in lacerations, open wounds, corneal abrasions and boat-related trauma presenting to local EDs.10 Following the storm surges of Hurricane Andrew in 1992, there was a significant increase in pediatric orthopedic and soft tissue injuries and cases of hypothermia tasked to the local EDs.11 Storm surges in Hawaii triggered a significant increase in exposure to industrial chemicals and carbon monoxide.11 Fresh water contamination, limited access to clean drinking water and overall breakdown of healthcare infrastructure all contribute to increased gastrointestinal illness outbreaks12,13. The overall breakdown of healthcare infrastructure following future flooding will most acutely be felt in EDs with the sudden influx of patients and rapidly depleting resources. We may even see EDs and hospitals flood and must make contingency plans to anticipate the trajectory of our changing climate.

Heat waves impending impact on EM

Climate prediction models predict an increase in heat waves for almost all major cities in Canada and North America.14 The medical complications of heat waves include prickly heat, heat cramps, heat edema, heat syncope and heat stroke. The elderly are particularly vulnerable to extreme heat in part due to reduced mobility, decreased thirst sensation, reduced ability to sweat and increased susceptibility to dehydration.14 This is also true of other socially-disadvantaged populations. In Vancouver, Canada in 2009, the majority of heat-related mortality was concentrated in the area of the city populated by marginalized and insecurely-housed patients.15 Prior to the widespread proliferation of air conditioning in North America, there was a 300% increase in mortality and a 500% increase in long-term care mortality during heatwaves.14 Importantly, there are also increased rates of domestic violence and assault associated with increased ambient temperatures during a heatwave.16,17 There is also a link between extreme heat and mental illness exacerbations presenting to the ED.18,19 Heatwaves are associated with significant increases in ED visits for acute renal failure, cardiovascular disease, diabetes and electrolytes disturbances.16 Overall, we can expect more visits to EDs for heat related illnesses.

Vector-borne diseases impending impact on EM

As the climate changes it may increase the range for vectors capable of carrying disease, including mosquitos, ticks and bats. By 2085, more than 6 billion people worldwide may be at risk of exposure to Dengue via the increasing range of the aedes mosquito.20 These mosquitos also carry Chikungunya and Zika virus. The Caribbean, Latin America, Asia and the southern United States are predicted to be particularly impacted by the spread of the aedes mosquito, potentially introducing diseases unfamiliar to many emergency practitioners in North America. The geographic range of tarsalis mosquito which carries the West Nile virus  is also slowly marching north related to warming global temperatures.21 The Ixodes scapularis tick (blacklegged tick) is a vector for the spirochete Borrelia burgdorferi, the organisms that causes clinical Lyme disease.22 Related to climate change, with rising temperatures and longer summers in southern Canada and norther United States, the geographic area hospitable to blacklegged ticks has grown, resulting in a significant increase in Lyme disease.22,23,24 Emergency physicians need to understand and anticipate how climate change may drastically alter the vector-borne diseases we see presenting to the ED.

Forest fires impending impact on EM

At the time of writing, multiple areas in Canada are blanketed by forest fire smoke. Long-term trends of rising temperatures and variable rainfall patterns contribute to the increasing severity and frequency of forest fires25,26 The size of particulate produced from forest fires is measured as PM10 or PM2.5. PM10 levels correlate with asthma symptoms, oral steroid prescription, mean daily symptoms counts and mean daily dose of inhaled bronchodilators.27 Symptoms of dyspnea, cough, chest tightness and sputum production all present more frequently to EDs during fires.28 Pediatric wheeze, cough and chest tightness all correlate with PM10 levels driven by forest and bush fires.29 Asthma-related visits to EDs also increase up to 20% during active forest fires.25 A Canadian study in 2003 demonstrated that respiratory consultation in British Columbia peaked 5 weeks after the height of the forest fires, hinting at delayed respiratory complications associated with forest fires.30 Forest fires also resulted in a 5% increase in both cardiovascular and all-cause mortality in Australia.26 Finally, PM2.5 is correlated with increased cardiac presentations to the ED.30 It is easy to see the effects that forest fires are having on Canadians and we can anticipate more visits to EDs driven by forest fires.

Opportunities for action for climate change’s impending impact on Emergency Medicine

The 2019 Lancet declaration on climate change stated that “symptomatic intervention and palliation must also be accompanied by immediate action to address the cause of those symptoms”.31

Below we outline some opportunities for action:

  1. Increased education on climate change and planetary health. We advocate for increased education at all levels of medical education on climate-related pathologies including heat illness, complications of forest fires and changing vector-borne disease.
  2. Increased resource allocation in EDs for climate-related pathologies. This includes respiratory support, mental health resources, rapid diagnostic kits for vector-borne disease etc.
  3. Increased disaster planning for climate-related emergencies. We advocate for increased training of mass casualty and disaster planning for areas prone to climate emergencies such as floods, forest fires and extreme heath events.

The ED is uniquely positioned to declare sentinel events, advocate on behalf of vulnerable populations and lead by example. It is time for the medical education of future emergency physicians to not only emphasize the social, but also the environmental, determinants of health.


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