UBC EnviroMed

The changing climate in British Columbia stands to impact patient health through an increase in zoonotic diseases, air pollution, and an increase in extreme weather events, including heat waves, droughts, wildfires, and flooding.

With many variables at play, it is difficult to predict the full scope of climate change’s impact on human health. To adapt to these changes, healthcare providers can take a proactive approach, and focus on adaptation strategies to the major threats impacting BC patients.  

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1: Zoonotic Diseases

Zoonoses are infectious diseases that are transmissible from vertebrate animals to humans under natural conditions, either directly or via insect vectors. Causal agents include viruses, bacteria, parasites, fungi and prions. Approximately 60% of all known infectious diseases are zoonotic. [2]

Largely, zoonotic infections can be divided into enteric (those that impact the gastrointestinal system), and non-enteric (those that do not).

DIRECT IMPACTS

The changing climate creates environments more suitable for vector and pathogen development in a variety of ways:

• Climate change & rising temperatures increase the development and reproduction of pathogens. This can be partially accounted for by the fact arthropod vectors are largely exothermic, meaning they rely on external temperature to regulate their internal conditions. In addition, the larval development stage generally requires increased humidity and temperature.
• Biting rates of vectors tend to increase with increasing temperature (to an upper limit). [4,5]

INDIRECT IMPACTS

Climate change stands to impact the transmission of VBD by increasing the spread of infectious diseases, with population shifts and changes in land use creating increased opportunities for transmission.

Shifts in the population often result from climate change causing a reduction in suitable living conditions and increased conflict over resources, leading to climate refugees (those forced to relocate due to climate change). As populations shift, there are changes in land use, via both urbanization and agricultural expansion. These factors influence exposure to vectors and thus the transmission of pathogens. [6]

GLOBAL SCALE

Globally, diseases of concern include malaria, dengue, yellow fever, chikungunya and zika. [7] Despite advancements in public health and disease prevention, globally, vector-borne diseases remain an increasing public health burden and stand to be further impacted by climate change. For example, dengue fever has increased in incidence by 30-fold over the last 50 years, and recently outbreaks of dengue fever have been reported in the United States, Madeira, Croatia, China and Japan. [8]

Physicians are also likely to encounter greater numbers of other mosquito-borne diseases including Chikungunya, Dengue, and Zika in travellers. These diseases are not present in Canada but stand to increase their current geographic range due to:

• an increase in exotic pathogens and their vectors outside of Canada
• an increase in travel and global trade,
• increased introduction of pathogens and vectors and increased climate suitability in Canada.

Though these diseases may not expand their range to BC, they will increase their range into areas that Canadian travellers visit, including the Caribbean, Latin America, and Asia. The number of dengue cases reported to WHO increased over 8 fold over the last two decades. [8]

VBD IN CANADA

Although traditionally in Canada, tropical VBDs have not been of concern, increasing temperatures and an overall milder climate may lead to both the introduction of and increased cases of VBD. A review in 2015 identified emerging vector-borne zoonotic diseases of public health importance in Canada, which identified tick-borne diseases including Lyme disease, WNV and other mosquito-borne diseases as a high priority. [9]

Canada-wide differences in Lyme Disease

• In contrast, BC has seen lower and more stable numbers of Lyme disease cases in comparison to central and eastern Canada. Despite expected greater tick numbers in BC the number of people exposed to Lyme disease is not expected to greatly increase.
• The reasons for this are multifactorial, in part due to differences in tick species, with the Western Blacklegged tick found in B.C, (I. Pacificus) carrying a relatively low risk of Lyme disease in comparison to the eastern black-legged tick (I. scapularis), found in central and eastern Canada. [6] Other factors include differences in tick diet and regional differences in vegetation and climate. [12]

ADAPTATION STRATEGIES

1. Awareness
   • Ticks can be found year-round, most likely to bite in the spring (March to June) [12]
   • Populations at higher risk for tick-borne disease include:
     • Those involved in outdoor activities (hunting, fishing, hiking, camping, gardening, forestry, farming)
     • Those who live in known endemic areas
     • Those ages 5-9 or older (age 55+) [13]
   • Encourage patients to identify the risk of Lyme Disease in their area
2. One-Health Approach
   • Currently, the “One Health” approach is being used, in which multiple sectors collaborate to create solutions. For example, to manage infectious disease, communication between leaders in agriculture, global trade and healthcare will allow for a coordinated approach. Focus will be placed on the interaction between humans, animals, and the evolving environment. [5] 
   • For example, read more about the E-tick app, a way to record tick encounters here.
3. City-Level Change
   • City design centred around increasing green space is key in reducing urban heat island effects and decreasing areas prone to stagnant water buildup. [5]
   • Have an idea for a green space project in Vancouver? Apply for a grant here.
4. Reporting
   • Physicians play an important role in surveillance by reporting cases to public health. A study by Dr. Bonnie Henry found that only 62% of B.C. physicians were aware that Lyme disease was a reportable condition in BC, highlighting the importance of physician education on procedure to ensure disease incidence is reported. [14]Familiarize yourself with the current risk of vector borne diseases in your area, and which diseases are reportable.Provide guidance to patients about risk and prevention strategies. [15]

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2: Air Pollution

Air pollution is a complex mixture of particles. Sources of air pollution include both solid and liquid particles suspended in the air (known as Particulate Matter), various gases (such as ozone, nitrogen dioxide, and carbon monoxide), and biological molecules. [1] 

Although largely in Canada we are able to enjoy clean air, some significant examples of air pollutant sources include vehicle emissions, industrial emissions (for example, sawmills, pulp and paper mills), in addition to smoke produced from indoor and outdoor burning. [2] 

Two components of air pollution that pose a significant risk to health include Particulate Matter and Ground Level Ozone. [3]

“Air pollution is a threat to health in all countries, but it hits people in low- and middle-income countries the hardest.”

—WHO Director-General, Dr Tedros Adhanom Ghebreyesus.

GLOBAL SCALE

Air pollution is considered to be the largest environmental risk to health on a global scale, [10] far exceeding others, such as lack of clean water and sanitation. Disparities are highlighted, with lower-income countries facing higher PM2.5 levels. It was responsible for 8.7% of global deaths in 2017, primarily due to its contribution to respiratory and cardiovascular mortality and mortality. [11]

In 2020, 23% of COPD deaths, 12% of ischemic heart disease deaths, and 12% of stroke deaths were attributable to daily exposure to household air pollution. This was also responsible for 44% of pneumonia deaths in children less than 5 years old, [12]

IN CANADA

In comparison to the rest of the world, Canada has one of the lowest fine particle air pollution exposure levels, but its effects are not insignificant.

Air pollution is associated with approximately 15,300 premature Canadian deaths per year, with 1,900 in British Columbia. [13,14]

The cost of health impacts attributable to air pollution is $120 billion, approximately 6% of Canada’s GDP in 2016. [15]

In one of the largest analyses to date, ambient air pollution exposure was associated with decreased lung function and increased COPD prevalence. This association was stronger in those with lower incomes. This was further confirmed by a 2019 study, finding that ambient air pollution in Canada was associated with lower lung function, with 27% of participants living in Vancouver, BC. [16,17].

ADDRESSING MODIFIABLE RISK FACTORS & PREVENTING ADVERSE HEALTH OUTCOMES

Educate patients about the health effects of air pollution.

There is confusion surrounding the connection between climate change, air quality, and patient health. [26]

Understanding on the effects of climate on air pollutants and aeroallergens, their effects on respiratory and cardiovascular health, and how to reduce these exposures will equip you to educate patients and reduce vulnerability. [19]

For example, patient education about lengthening allergy seasons, and areas high risk for exacerbations allows for patients to take initiative for their health. Asthma education programs have been shown to reduce asthma related emergency department visits and hospitalizations. [27]

Discuss Adaptation Strategies with Patients

Consider proactively starting discussions with those most vulnerable to the effects of air pollution,  such as children, the elderly, and people with chronic respiratory and cardiovascular diseases. [28] 

When asking about patient lifestyle, focus on modifiable risk factors that can help minimize air pollutant exposure. Some examples include:  

• Their activities (time of day, location, exertion level) 
• Location of residence 
• Safety of work environment, and any exposures to air pollutants 
• Possible integration of air cleaners, masks or medications [18]

Some common adaptation strategies include: 

• Reduce/ stop smoking 
• Limit fireplace and woodstove use 
• Monitor outdoor air quality (via the Air Quality Health Index from Health Canada, or the Plume app)  
• Choose less strenuous activities during times of poor air quality  
• Reduce time spent near high traffic areas [29]

Advocate for air quality improvement.

Having this foundation of knowledge can allow you to advocate for expansion of current research on changing pollutant levels, allergic sensitization, and overall health trends shaped by climate change.[19]

Advocacy work that increases awareness of the impacts of air pollution can lead to more funding for systems to combat these outcomes. One example is improved warning systems for physicians and the public to forecast and be aware of times of reduced air quality or increased pollen levels, so preventative measures may be taken. [30]

Share resources with patients

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3: Extreme Weather – Heat

Heat and Health

The continual warming of our climate has been well documented, with relevance in Western Canada, where up to a 3-degree Celsius increase in temperature above pre-industrial levels has been observed. [1,2] The continual warming of our climate has been well documented, and Canadian temperatures have increased at approximately twice that of the global rate, and 9 of the 10 warmest years have occurred during the last 25 years. [3]

In western Canada, June 2021 was witness to a historic heat wave record, where a temperature of 49.6 degrees Celsius was observed in Lytton, British Columbia. The extreme heat was responsible for 619 deaths in British Columbia. [4]

Our warming climate will result in increased intensity, frequency, and severity of heat waves and result in negative health impacts such as heat stress, heat stroke, and exacerbation of conditions such as cardiovascular and renal disease. [5,6,7]

Pathophysiology of Heat Response.

Normally, in response to increased core and surface temperature, your body attempts to dissipate this heat through vasodilation, increased cardiac output, and diaphoresis. [8,9]

In cases of extreme heat and heatwaves, these compensatory mechanisms can fail, causing a cascade of events leading to a systemic inflammatory response, and resulting heat stroke. Heatstroke is the most severe form of heat illness and is a health emergency, seen clinically as a core temperature of 39-40 degrees Celsius, central nervous system dysfunction, and multi-organ failure. [10]

A comprehensive overview of heatstroke can be found here.

Vulnerable Populations

Understanding which populations are more susceptible to the effects of heat is imperative in preventing negative health outcomes.

This is a non-exhaustive list, but some other examples include: 

• The elderly [11,12]
• Urban populations [13,14]
• Those with chronic illnesses [13,15,16]
• Homeless populations [17]
• Women- to learn more about how heat waves disproportionally impact women, click here.

Stay alert and keep your patients informed.

The treatment for heat stroke is rapid cooling, with its prevention being far superior than any cure. [18] As a future physician you have the opportunity to identify these vulnerable populations, and initiate conversation about the increasing risk of heat waves during the summer months. Some heat stroke  prevention strategies include: 

• Monitoring those at risk (such as elderly patients living alone) by encouraging community  check-ins with these individuals during heat waves. 
• Teach vulnerable patients to be aware of heat wave warnings, and to ensure access to water, and cooling facilities.
• Prevent heat related illness by avoiding outdoor activity between 10am and 4pm, taking a cool bath or shower, and ensuring hydration. [19] 
• Encourage active living which among its many other benefits, is also shown to improve heat tolerance. [20]

Invest in long term outcomes.

While education plays a key role in patient safety, ultimately adaptations will need to be made to accommodate our rapidly changing climate. Infrastructure changes, such as decreasing urban heat island effects through tree planting, increased water fountain installations, and use of appropriate  building materials to reduce heat trapping in buildings and pavement are all tactics currently in Surrey’s Climate Adaptation Strategy. [21] 

As physicians we can also play a role by getting involved in policy to advocate for our patient’s  health, and for further climate adaptive infrastructure developments. For example, family physicians can get involved with school boards, recreation programs, and sports medicine advisory committees to discuss and advocate for heat safety improvements. [22]

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Review of Heat-Related Deaths in BC in June 2021: Highlighting opportunities for patient education during physician contact.

In June 2021, 619 heat-related deaths occurred in British Columbia. 67% of these patients were age 70 or older, and more than 80% had 3 or more chronic diseases.

Upon review, it was found that over 60% of these individuals had seen a medical professional the month prior to their passing, with 62% having 12 or more visits with health professionals within 12 months before their death.

This highlights the opportunity for physician identification of patients at high risk of being impacted by heat waves and providing education.

Planned action after this event:

• Implementation of a coordinated provincial heat alert and response system
• Identifying populations at greatest risk, identified by Home and Community Care Services and developing messaging for these populations
• Long-term risk mitigation by increasing public service messaging on heat preparedness, and increased cooling requirements in future building codes. [4]

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Extreme Cold

During the winter months, temporary winter response shelters, and extreme weather response (EWR) shelters are available throughout British Columbia. This information is currently shared with service providers, outreach teams, and TransLink. Future physicians can support patient health by being aware of local extreme cold weather alerts, discussing this with patients experiencing homelessness, or without adequate heating and providing resources.

Resources for Patient Information

Emergency Shelters – Locate shelters in British Columbia

Emergency Preparedness– How to prepare and stay safe in the extreme cold

Government of Canada – Steps for cold weather safety

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