March 29, 2021

By Michael Twigg


The health benefits of urban nature are well established – more greenspace means a lower risk of cardiovascular diseases and respiratory illnesses, and integrated urban ecosystems improve air quality and reduce the urban heat island effect. The Canadian Association of Physicians for the Environment (CAPE) estimates that enhancing urban nature to achieve Canada’s net zero targets would remove enough CO2 to avoid up to 11,000 deaths caused by air pollution every year1. When considering all causes of poor environmental health in Canada and their impact on the incidence of heart disease, stroke, diabetes, and respiratory illnesses, the protective effect of more greenspace in Canadian cities increases to 34,000 fewer annual deaths2. A conservative estimate of the health cost savings from greening Canadian cities would result in cost savings of $100 billion by 2050.


The health and economic impact of COVID-19

The contributing role of nature to reduce the burden of disease is even more important in light of the health and economic impact of the COVID-19 pandemic. More than 22,000 lives have been lost in Canada over the past year due to COVID-19, with more than $320 billion dollars spent fighting the spread of the virus in 20203,4. Emerging evidence points to the co-morbidity of several pre-existing, non-communicable diseases as the primary factor increasing the severity of symptoms and causing COVID-involved deaths. In fact, during the first wave, 90% of all reported deaths from COVID-19 were shown to have at least one pre-existing health condition; that number increases to 100% when examining those affected under the age of 45. Most of these pre-existing conditions included those linked to poor environmental health – Alzheimer’s or dementia (37%), heart disease (15%), hypertension (13%), diabetes (12%), respiratory failure (12%) and respiratory diseases (10%)5.


How can nature-based solutions prevent future pandemics?

Beyond reducing severity of diseases that exacerbate COVID-19, emerging evidence suggests that investing in nature-based solutions (NBS) to enhance urban greenspaces is a cost-effective way to reduce the risk of recurrence. At the very least, NBS can help build the health resilience of Canadians to withstand similar challenges in the future. Below are three ways that NBS can help build the health resilience of Canadian communities. 


1) Increasing greenspace cover can reduce favorable environmental conditions for the propagation of pathogens

Investing in NBS to improve urban nature can reduce the overall epidemiological burden of disease in urban environments by reducing transmission vectors of communicable diseases from habitat loss and human encroachment6. Nature is known to provide a physical buffer to reduce the possibility of zoonotic transmission whereby pathogens pass from non-humans to humans. When West Nile Virus first emerged in North America in the early 2000s, transmission was shown to be influenced by the urban natural environment - virtually all cases of the virus occurred in disturbed wetland areas and in neighborhoods with limited greenspace7. Furthermore, human-to-human viral transmission rates are shown to be directly impacted by urban temperatures, humidity, and air pollution through their direct impact on the dilution rate of viral aerosols8. In the case of COVID-19 a strong correlation has emerged between the life span of infectious viral aerosols and ambient levels of PM2.59.

These factors suggest that efforts to improve and conserve urban nature may be able to create environmental conditions that reduce the spread of communicable diseases and limit the increasing number of pathogens emerging in high density urban areas.


2) Greenspaces can be an important physical distancing buffer against the spread of communicable diseases

In the wake of COVID-19, compact, high density urban designs were insufficient to meet physical distancing guidelines10. Many cities resorted to temporary measures to overcome existing design challenges, such as closing parks and public spaces, erecting temporary barriers to expand pedestrian areas, and creating outdoor waiting and seating areas. Even though the preference for compact urban designs is unlikely to change due to the advantages of centralized health and social service delivery, the need to address physical distancing in these areas represents an opportunity to better integrate urban vegetation as natural spatial barriers11. Separating major active transportation routes using street trees, providing more open spaces for socializing and physical activity, and conserving more natural vegetation as physical buffers can help limit the transmission of communicable diseases, while also providing other substantial co-benefits to improve community health - e.g., encouraging outdoor recreation and building climate resilience.


3) Increasing access to urban nature can help prevent a mental health echo pandemic

Millions of Canadians are facing additional stress and anxiety from lost employment, social upheaval from restriction in schools and workplaces, and living in fear of infection. The additional mental health impacts of COVID-19 are being equated to those experienced from large-scale traumatic events, such as natural or environmental disasters. The negative impact of social isolation has led to several Canadian mental health organizations sounding the alarm on an impending echo pandemic driven by increasingly poor mental health12. Existing services are strained to provide the necessary support for those already suffering from poor mental health, increasing the vulnerability of these populations. Left untreated, a recent study suggests that the mental health of Canadians will continue to degrade over the next year, reducing overall well-being across many communities.

Exposure to nature provides additional support to improve mental health. Spending more time in nature offers vital relaxation and restoration that many people have been craving while being isolated from their family, friends, and communities. Walking outdoors, gardening or even just looking outside have all been shown to significantly reduce stress and anxiety associated with social isolation, which makes having access to nature in urban areas a vital source of calm and wellbeing for many Canadians.  Feelings elicited by spending time in nature (forest bathing) are comparable to those of being on vacation, away from everyday struggles13. Without diminishing the severity of mental health issues, reminding people to get outside can help reduce the additional stress and anxiety caused by the COVID-19 pandemic and encourage healthy habits to improve mental health resilience in the face of future pandemics.


Building back better from COVID-19 using NBS

With investment in infrastructure and natural infrastructure anticipated as part of economic recovery efforts, Canadian cities have the unparalleled opportunity to redesign the urban environment. Using NBS can improve well-being, reduce the transmission of pathogens, and build buffers against disease. To help prevent future pandemics and build the health resilience of Canadian communities, nature must be part of the equation.  


To find out more about how nature can help us build back better in response to COVID-19, Smart Prosperity will be hosting a webinar in Spring 2021 on the health benefits of using NBS that will coincide with a report released on the same topic. Subscribe to our newsletter to stay informed about all our upcoming releases and events.


1 Edger, R., Howard, C., Lem, M., Zigby, J., Pétrin-Desrosiers, C., Doyle H.M., Kitching, G.T., Luo, O.D., Cohen, A.,Wu, K., Kirsh Carson, J.J., Létourneau S.G., & Kuhl, J. 2020. “Healthy Recovery Plan: For a Safe and Sustainable Future.” Canadian Association of Physicians for the Environment.

2 Crouse, Dan L, Lauren Pinault, Adele Balram, Perry Hystad, Paul A Peters, Hong Chen, Aaron van Donkelaar, et al. 2017. “Urban Greenness and Mortality in Canada’s Largest Cities: A National Cohort Study.” The Lancet Planetary Health 1 (7): e289–97.

3 Public Health Agency of Canada. 2021. Coronavirus disease 2019 (COVID-19): Epidemiology update. Government of Canada. Accessed March 26, 2021.

4 Department of Finance. 2020. Supporting Canadians and Fighting COVID-19: Fall Economic Statement 2020. Government of Canada. Accessed March 24, 2021.

5 O’Brien, Kathy, Marylène St-Jean, Patricia Wood, Stephanie Willbond, Owen Phillips, Duncan Currie and Martin Turcotte. 2020. COVID-19 Death Comorbidities in Canada. Government of Canada. Accessed March 25, 2021. 

6 Dobson, Andrew P., Stuart L. Pimm, Lee Hannah, Les Kaufman, Jorge A. Ahumada, Amy W. Ando, Aaron Bernstein, et al. 2020. Ecology and Economics for Pandemic Prevention. Science 369 (6502): 379–81.

7 Kauffman, E. 2016. WNV: Emerging Threat to the Americas and Opportunities for Control. CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources 11 (011).

8 Zhang, Renyi, Yixin Li, Annie L. Zhang, Yuan Wang, and Mario J. Molina. 2020. Identifying Airborne Transmission as the Dominant Route for the Spread of COVID-19. Proceedings of the National Academy of Sciences 117 (26): 14857–63.

9 Ibid

10 Sharifi, Ayyoob, and Amir Reza Khavarian-Garmsir. 2020. The COVID-19 Pandemic: Impacts on Cities and Major Lessons for Urban Planning, Design, and Management. Science of The Total Environment 749 (December): 142391.

11 Ibid

12 CMHA. 2020. Policy Brief: COVID-19 AND MENTAL HEALTH: HEADING OFF AN ECHO PANDEMIC. Canadian Mental Health Association. Accessed March 24, 2021.

13 Howarth, Michelle, Alistair Griffiths, Anna da Silva, and Richard Green. 2020. Social Prescribing: A ‘natural’ Community-Based Solution. British Journal of Community Nursing 25 (6): 294–98.