When the Commute Becomes a Risk: The Invisible Heat Burden of Public Transit

Nguyen Thi Nguyet Nuong

East Asian University of Technology, Hanoi, Vietnam

Contact: nuongntnt@eaut.edu.vn

31-05-2026

© Margo Evardson

On June 2021, a record-breaking heatwave swept across the Pacific Northwest of North America. Temperatures soared to unprecedented levels, contributing to more than 600 heat-related deaths in the Canadian province of British Columbia alone (White et al., 2023). Most victims were older adults, people with chronic illnesses, and individuals from lower-income communities—groups already vulnerable to environmental stress (Egilson et al., 2022).

When discussing heat-related health risks, attention often focuses on homes, workplaces, or neighbourhoods. Yet an important source of exposure frequently remains overlooked: the daily journey between them.

Public transit users face unique challenges during extreme heat events. Unlike private vehicle users, transit riders spend time walking to transit stops, waiting outdoors, and transferring between routes. These seemingly routine activities can expose individuals to dangerous temperatures, especially in cities affected by the urban heat island effect, where asphalt, concrete, and buildings absorb and retain heat (Rizwan et al., 2008; Lanza et al., 2025).

A recent study examined this overlooked problem using Vancouver, Canada, during the 2021 heatwave as a case study. By combining high-resolution urban climate models with simulations of transit journeys, researchers assessed how much heat exposure transit users experienced and how much protection—such as shade from trees or transit shelters—was available throughout their trips (Shaver et al., 2026).

The findings revealed a troubling pattern. Neighbourhoods with larger proportions of marginalized populations were more likely to experience the highest levels of heat exposure while simultaneously having the lowest levels of heat-mitigating infrastructure. In other words, those most vulnerable to heat were often the least protected from it.

This finding illustrates a common challenge in addressing complex socio-ecological problems. In urban heat adaptation, policymakers often focus on visible indicators such as city-wide temperature averages, public cooling centres, or neighbourhood-level greening programs. These interventions are valuable. However, they can inadvertently obscure a critical layer of the system: the transit journey itself (Nguyen, 2026).

A transit trip may appear as a short and insignificant component of daily life. Yet, it consists of numerous interactions between people, infrastructure, and environmental conditions. A ten-minute wait at an unshaded bus stop during extreme heat can become a significant health risk, particularly for older adults or individuals with pre-existing medical conditions. When thousands of such interactions occur daily across a city, their cumulative effects become substantial.

The study demonstrates that climate vulnerability is not merely determined by where people live but also by how they move through urban environments. Heat exposure emerges from interconnected systems of transportation, infrastructure, urban design, and social inequality (Vuong, 2025; Khuc & Nguyen, 2026).

As cities prepare for a warmer future, climate resilience may require looking beyond what is most visible. Sometimes the greatest risks are hidden in ordinary routines—such as waiting for a bus on a hot afternoon. By revealing these overlooked interactions, transit planning can become not only more climate-resilient but also more equitable.

References

Egilson, M, et al. (2022). Extreme heat and human mortality: A review of heat-related deaths in B.C. in summer 2021. Government of British Columbia. https://www2.gov.bc.ca/assets/gov/birth-adoption-death-marriage-and-divorce/deaths/coroners-service/death-review-panel/extreme_heat_death_review_panel_report.pdf

Khuc, V. Q., & Nguyen, M. H. (2026). Cultural Additivity Theory. Available at SSRN 6767760. https://ssrn.com/abstract=6767760 

Lanza, K., et al. (2025). Heat stress mitigation by trees and shelters at bus stops. Transportation Research Part D: Transport and Environment, 140, 104653. https://doi.org/10.1016/j.trd.2025.104653

Nguyen, M.-H. (2026). Ayn Rand and Kingfisher on zero-carbon bombs and a sustainable future. Visions for Sustainability, 25(13474), 1-13. http://dx.doi.org/10.13135/2384-8677/13474  

Rizwan, A. M., Dennis, L. Y. C., Liu, C. (2008). A review on the generation, determination and mitigation of Urban Heat Island. Journal of Environmental Sciences, 20(1), 120-128. https://doi.org/10.1016/S1001-0742(08)60019-4

Shaver, H., et al. (2026). Measuring transit riders’ heat exposure and mitigation during the 2021 Vancouver heatwave. Transportation Research Part D: Transport and Environment, 157, 105398. https://doi.org/10.1016/j.trd.2026.105398

Vuong, Q. H. (2025). Wild Wise Weird. AISDL. https://books.google.com/books?id=C5dDEQAAQBAJ

White, R. H., et al. (2023). The unprecedented Pacific Northwest heatwave of June 2021. Nature Communications, 14, 727. https://doi.org/10.1038/s41467-023-36289-3