Sheltered from the heat? How tents and shade covers may unintentionally increase air temperature exposures to unsheltered communities

Overexposed and Understudied: Environmental Risks Among Older Adults Experiencing Homelessness in Phoenix, Arizona

Individuals experiencing homelessness are highly vulnerable to urban environmental hazards, such as heat and air pollution, due to a lack of stable housing and limited access to indoor or cooled spaces. These risks are heightened for older adults and individuals with preexisting health conditions. With intensifying summer heat in the American Southwest and the persistence of urban homelessness, this study explores how older adults experiencing homelessness in Phoenix, Arizona perceive and interact with heat and air pollution as well as the adequacy of available coping resources and information. A survey was co-produced with community members with lived experience. A sub-group of community members assisted in proctoring the surveys among adults 55 and older at a downtown service agency. Survey results informed the location of data collection using MaRTy-a mobile biometeorological cart-and remotely sensed fine particulate matter (PM2.5). Findings reveal that heat and air pollution significantly influence travel decisions and contribute to health issues for many respondents. Midday and evening thermal radiation levels regularly exceeded safe thresholds, while PM2.5 concentrations often surpassed annual air quality guidelines, though they posed less acute health risks. Most participants reported awareness of health risks and employed strategies to reduce exposure. However, many expressed that city-level, public resources are insufficient to prevent heat- and air pollution-related health issues. Findings underscore the need for targeted interventions-such as better access to transportation and essential healthcare and extended hours of operation for service providers-to enhance resource accessibility and mitigate environmental health risks for vulnerable populations.

Impact of tent shade on heat exposures and simulated heat strain for people experiencing homelessness

Concurrent increases in homelessness and heat intensity, duration, and frequency translate to an urban heat risk trap for the unsheltered population. Homelessness is both a driver and consequence of poor health, co-creating distinct geographies with various risk factors that exacerbate heat vulnerability. We tested the efficacy of different tent shadings over identical tents often observed in the Phoenix area (white bedsheet, mylar, tarp, and aluminum foil) and compared them to a control tent (uncovered) and ambient conditions. We monitored all meteorological variables at all six locations, notably Mean Radiant Temperature (MRT). The in-tent microclimate variability was applied to complete statistical and physiological modeling including substance use on heat strain. Findings indicate that tent shadings resulted in significantly lower in-tent MRT during the day (p < 0.05), but exacerbated in-tent thermal risk during the night compared to the control tent and ambient conditions. Furthermore, we found evidence that the temperature metric matters, and using only either MRT or air temperature (Tair) to assess "heat" could lead to inconsistent conclusions about in-tent microclimate. Interactions between shade types and time significantly amplified in-tent thermal risk. Physiological modeling indicates a higher risk of heat strain (core temperature beyond 40˚C) for people using substances. Decision makers should promote testing different heat intervening strategies toward realizing effective means of protecting human life and preventing heat illnesses. This study illuminates the need for an interdisciplinary approach to studying tents as shelters that considers the total heat load with heat strain modeling.

"Death Is a Possibility for Those without Shelter": A Thematic Analysis of News Coverage on Homelessness and the 2021 Heat Dome in Canada

Among the most vulnerable to the health-harming effects of heat are people experiencing homelessness. However, during the 2021 Heat Dome, the deadliest extreme heat event (EHE) recorded in Canada to date, people experiencing homelessness represented the smallest proportion of decedents (n = 3, 0.5%)-despite the impacted region (British Columbia) having some of the highest rates of homelessness in the country. Thus, we sought to explore the 2021 Heat Dome as a media-based case study to identify potential actions or targeted strategies that were initiated by community support agencies, individuals and groups, and communicated in the news during this EHE that may have aided in the protection of this group or helped minimize the mortality impacts. Using media articles collated for a more extensive investigation into the effects of the 2021 Heat Dome (n = 2909), we identified a subset which included content on people experiencing homelessness in Canada (n = 274, 9%). These articles were thematically analysed using NVivo. Three main themes were identified: (i) public warnings issued during the 2021 Heat Dome directly addressed people experiencing homelessness, (ii) community support services explicitly targeting this population were activated during the heat event, and (iii) challenges and barriers faced by people experiencing homelessness during extreme heat were communicated. These findings suggest that mass-media messaging and dedicated on-the-ground initiatives led by various organizations explicitly initiated to support individuals experiencing homelessness during the 2021 Heat Dome may have assisted in limiting the harmful impacts of the heat on this community.

Concurrent Heat and Air Pollution Exposures among People Experiencing Homelessness

BACKGROUND

Extreme heat and air pollution are important human health concerns; exposure can affect mental and physical well-being, particularly during periods of co-occurrence. Yet, the impacts on people are largely determined by underlying health conditions, coupled with the length and intensity of exposure. Preexisting adverse health conditions and prolonged exposure times are more common for people experiencing homelessness, particularly those with intersectional identity characteristics (e.g., disease, ability, age, etc.). Partially due to methodological limitations, such as data scarcity, there is a lack of research at the intersection of this at-risk population within the climate-health domain.

OBJECTIVES

We have three distinct objectives throughout this article: a) to advance critical discussions around the state of concurrent high heat and air pollution exposure research as it relates to people experiencing homelessness; b) to assert the importance of heat and air pollution exposure research among a highly vulnerable, too-often homogenized population-people experiencing homelessness; and c) to underline challenges in this area of study while presenting potential ways to address such shortcomings.

DISCUSSION

The health insights from concurrent air pollution and heat exposure studies are consequential when studying unhoused communities who are already overexposed to harmful environmental conditions. Without holistic data sets and more advanced methods to study concurrent exposures, appropriate and targeted prevention and intervention strategies cannot be developed to protect this at-risk population. We highlight that a) concurrent high heat and air pollution exposure research among people experiencing homelessness is significantly underdeveloped considering the pressing human health implications; b) the severity of physiological responses elicited by high heat and air pollution are predicated on exposure intensity and time, and thus people without means of seeking climate-controlled shelter are most at risk; and c) collaboration among transdisciplinary teams is needed to resolve data resolution issues and enable targeted prevention and intervention strategies. https://doi.org/10.1289/EHP13402.