Global Climate Implications for Homelessness: A Scoping Review

Novel Method for Measuring Ambient Heat Exposure-Acute Healthcare Utilization Associations Within a Safety Net: A Retrospective, Longitudinal Study

BACKGROUND

Extreme and inequitable heat exposures cause weather-related deaths. Associations between maximum daily temperature and individual-level healthcare utilization have been inadequately characterized.

OBJECTIVE

To evaluate and compare demographic and clinical associations for an individual's healthcare utilization between high- and low-temperature periods.

DESIGN

Retrospective, 5-year longitudinal study of acute care utilization comparing high-temperature periods (HHP) and low-temperature periods (LHP) defined by local maximum daily temperature. Using duration of observation, cases served as their own controls. Temperature-dependent utilization was reported as unadjusted incident rate ratio (IRR) using Poisson regression and log-transformed variable coefficients. IRRs were adjusted (aIRR) for demographic characteristics, heat-sensitive conditions/diagnoses, and neighborhood heat vulnerability score; false discovery rate p-values were adjusted for multiple comparisons.

SUBJECTS

Patients aged ≥ 4 years visiting Denver Health between 4/10/2016 and 12/31/2020, with ≥ 2 visits over ≥ 365 days.

MAIN MEASURES

Comparison of an individual's acute care visit rates in HHP versus LHP, stratified by demographic characteristics and heat-sensitive clinical conditions.

KEY RESULTS

While acute care utilization occurred at similar or higher rates during LHP compared with HHP, certain groups (i.e., Native Americans and those with congestive heart failure, liver failure, and/or alcohol use) had higher rates of utilization during HHP. Significant associations existed for acute care utilization by age, sex, racial and ethnic groupings, clinical characteristics, and neighborhood heat vulnerability. Adjusting for demographic and environmental covariates, individuals with any heat-sensitive clinical condition had higher HHP vs LHP utilization compared to those without (aIRR = 1.93).

CONCLUSIONS

Significant heat-related utilization occurred among individuals with heat-sensitive clinical conditions compared with those without. Demographic characteristics (e.g., older) and specific clinical conditions (e.g., liver failure) demonstrated higher utilization. In real-time, chronic disease management programs could proactively identify at-risk individuals for interventions which reduce heat-related morbidity and healthcare utilization.

Heat-Related Health Risks for People Experiencing Homelessness: A Rapid Review

Extreme heat poses a significant public health threat for people experiencing homelessness (PEH), who face heightened risks due to prolonged outdoor exposure and limited access to resources. This rapid review synthesizes research from the past five years on the health impacts of extreme heat for PEH in high-income countries. A total of 11 studies were identified through a systematic search of multiple databases, focusing on publications from 2019 to 2024. The review highlights key vulnerability factors, including demographic characteristics, pre-existing health conditions, and geographic disparities, that increase heat-related health risks for PEH. Physical health impacts, such as heat-related morbidity and mortality, are common, alongside mental health and substance use disorders exacerbated by heat exposure. The review also highlights a significant increase in emergency department visits among PEH during heat events, emphasizing the additional burden on healthcare systems. Barriers, including limited physical and social access to cooling centers, water insecurity, and stigma, further compound these challenges. Addressing the unique vulnerabilities of PEH is crucial to reducing their risks during extreme heat events. Improving housing access and stability is essential as a long-term strategy to decrease homelessness and reduce heat stress in this vulnerable population. The review also underscores the need for inclusive interventions such as accessible cooling centers with targeted programming, regular access to water, and tailored healthcare services to meet the needs of PEH. Future research should focus on long-term studies to assess potential cumulative heat exposure effects and evaluate the effectiveness of interventions aimed at mitigating extreme heat impacts on PEH, while applying an intersectionality lens to explore how factors like race, gender, and age shape vulnerabilities and potential intervention strategies.

Neoliberalism, Climate Change, and Displaced and Homeless Populations: Exploring Interactions Through Case Studies

There is a growing attention to neoliberal policies and practices as they relate to climate change and housing within academic literature. However, the combined effects of neoliberal political and economic decisions on the interaction between climate change and displaced and homeless populations have not been substantially explored. In this paper, we identify and focus on three key re-emerging themes prevalent within neoliberal discourses: economic considerations, individualization, and short-termism. To examine the intersecting influence of climate change and these themes on vulnerable populations, the following case studies are discussed: displaced populations in the Middle East and North Africa (MENA) region, refugees in Kenya, and tiny homes programs in the U.S. and Canada. The diversified contexts and levels of analysis allow for more nuanced understanding of the variety of ways in which neoliberal influences and climate-induced events impact the most vulnerable populations. We argue for the need to change the framing of these issues, which are often presented in neoliberal terms and are driven by neoliberal logic. We then present potential avenues for resolving the identified issues, such as through systemic changes, development of long-term solutions, and focusing on community-based adaptation (CBA) programs.

Effects of fine particulate matter from wildfire and non-wildfire sources on emergency-department visits in people who were housed and unhoused in San Diego County (CA, USA) during 2012-20: a time-stratified case-crossover study

BACKGROUND

Being unhoused can increase vulnerability to adverse health effects due to air pollution. We aimed to quantify changes in emergency-department visits during and after exposure to wildfire-specific and non-wildfire particulate matter 2·5 μm or less in diameter (PM2·5) in San Diego County (CA, USA) in people who were both unhoused and housed.

METHODS

For this time-stratified case-crossover study, we used data on exposure to wildfire-specific PM2·5 in California and individual-level data for people admitted to the emergency departments of two hospitals (UC San Diego Health emergency departments at La Jolla and Hillcrest, San Diego) in San Diego County between July 1, 2012, and Dec 31, 2020. People with a postcode outside of San Diego County were excluded. Demographic information was age group, race or ethnicity, and transport to the emergency department. Wildfire-specific PM2·5 concentration at the postcode level was previously estimated using an ensemble model that combined multiple machine-learning algorithms and explanatory variables obtained via data on 24-h mean PM2·5 concentrations from the US Environmental Protection Agency Air Quality System. Conditional logistic regression models were applied, adjusting for specific humidity, wind velocity, and maximum temperature extracted from the US Gridded Surface Meteorological Dataset. Housing status was established by registration staff or triage nurses on arrival at the emergency department. For people who were unhoused, exposure was defined based on the weighted mean PM2·5 concentration at the city level proportional to the number of people who were unhoused in each specific city across urban centres in San Diego County. For people who were housed, we used residence postcode to measure exposure. We assessed the association between PM2·5 from wildfire and non-wildfire sources and emergency-department visits in people who were housed and unhoused.

FINDINGS

There were 587 562 emergency-department visits at the two hospitals, 76 407 (13·0%) of which were by people who were unhoused. People who were housed had a higher exposure to overall PM2·5 (24-h mean over the study period of 9·904 mg/m3, SD 3·445) and non-wildfire PM2·5 (9·663, 2·977) than people who were unhoused (9·863, 3·221; 9·557, 2·599). However, people who were unhoused had a higher exposure to wildfire-specific PM2·5 (0·305, 1·797) than people who were housed (0·240, 1·690). Overall PM2·5 exposure was associated with increased odds of emergency-department visits for both people who were housed (odds ratio 1·003, 95% CI 1·001-1·004 per 1 μg/m3 PM2·5 for 0-3 days after exposure) and people who were unhoused (1·004, 1·000-1·008 for 0-3 days after exposure). We found that non-wildfire PM2·5 was associated with emergency-department visits among people who were housed (1·003, 1·002-1·005 for 0-3 days after exposure) and wildfire-specific PM2·5 was associated with emergency-department visits in people who were unhoused (1·006, 1·001-1·011 for 0-3 days after exposure).

INTERPRETATION

People who were unhoused in San Diego County were more likely to visit emergency departments after exposure to increased wildfire-specific PM2·5. As the intensity and frequency of wildfires increase, understanding risk factors for vulnerable populations, such as people who are unhoused, is crucial to develop effective adaptation strategies.

FUNDING

US National Institutes of Health, National Institute on Aging.

Impact of Natural Disasters on Mental Health: Evidence and Implications

Natural disasters are large-scale catastrophic events, and they are increasing in frequency and severity. Converging evidence indicates that the mental health consequences of disasters are extensive and are often associated with trauma and the disruption of personal and socioeconomic factors in people's lives. Although most individuals experiencing disaster-related traumatic events do not develop mental illnesses, some experience adverse psychological effects of disasters. These mental health effects begin immediately following a disaster and may persist for extended periods. In this article, we summarize the literature findings to provide a narrative review that focuses on the mental health consequences of natural disasters. An overview of the disaster mental health research field is provided, and the findings are ordered into theoretical frameworks. Then, the development and course of psychopathology regarding disaster aftermath are described in a methodological context. Next, understanding a disaster as an event of transition is highlighted, and the impact of this disaster-specific transition is discussed. Lastly, a potential relationship between the transitional impact of a disaster and mental health consequences is speculated on, and the implications are discussed. The impact of disasters on mental health can be direct or indirect, short-term or long-term, and to some extent depends on the recovery process of the affected community. Also, we propose the possible merits of using the Transitional Impact Scale in the context of disaster mental health research by assessing the features of disaster-related transition and its effects on mental health. We conclude by suggesting a direction for future research in terms of measuring the disaster mental health effects in community settings (affected vs. non-affected) and also considering cross-cultural and cross-regional differences. In recent decades, a large amount of knowledge has been gathered from disaster mental health research, but, still, more research is needed to resolve some irregular findings through refining the methodological variations.

Persons Experiencing Homelessness during Extreme Temperatures: Lessons for Promoting Socially Inclusive Adaptive Capacity

Climate change and increasing extreme temperatures present unique challenges to persons experiencing homelessness (PEH), including heightened physical and psychological harm. While green and urban infrastructure has emerged as one possible mitigation strategy, homeless populations are rarely included in municipal disaster planning or infrastructure research. This study used in-depth interviews with PEH (N = 42) during the summers of 2022 and 2023. Questions were designed around phenomenological methods to explore the individuals' firsthand descriptions of the lived experience of coping during extreme temperatures within a mid-size city in the Southeastern United States. Our findings highlight how social exclusion within the built environment reduces PEH's adaptive capacity and increases the physical and psychological risks of extreme temperatures, namely through limiting and policing scarce resources and restricting the mobility of PEH. In contrast, public transit provided relief from extreme temperatures. Implications from our findings include the need for attention on inclusive green urban infrastructure, including increased placement and access to shade, public water, mixed-use daytime sheltering models, and the installation of lockers to increase capacity to maintain supplies and gear necessary for enduring extreme temperatures. Findings also highlight the challenges of designing inclusive green infrastructure and the importance of de-stigmatizing homelessness and building more housing and income support to increase adaptive capacity for an entire community in the context of a rapidly warming climate.

Invisible struggles: WASH insecurity and implications of extreme weather among urban homeless in high-income countries - A systematic scoping review

This paper aims to provide a deeper understanding of the water-, sanitation- and hygiene (WASH)-related insecurities that people experiencing homelessness in urban areas of high-income countries (HIC) are facing, and how these insecurities are further complicated during extreme weather events. While limited recent research has looked into WASH among people experiencing homelessness in HICs, and while some work has considering the implications of climate change on WASH and health, the nexus of WASH, extreme weather events and homelessness in HICs have not been studied thus far. We conducted the first systematic scoping review of peer-reviewed literature on this nexus, which is understudied and marked by complexity, involving a range of systems and forms of impact. A total of 50 publications were included in our analysis. We found that public facilities like drinking water fountains, toilets, handwashing facilities, and showers are scarce, frequently unavailable, often pose safety and cleanliness issues, and access to non-public facilities may be cost-prohibitive for homeless populations. Consequently, people experiencing homelessness, including those sleeping rough, in encampments, or shelters, are often forced to limit drinking water consumption, forego healthy hygiene behaviours, and resort to open urination and defecation, all of which carry health risks. Extreme weather events, like heatwaves, extreme cold, heavy rain and flooding exacerbate challenges for people experiencing homelessness, further complicating their access to WASH, and reducing the ability of service providers to deliver extra relief, creating a dual WASH and health burden. Our review highlights that the Human Right to Water and Sanitation is not met for people experiencing homelessness in urban areas of high-income countries, with women emerging as one of the most vulnerable subgroups. It reveals that the impact of certain WASH issues (e.g. drinking water) on homeless populations are better understood than others (e.g. waste), and, similarly, the effects of certain extreme weather events (e.g. heatwaves) on the health and WASH conditions of people experiencing homelessness are better understood than others (e.g. flooding). Data gaps and the lack of information on limited WASH access and health circumstances of people experiencing homelessness, further minimize their representation and consequently impose obstacles to improve their situation. Based on our analysis, we established a framework which operationalizes the nexus of WASH, extreme weather events and homelessness. This framework improves our understanding of the underlying complexities at the intersection of these three issues and provides a foundation for enhanced preparedness and health-oriented planning.

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

Objective

Heat vulnerability and homelessness are central public health concerns in cities globally, and public health implementation should address these two challenges in tandem to minimize preventable heat-related morbidity and mortality. Populations facing unsheltered homelessness use tents (or similar shelters) with shading features to minimize sun and heat exposure. This study evaluates the efficacy of different tent cover (shading) materials and how they moderate the in-tent air temperature (Tair) exposures of tent users during extreme summer conditions.

Study design

Within-tent Tair monitoring using Kestrel Drop devices occurred across three full typical summer days in Phoenix, Arizona in July 2022.

Methods

In-tent Tair were statistically compared between six small side-by-side identical tents with different cover materials (control (no cover), mylar, white bedsheet, tarp, sunbrella fabric, aluminum foil), as well as with ambient Tair.

Results

Using any tent resulted in higher daytime in-tent Tair than ambient Tair. Further, compared to a control tent, the Tair within tents shaded with sunbrella, tarp, and white bedsheet had significantly higher Tair at all times (2.36 °C, 2.46 °C, and 1.11 °C higher Tair, respectively), controlling for Tair and day/night.

Conclusion

Adding cover materials over tents may increase heat risk to an already vulnerable population at certain times of the day. Higher in-tent Tair is attributable to the reduced ability for heat and vapor to escape, largely due to reduced ventilation (mixing). Local authorities and welfare associations should reconsider using unventilated tents for shading and promote more widespread, ventilated tents and shade to ensure that prevention efforts do not further marginalize the most vulnerable. Future work should incorporate more comprehensive measurements of solar radiation to quantify overall heat stress for exposure reduction techniques.

The application of GIS in homelessness research and service delivery: A qualitative systematic review

GIS is increasingly popular in the study of complex social issues, such as homelessness. This study aims to assess how GIS has been leveraged and applied to homelessness research and service delivery. Systematic searching of sixteen databases was completed between January and March of 2021 using the terms "homeless" and "Geospatial Information Systems (GIS)." A final sample of 19 sources were identified from a total of 1719 identified sources. Through quantitative and qualitative methods, the included sources examined 1) static location characteristics associated with homelessness, and 2) mobility of homeless persons.

Managing the unexpected: The role of homeless service providers during the 2017-2018 California wildfires

People experiencing homelessness during the 2017-2018 California wildfires faced significant risks of disruption. Homeless service organizations (HSOs) are an essential safety net for this population. To learn about how HSOs performed during the wildfires, this study interviewed U.S. Department of Veterans Affairs (VA) staff overseeing HSOs providing transitional housing under the VA's Grant and Per Diem (GPD) program to Veterans experiencing homelessness. We employed a comparative case study approach exploring GPD organizations' disaster response actions, including evacuating Veterans from wildfire-affected areas or taking in disaster-displaced Veterans. This article presents three themes in the GPD organizations' disaster response: (1) Organizations benefitted from close collaboration and communication with the VA during the disaster, creating a safety net to ensure Veterans' well-being and enact rapid re-housing to prevent homelessness; (2) Organization staff performed heroically under stressful disaster conditions; and (3) Organizations benefitted from the written disaster plans that VA requires them to create, but were not as well-prepared for wildfires as they had been for earthquakes. As emergent threats such as the COVID-19 pandemic, wildfires, and a very active 2020 hurricane season amplify the importance of mitigating risks, comprehensive disaster planning is needed to ensure the safety and support of people experiencing homelessness.

Climate Change, Weather, Housing Precarity, and Homelessness: A Systematic Review of Reviews

This systematic review of reviews was conducted to examine housing precarity and homelessness in relation to climate change and weather extremes internationally. In a thematic analysis of 15 reviews (5 systematic and 10 non-systematic), the following themes emerged: risk factors for homelessness/housing precarity, temperature extremes, health concerns, structural factors, natural disasters, and housing. First, an increased risk of homelessness has been found for people who are vulnerably housed and populations in lower socio-economic positions due to energy insecurity and climate change-induced natural hazards. Second, homeless/vulnerably-housed populations are disproportionately exposed to climatic events (temperature extremes and natural disasters). Third, the physical and mental health of homeless/vulnerably-housed populations is projected to be impacted by weather extremes and climate change. Fourth, while green infrastructure may have positive effects for homeless/vulnerably-housed populations, housing remains a major concern in urban environments. Finally, structural changes must be implemented. Recommendations for addressing the impact of climate change on homelessness and housing precarity were generated, including interventions focusing on homelessness/housing precarity and reducing the effects of weather extremes, improved housing and urban planning, and further research on homelessness/housing precarity and climate change. To further enhance the impact of these initiatives, we suggest employing the Human Rights-Based Approach (HRBA).

Fostering Trust With a Young Man Experiencing Homelessness and Advanced Cancer

Persons experiencing homelessness (PEH) face countless barriers to equitable health, social, and palliative care across all settings. Brandon was a 23-year-old male, well-spoken, groomed, and polite despite difficult circumstances. He was severely abused then abandoned as a child, living in multiple foster homes until 18. With no consistent caring adult figure, he predictably fell into a chaotic lifestyle, had 3 children by different mothers, and became homeless in New York City. He presented with newly diagnosed renal cell carcinoma metastatic to lung, lymph nodes, and bone. Spine and pelvic metastases caused paralyzing somatic pain that interfered with walking and sitting and prevented Brandon from performing the activities of daily living essential for his survival on the streets and safekeeping of opioids. Lack of basic social support and a history of multiple abandonments made a care plan for this young, homeless, and truly isolated man very challenging. The inpatient and outpatient interdisciplinary team members partnering with Brandon each earned his trust with time. A "safe place" opened hearts on all sides of the therapeutic relationship and led to a plan that was acceptable for both the patient and the palliative care team. Clinicians are often challenged to provide sustained and pragmatic palliative care services for PEH due to complex barriers. Continued advocacy for equitable and tailored services that ensure high-quality palliative care for PEH is critical at individual, institutional, and system levels to promote health equity and dignified care.