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Indoor residential environments will be an increasing source of dangerous heat exposure as summer temperatures rise. Although air conditioning is a recognized preventative measure, many vulnerable residents either lack air conditioning or cannot always afford the electricity. Understanding the relative influence of different building characteristics and percentages of tree canopy coverage on indoor air temperatures during extreme heat events can help prioritize intervention strategies. We measured indoor and outdoor temperatures at 140 homes in Detroit (MI), Atlanta (GA), and Phoenix (AZ) and surveyed residents to determine the presence of a working central air-conditioning system and their ability to afford utilities. For each home, we collected information on construction year, interior size, single versus multifamily structure, façade type, and percentage of tree canopy. After air conditioning, the importance of building characteristics versus tree canopy measures varied by city. In Detroit, masonry façades worsened the influence of outdoor temperatures, whereas increased tree canopy coverage moderated the influence. In Atlanta, building characteristics were not significant, but tree canopy moderated indoor temperatures in late afternoon. In Phoenix, some building characteristics moderated the influence of outdoor temperatures in late afternoon. In Detroit, only 35% of respondents had and used central air conditioning as needed compared with 57% in Atlanta and 95% in Phoenix. The influence of tree canopy and building characteristics on indoor temperatures varied by city depending on its background climate. We recommend adding questions about air conditioning and utility poverty to the U.S. Census. For rental properties, municipalities should establish and enforce maximum indoor temperature thresholds. States should include cooling in their Low Income Home Energy Assistance (LIHEAP) programs. Public cooling centers need to anticipate electricity outages. Urban planners must ensure efforts to increase mechanical cooling are powered by renewable energy sources. [ABSTRACT FROM AUTHOR]

Extreme heat events induced by climate change present a growing risk to transit passenger comfort and health. To reduce exposure, agencies may consider changes to schedules that reduce headways on heavily trafficked bus routes serving vulnerable populations. This paper develops a schedule optimization model to minimize heat exposure and applies it to local bus services in Phoenix, Arizona, using agent-based simulation to inform travel demand and rider characteristics. Rerouting as little as 10% of a fleet is found to reduce network-wide exposure by as much as 35% when operating at maximum fleet capacity. Outcome improvements are notably characterized by diminishing returns, owing to skewed ridership and the inverse relationship between fleet size and passenger wait time. Access to spare vehicles can also ensure significant reductions in exposure, especially under the most extreme temperatures. Rerouting, therefore, presents a low-cost, adaptable resilience strategy to protect riders from extreme heat exposure. [ABSTRACT FROM AUTHOR]

Many cities aim to progress toward their sustainability and public health goals by increasing use of their public transit systems. However, without adequate protective infrastructure that provides thermally comfortable conditions for public transit riders, it can be challenging to reach these goals in hot climates. We took micrometeorological measurements and surveyed riders about their perceptions of heat and heat-coping behaviors at bus stops with a variety of design attributes in Phoenix, AZ, USA, during the summer of 2018. We identified the design attributes and coping behaviors that made riders feel cooler. We observed that current infrastructure standards and material choices for bus stops in Phoenix are insufficient to provide thermal comfort, and can even expose riders to health risks. Almost half of the study participants felt hot or very hot at the time they were surveyed, and more than half reported feeling thermally uncomfortable. On average, shade reduced the physiological equivalent temperature (PET) by 19 °C. Moreover, we found significant diurnal differences in PET reductions from the shade provided by various design attributes. For instance, all design attributes were effective in reducing PET in the morning; however, a vegetated awning did not provide statistically significant shade reductions in the afternoon. Temperatures of sun-exposed surfaces of man-made materials exceeded skin burn thresholds in the afternoon, but shade was effective in bringing the same surfaces to safe levels. Aesthetically pleasing stops were rated as cooler than stops rated as less beautiful. We conclude that cities striving to increase public transit use should prioritize thermal comfort when designing public transit stops in hot climates. [ABSTRACT FROM AUTHOR]

• Neighborhood satisfaction increased with xeric landscaping and proximity to the desert. • The effects of desert landscapes are positive irrespective of landscaping preference. • Satisfaction was positively associated with yard management intensity for people with mesic landscaping preferences. • People living in neighborhoods with the highest levels of satisfaction also intensively managed their yards. Residential landscapes support human well-being and ecological functioning in urban ecosystems. Trees and native plants in yards and neighborhoods positively influence satisfaction, an important component of human well-being and quality of life. However, these patterns may not hold true in arid ecoregions, where the composition of desert vegetation contrasts the tall, broad-leafed trees of temperate regions. The effects of xeric, desert-like landscaping on satisfaction with the neighborhood environment are especially important to consider given the large amount of resources required to support people's propensity for grassy yards. Although place satisfaction is related to pro-environmental behavior, the multi-scalar relationship between yard management decisions and satisfaction with the neighborhood environment has yet to be established. Here, we test the social-ecological dynamics of landscape preferences, satisfaction with trees and desert plants, and management intensity in residential yards and neighborhoods throughout the desert city of Phoenix, Arizona, USA. We found that wealthy neighborhoods close to desert open space were intensively managed and supported the highest levels of satisfaction. However, there was no direct relationship between satisfaction and management intensity for people who preferred xeric landscaping. Instead, management intensity for people with xeric preferences was related to demographics, such as income and home ownership. There was a relationship between satisfaction and management intensity for people with mesic preferences, suggesting a resource cost to maintain satisfaction for lush, green landscaping in a desert city. Overall, our study supports the assertion that changing yard landscaping may not result in desired changes for high-input management practices. [ABSTRACT FROM AUTHOR]

• Environmental heat exposure considerably varies between individuals. • Time spent outdoors was moderately associated with personal heat exposure. • Income and vulnerability were weakly associated with personal heat exposure. • Weather station observations and personal heat exposure were poorly correlated. A more precise understanding of individual-level heat exposure may be helpful to advance knowledge about heat-health impacts and effective intervention strategies, especially in light of projected increases in the severity and frequency of extreme heat events. We developed and interrogated different metrics for quantifying personal heat exposure and explored their association with social risk factors. To do so, we collected simultaneous personal heat exposure data from 64 residents of metropolitan Phoenix, Arizona. From these data, we derived five exposure metrics: Mean Individually Experienced Temperature (IET), Maximum IET, Longest Exposure Period (LEP), Percentage Minutes Above Threshold (PMAT), and Degree Minutes Above Threshold (DMAT), and calculated each for Day Hours, Night Hours, and All Hours of the study period. We then calculated effect sizes for the associations between those metrics and four social risk factors: neighborhood vulnerability, income, home cooling type, and time spent outside. We also investigated exposure misclassification by constructing linear regression models of observations from a regional weather station and hourly IET for each participant. Our analysis revealed that metric choice and timeframe added depth and nuance to our understanding of differences in exposure within and between populations. We found that time spent outside and income were the two risk factors most strongly associated with personal heat exposure. We also found evidence that Mean IET is a good, but perhaps not optimal, measure for assessing group differences in exposure. Most participants' IETs were poorly correlated with regional weather station observations and the slope and correlation coefficient for linear regression models between regional weather station data and IETs varied widely among participants. We recommend continued efforts to investigate personal heat exposure, especially in combination with physiological indicators, to improve our understanding of links between ambient temperatures, social risk factors, and health outcomes. [ABSTRACT FROM AUTHOR]

The causes and consequences of indoor heat exposure are receiving growing attention as global temperature rises and people seek respite from the heat in indoor spaces. In this study, we measured indoor temperatures of 46 air-conditioned residences in Phoenix, Arizona, United States. Temperatures were collected concurrently at 5-min intervals from August 21 to September 19, 2016. Indoor temperatures exhibited significant heterogeneity across all residences, ranging from 16.5 to 37.2 °C with a mean (SD) of 26.4 °C (2.2 °C). On average, the 5-min indoor temperatures were moderately correlated with outdoor temperature (r = 0.421), although individual household correlations were highly variable, ranging from r = -0.244 to r = 0.924. Households were grouped into six clusters using K-means based on 19 temperature metrics. We tested for differences in demographic, behavior, and infrastructure indicators between those six clusters based on responses to a social survey. Nearly half the variance in preferred thermostat setting was explained by cluster (R 2 = 0.455, p <.001). For the most part, measures of air-conditioning use, limitations on air-conditioning use, and household resources (e.g., income) did not vary significantly by cluster. The same was true for heat-related health and comfort outcomes. Two households that did not pay their own electric bill were by far the coldest homes (average temperature of 20.0 °C). We conclude that indoor temperature preference may supersede concerns related to the cost of using air-conditioning and that resource-constrained households may be sacrificing other necessities to keep their homes comfortable. • Indoor air temperatures of centrally air-conditioned homes are heterogeneous. • Indoor temperature metrics were used to classify households into six clusters. • Thermal preference was related to cluster; income and heat outcomes were not. • Households that did not pay their own electric bills were the coldest. • Resource-constrained households may sacrifice more to keep their home comfortable. [ABSTRACT FROM AUTHOR]

Climate change is poised to significantly increase people's heat exposure, yet there remain limited insights into how individuals experience heat in the conjunction of behavior and infrastructure. We developed a simulation platform - Icarus - to estimate traveler's heat exposure at both personal and population scales at the interface of travel behavior, microclimate, and the built environment. Icarus is applied to the Phoenix metropolitan region as a case study using three different temperature measurements: air temperature (T air), mean radiant temperature (T MRT), and wet bulb globe temperature (T WBGT). The case study analysis shows that travel patterns (such as trip duration and the trip start time) for different demographic groups affect personal and population heat exposure. Different temperature measures also resulted in widely varying estimates of personal heat exposure. [ABSTRACT FROM AUTHOR]

Increasing urban temperatures pose a public health threat and, in many cities, there is a disparity among neighborhoods with respect to access to cooling benefits. Residents may be unable to afford to operate cooling systems, and underserved communities are less likely and/or able to advocate for heat-reducing solutions. There is also a significant gap between adaptation theory and practice. This gap could be diminished by better understanding the barriers and limits to adaptation processes. This paper presents the Nature's Cooling Systems project's community engagement methodology, which aims to empower underserved communities to shift those dynamics. Through this process, we sought to learn about key urban heat adaptation barriers at the neighborhood scale. The methodology was piloted in three neighborhoods in metropolitan Phoenix to provide better thermal comfort in the hottest and highest-need neighborhoods. Barriers to adaptation strategies that emerged from these workshops overlapped with those articulated in the literature, including detecting and defining the problem, increasing information use, and developing, assessing, and selecting options. This methodology can serve as a model for community-driven heat adaptation planning for other neighborhoods facing increasing heat. Attention to key barriers is critical for success of adaptation measures. • Community engagement methodology produces hyper-local heat action plans. • Urban heat solutions include community-owned tree program/shade location priorities. • Residents seek urban-specific heat safety program to combat public health issues. • This methodology grows a neighborhood's ability to keep cool despite urban heat. • Neighborhoods show increased social cohesion as a result of the workshops. [ABSTRACT FROM AUTHOR]

Research on ecosystem services (ES) has largely focused on the ecological functions that produce services or the economic valuation of the benefits provided by ecosystems. Far less research has examined public perceptions of ES, and more so ecosystem disservices (EDS), despite evidence that ecosystem properties and functions can produce beneficial or detrimental outcomes for human well-being. To address this gap, we present a robust approach to measuring beliefs about ecosystem services and disservices. With various means to confirm the validity and reliability of ES and EDS measures, we demonstrate this approach with survey data that captures residents' perceptions about whether their local neighborhood environment (as the ecosystem of focus) provides certain positive or negative impacts in metropolitan Phoenix, Arizona. The results highlight patterns in people's views of: desirable and undesirable biota; benefits and risks pertaining to heat and stormwater; recreational and aesthetic values; and societal nuisances and problems. Composite survey scales for overall perceptions of services and disservices are presented, in addition to more distinctive dimensions of ES and EDS. To better understand and manage ecosystems for diverse benefits, the specific survey measures and the general methodological approach can be adapted to various ecosystems and contexts. [ABSTRACT FROM AUTHOR]

Practitioners and researchers use vulnerability indices to understand the conditions that influence hazard risk. However, there has been little research on how well such indices depict household-scale vulnerability to specific hazards. We examined relationships between an all-hazard index and a hazard-specific index with household-level adaptive resources, adaptive behaviors, proximate sensitivities, and self-reported health outcomes related to extreme heat. Household measures were drawn from a stratified random sample survey conducted in Phoenix, Arizona, USA (n = 163). The results point to different experiences between households in more and less heat vulnerable areas. The largest differences between households stratified by the hazard-specific index (Heat Vulnerability Index) primarily involved adaptive resources and behaviors, whereas indicators of proximate sensitivity were more strongly differentiated by the all-hazard index (Social Vulnerability Index). Differences in health outcomes between more and less vulnerable neighborhoods were more evident using HVI than SoVI, although effect sizes using either index were small and confidence intervals were wide. The relationship between vulnerability indices and several survey measures varied across four study sites. The specific ways in which more and less vulnerable communities differ from one another varies based on the adaptation, sensitivity, or outcome measure of interest, location within the city, and choice of vulnerability index. • Vulnerability indices are inconsistently associated with household experiences with heat. • Associations between experiences with heat and vulnerability indices vary spatially. • Highly vulnerable homes compensate for restricted use of central AC with other cooling devices. • Most self-reported health outcomes were not closely related to SoVI or HVI. [ABSTRACT FROM AUTHOR]