Heat-Moderating Effects of Bus Stop Shelters and Tree Shade on Public Transport Ridership

Efficacy of Cooling Centers for Mitigating Physiological Strain in Older Adults during Daylong Heat Exposure: A Laboratory-Based Heat Wave Simulation

BACKGROUND

Health agencies, including the U.S. Centers for Disease Control and Prevention and the World Health Organization, recommend that heat-vulnerable older adults without home air-conditioning should visit cooling centers or other air-conditioned locations (e.g., a shopping mall) during heat waves. However, experimental evidence supporting the effectiveness of brief air-conditioning is lacking.

OBJECTIVE

We evaluated whether brief exposure to an air-conditioned environment, as experienced in a cooling center, was effective for limiting physiological strain in older adults during a daylong laboratory-based heat wave simulation.

METHODS

Forty adults 64-79 years of age underwent a 9-h simulated heat wave (heat index: 37°C) with (cooling group, n=20) or without (control group, n=20) a cooling intervention consisting of 2-h rest in an air-conditioned room (∼23°C, hours 5-6). Core and skin temperatures, whole-body heat exchange and storage, cardiovascular function, and circulating markers of acute inflammation were assessed.

RESULTS

Core temperature was 0.8°C (95% CI: 0.6, 0.9) lower in the cooling group compared with the control group at the end of the cooling intervention (p<0.001; hour 6), and it remained 0.3°C (95% CI: 0.2, 0.4) lower an hour after returning to the heat (p<0.001; hour 7). Despite this, core temperatures in each group were statistically equivalent at hours 8 and 9, within ±0.3°C (p≤0.005). Cooling also acutely reduced demand on the heart and improved indices of cardiovascular autonomic function (p≤0.021); however, these outcomes were not different between groups at the end of exposure (p≥0.58).

DISCUSSION

Brief air-conditioning exposure during a simulated heat wave caused a robust but transient reduction in core temperature and cardiovascular strain. These findings provide important experimental support for national and international guidance that cooling centers are effective for limiting physiological strain during heat waves. However, they also show that the physiological impacts of brief cooling are temporary, a factor that has not been considered in guidance issued by health agencies. https://doi.org/10.1289/EHP11651.

A direct observation tool to measure interactions between shade, nature, and children's physical activity: SOPLAY-SN

BACKGROUND

Most physical activity (PA) during school occurs at recess; however, recess PA may be influenced by children's thermal comfort and interaction with nature, neither of which have concurrently been measured reliably in previous studies. This study tests the reliability of SOPLAY-SN, an adaption of the validated System for Observing Play and Leisure Activity in Youth (SOPLAY) to measure Shade and Nature (SN) alongside PA, and associations between children's PA and interaction with shade and nature during recess to highlight the utility of the tool.

METHODS

Interactions with shade and nature were measured using systematic direct observation at two playgrounds (primary-grade = ages 5-8, upper-grade = ages 9-12) during recess at an elementary school in Phoenix, Arizona (USA). Pairs conducted observations over four warm days (primary = 29-34 °C, upper-grade = 32-36 °C) in May 2021 (N = 179 scans). Intraclass correlation coefficients (ICC) were used to calculate inter-rater reliability. Mean counts, frequencies, and Kendall rank correlation coefficient tests were used to assess relations between PA level and interactions with shade and nature.

RESULTS

Reliability was good for sedentary behavior (ICC = 0.98); light PA (LPA; ICC = 0.80) and moderate-to-vigorous PA (MVPA; ICC = 0.94); shade interaction (ICC = 0.95); and nature interaction (ICC = 0.80) and average agreement was good (86% overall PA, 88% shade, 90% nature). Most (60%) primary-grade children were observed in the shade, with 64% under a covered play structure where children were mainly (47%) sedentary. Of the 11% of primary-grade students observed interacting with nature, 90% occurred in a grass field with trees. Among upper-grade children, 23% were observed in the shade with 53% in grass fields where 48% of play was light. Few (7%) upper-grade children were observed interacting with nature, with most instances (76%) in a grass field with trees. Among primary-grade children, shade was correlated with sedentary behavior (τ_b = 0.63, p < .05); LPA (τ_b = 0.39, p < .05); MVPA (τ_b = 0.56, p < .05); and nature interactions with sedentary behavior (τ_b = 0.16, p < .05). Among upper-grade children, shade was correlated with sedentary behavior (τ_b = 0.27, p < .05) and LPA (τ_b = 0.21, p < .05).

CONCLUSIONS

SOPLAY-SN is a reliable tool for measuring children's interaction with shade and nature and participation in PA. Understanding how shade and nature impact movement during recess can inform playground design for children's health and well-being.

Extreme Climate Shocks and Green Agricultural Development: Evidence from the 2008 Snow Disaster in China

Extreme climate shocks cause agricultural yield reductions and increase long-term climate risk, altering farmers’ long-term production decisions and affecting green agricultural development (GAD). We take the 2008 snow disaster in China as an extreme climate shock, calculate the GAD index by the entropy weighting method, and use the difference-in-difference method to study the extreme climate shock’s impact on GAD. The results show that: (1) Extreme climate shocks are detrimental to GAD, with the snow disaster decreasing China’s GAD level by 3.07%. (2) The impacts of extreme climate shocks are heterogeneous across climate and economic zones, with greater impact in humid and developed regions. (3) Extreme climate shocks affect GAD mainly by reducing farmers’ willingness to cultivate, and increasing energy consumption, fertilizer, and pesticide input. (4) Extreme climate shocks do not reduce agricultural yields in the long run. Still, they reduce the total value of agricultural production and decrease the quality of agricultural products expressed in terms of unit value. The findings of this study have policy implications for developing countries in coping with extreme climate shocks and promoting GAD.

Social Inequities in Urban Heat and Greenspace: Analyzing Climate Justice in Delhi, India

Climate change and rapid urbanization currently pose major challenges for equitable development in megacities of the Global South, such as Delhi, India. This study considers how urban social inequities are distributed in terms of burdens and benefits by quantifying exposure through an urban heat risk index (UHRI), and proximity to greenspace through the normalized difference vegetation index (NDVI), at the ward level in Delhi. Landsat derived remote sensing imagery for May and September 2011 is used in a sensitivity analysis of varying seasonal exposure. Multivariable models based on generalized estimating equations (GEEs) reveal significant statistical associations (p < 0.05) between UHRI/NDVI and several indicators of social vulnerability. For example, the proportions of children (β = 0.922, p = 0.024) and agricultural workers (β = 0.394, p = 0.016) are positively associated with the May UHRI, while the proportions of households with assets (β = -1.978, p = 0.017) and households with electricity (β = -0.605, p = 0.010) are negatively associated with the May UHRI. In contrast, the proportions of children (β = 0.001, p = 0.633) and agricultural workers (β = 0.002, p = 0.356) are not significantly associated with the May NDVI, while the proportions of households with assets (β = 0.013, p = 0.010) and those with electricity (β = 0.008, p = 0.006) are positively associated with the May NDVI. Our findings emphasize the need for future research and policies to consider how socially vulnerable groups are inequitably exposed to the impact of climate change-related urban heat without the mitigating effects of greenspace.