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Meade RD, Akerman AP, Notley SR, Kirby NV, Sigal RJ, Kenny GP. Effects of Daylong Exposure to Indoor Overheating on Thermal and Cardiovascular Strain in Older Adults: A Randomized Crossover Trial. Environ Health Perspect 2024; 132:27003. [PMID: 38329752 PMCID: PMC10852046 DOI: 10.1289/ehp13159] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 11/29/2023] [Accepted: 12/22/2023] [Indexed: 02/09/2024]
Abstract
BACKGROUND Health agencies recommend that homes of heat-vulnerable occupants (e.g., older adults) be maintained below 24-28°C to prevent heat-related mortality and morbidity. However, there is limited experimental evidence to support these recommendations. OBJECTIVE To aid in the development of evidence-based guidance on safe indoor temperatures for temperate continental climates, we evaluated surrogate physiological outcomes linked with heat-related mortality and morbidity in older adults during simulated indoor overheating. METHODS Sixteen older adults [six women; median age: 72 y, interquartile range (IQR): 70-73 y; body mass index: 24.6 ( IQR : 22.1 - 27.0 ) kg / m 2 ] from the Ottawa, Ontario, Canada, region (warm summer continental climate) completed four randomized, 8-h exposures to conditions experienced indoors during hot weather in continental climates (e.g., Ontario, Canada; 64 participant exposures). Ambient conditions simulated an air-conditioned environment (22°C; control), proposed indoor temperature upper limits (26°C), and temperatures experienced in homes without air-conditioning (31°C and 36°C). Core temperature (rectal) was monitored as the primary outcome; based on previous recommendations, between-condition differences > 0.3 ° C were considered clinically meaningful. RESULTS Compared with 22°C, core temperature was elevated to a meaningful extent in 31°C [+ 0 . 7 ° C ; 95% confidence interval (CI): 0.5, 0.8] and 36°C (+ 0 . 9 ° C ; 95% CI: 0.8, 1.1), but not 26°C (+ 0 . 2 ° C , 95% CI: 0.0, 0.3). Increasing ambient temperatures were also associated with elevated heart rate and reduced arterial blood pressure and heart rate variability at rest, as well as progressive impairments in cardiac and blood pressure responses to standing from supine. DISCUSSION Core temperature and cardiovascular strain were not appreciably altered following 8-h exposure to 26°C but increased progressively in conditions above this threshold. These data support proposals for the establishment of a 26°C indoor temperature upper limit for protecting vulnerable occupants residing in temperate continental climates from indoor overheating. https://doi.org/10.1289/EHP13159.
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Affiliation(s)
- Robert D. Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
- Harvard T.H. Chan School of Public Health, Harvard University, Boston, Massachusetts, USA
| | - Ashley P. Akerman
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Sean R. Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Nathalie V. Kirby
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Ronald J. Sigal
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
- Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Glen P. Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
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Foster J, McKenna ZJ, Atkins WC, Jarrard CP, Crandall CG. Identifying the Optimal Heat Exposure Metric for Predicting the Physiological Response to Dry or Humid Heat Stress in Young and Older Adults: A Randomized Controlled Study. Environ Health Perspect 2024; 132:17701. [PMID: 38214893 PMCID: PMC10786203 DOI: 10.1289/ehp13733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 10/31/2023] [Accepted: 11/27/2023] [Indexed: 01/13/2024]
Affiliation(s)
- Josh Foster
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Centre for Human and Applied Physiological Sciences, King’s College London, London, UK
| | - Zachary J. McKenna
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Whitey C. Atkins
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Caitlin P. Jarrard
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Applied Clinical Research Department, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Craig G. Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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Cheong SM, Gaynanova I. Sensing the impact of extreme heat on physical activity and sleep. Digit Health 2024; 10:20552076241241509. [PMID: 38528970 PMCID: PMC10962040 DOI: 10.1177/20552076241241509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/07/2024] [Indexed: 03/27/2024] Open
Abstract
Introduction This study assesses the person-specific impact of extreme heat on low-income households using wearable sensors. The focus is on the intensive and longitudinal assessment of physical activity and sleep with the rising person-specific ambient temperature. Methods This study recruited 30 participants in a low-income and predominantly Black community in Houston, Texas in August and September of 2022. Each participant wore on his/her wrist an accelerometer that recorded person-specific ambient temperature, sedentary behavior, physical activity intensity (low and moderate to vigorous), and sleep efficiency 24 h over 14 days. Mixed effects models were used to analyze associations among physical activity, sleep, and person-specific ambient temperature. Results The main findings include increased sedentary time, sleep impairment with the rise of person-level ambient temperature, and the mitigating role of AC. Conclusions Extreme heat negatively affects physical activity and sleep. The negative consequences are especially critical for those with limited use of AC in lower-income neighborhoods of color. Staying home with a high indoor temperature during hot days can lead to various adverse health outcomes including accelerated cognitive decline, higher cancer risk, and social isolation.
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Affiliation(s)
- So-Min Cheong
- Department of Public Service & Administration, Texas A&M University, College Station, TX, USA
| | - Irina Gaynanova
- Department of Biostatistics, University of Michigan, Ann Arbor, MI, USA
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Rony MKK, Alamgir HM. High temperatures on mental health: Recognizing the association and the need for proactive strategies-A perspective. Health Sci Rep 2023; 6:e1729. [PMID: 38059052 PMCID: PMC10696165 DOI: 10.1002/hsr2.1729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 09/28/2023] [Accepted: 11/05/2023] [Indexed: 12/08/2023] Open
Abstract
Background and Aims The influence of temperature on various aspects of daily life is often underestimated, and its effects on mental health are not widely recognized. Understanding and addressing the relationship between temperature and mental well-being is crucial in the context of climate change and rising global temperatures. This perspective aimed to investigate the effects of high temperatures on mental health and identify proactive strategies to mitigate these effects. Methods This perspective adopted a twofold approach, including a comprehensive literature review and socioecological framework. The literature review involved extensive searches across Google Scholar, PubMed, and Scopus to identify relevant, peer-reviewed articles, and reports from diverse disciplines. Results The perspective emphasized the significance of recognizing heat stress and its consequences on mental well-being. Chronic heat stress can lead to increased stress, anxiety, and cognitive impairment. Vulnerable populations include, the very young, older adults, and individuals with pre-existing mental health conditions. Socioeconomic factors can further exacerbate vulnerability, highlighting the need for tailored strategies to manage mental health challenges during high temperatures. Additionally, the article identified and discussed proactive coping strategies to minimize both the psychological and physical impacts of heat stress. Mindfulness, stress management techniques, and therapy are suggested as effective means for individuals to manage psychological distress. Conclusion Implementing preventive measures are essential steps in promoting mental wellness in high temperatures. Proactive strategies by addressing the physiological and psychological effects of heat and considering the specific needs of vulnerable populations can help individuals and communities navigate the challenges posed by rising temperatures and promote resilience and preserve their mental well-being.
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Affiliation(s)
- Moustaq Karim Khan Rony
- Department of Public HealthBangladesh Open UniversityGazipurBangladesh
- Department of Institute of Social Welfare and ResearchUniversity of DhakaDhakaBangladesh
| | - Hasnat M. Alamgir
- Department of Career & Professional Development Services (CPDS)Southeast UniversityDhakaBangladesh
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Foster J, Mckenna ZJ, Atkins WC, Jarrard CP, Crandall CG. Aging Increases Enterocyte Damage during a 3-Hour Exposure to Very Hot and Dry Heat: A Preliminary Study. Biology (Basel) 2023; 12:1088. [PMID: 37626974 PMCID: PMC10451985 DOI: 10.3390/biology12081088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 08/01/2023] [Accepted: 08/02/2023] [Indexed: 08/27/2023]
Abstract
Profound heat stress can damage the gastrointestinal barrier, leading to microbial translocation from the gut and subsequent systemic inflammation. Despite the greater vulnerability of older people to heat wave-related morbidity and mortality, it is unknown if age modulates gastrointestinal barrier damage and inflammation during heat stress. Therefore, the aim of this study was to determine if aging impacted enterocyte damage and systemic inflammatory responses to a 3-h exposure to very hot and dry (47 °C, 15% humidity) heat with accompanying activities of daily living (intermittent activity at 3 METS). Data from 16 young (age 21 to 39 years) and 16 older (age 65 to 76 years) humans were used to address this aim. In each group, log-transformed plasma concentrations of intestinal fatty acid binding protein (I-FABPlog), interleukin-8 (IL-8log), and tissue factor (TFlog) were assessed as indices of enterocyte damage, systemic inflammation, and blood coagulation, respectively, before and after the 3-h heat exposure. In the younger cohort, I-FABPlog concentration did not increase from pre to post heat exposure (p = 0.264, d = 0.20), although it was elevated in the older group (p = 0.014, d = 0.67). The magnitude of the increase in I-FABPlog was greater in the older participants (p = 0.084, d = 0.55). Across all participants, there was no correlation between the change in core temperature and the change in IFABPlog. There was no change in IL-8log in the younger group (p = 0.193, d = 0.23) following heat exposure, but we observed a decrease in IL-8log in the older group (p = 0.047, d = 0.48). TFlog decreased in the younger group (p = 0.071, d = 0.41), but did not change in the older group (p = 0.193, d = 0.15). Our data indicate that I-FABPlog concentration (an index of enterocyte damage) is increased in older humans during a 3-h extreme heat exposure. Future studies should determine whether this marker reflects increased gastrointestinal barrier permeability in older individuals during heat exposure.
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Affiliation(s)
- Josh Foster
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, The University of Texas Southwestern Medical Center, Dallas, TX 75231, USA; (Z.J.M.); (W.C.A.); (C.P.J.); (C.G.C.)
- Centre for Human and Applied Physiological Sciences, Faculty of Life Sciences and Medicine, King’s College London, London SE1 1UL, UK
| | - Zachary J. Mckenna
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, The University of Texas Southwestern Medical Center, Dallas, TX 75231, USA; (Z.J.M.); (W.C.A.); (C.P.J.); (C.G.C.)
| | - Whitley C. Atkins
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, The University of Texas Southwestern Medical Center, Dallas, TX 75231, USA; (Z.J.M.); (W.C.A.); (C.P.J.); (C.G.C.)
| | - Caitlin P. Jarrard
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, The University of Texas Southwestern Medical Center, Dallas, TX 75231, USA; (Z.J.M.); (W.C.A.); (C.P.J.); (C.G.C.)
| | - Craig G. Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, The University of Texas Southwestern Medical Center, Dallas, TX 75231, USA; (Z.J.M.); (W.C.A.); (C.P.J.); (C.G.C.)
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