Age Modulates Physiological Responses during Fan Use under Extreme Heat and Humidity

Gagnon, Daniel; Romero, Steven A.; Cramer, Matthew N.; Kouda, Ken; Poh, Paula Y.S.; Ngo, Hai T.; Jay, Ollie; Crandall, Craig G.

doi:10.1249/mss.0000000000001348

Cited by 33 publications

(25 citation statements)

References 34 publications

(63 reference statements)

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“…The data were collected as part of a larger study examining the effect of fan use in young and older adults during exposure to extreme heat and humidity. The results of the control condition presented herein have been published previously (Gagnon et al., ; Gagnon et al., ), but relevant data are included to specifically evaluate the effect of folic acid supplementation. Participants were non‐smokers, free of known cardiovascular, respiratory, neurological or metabolic diseases and were not taking any related medications.…”

Section: Methodsmentioning

confidence: 99%

“…Brachial artery diameter and blood velocity were measured from 1‐min recordings at baseline and every other stage during the humidity ramp protocol. Brachial artery blood velocity was measured from Doppler ultrasound audio recordings using a validated intensity‐weighed algorithm (DUC 2 software), subsequent to demodulation of forward and reverse Doppler frequencies (Buck, Sieck, & Halliwill, ), as previously performed in our laboratory (Gagnon et al., ; Romero et al ., 2017). Longitudinal B‐mode images of the brachial artery were used to measure diameter at end‐diastole using on‐screen callipers.…”

Section: Methodsmentioning

confidence: 99%

“…Forearm vascular conductance was subsequently calculated as forearm blood flow divided by mean arterial pressure and expressed as an absolute value (ml min −1 mmHg −1 ). The critical humidity at which elevations in heart rate and oesophageal temperature occurred was determined using segmented regression analysis (Gagnon et al., , ; Ravanelli et al., ). Dry heat exchange (W m −2 ) was calculated as the sum of convective and radiant heat exchanges which were estimated using partitional calorimetry, as previously described (Ravanelli et al., ).…”

Section: Methodsmentioning

confidence: 99%

“…We recently evaluated the effect of electric fan use on cardiovascular and thermoregulatory responses of healthy older adults exposed to extreme heat and humidity (Gagnon et al., ; Gagnon, Romero, Cramer, Jay, & Crandall, ). Since rates of heat exchange are proportional to air velocity, fan use elevates both dry and evaporative heat exchange between the body and the environment (Jay, Cramer, Ravanelli, & Hodder, ; Ravanelli, Gagnon, Hodder, Havenith, & Jay, ).…”

Section: Introductionmentioning

confidence: 99%

“…However, fan use during extreme heat exposure exacerbates thermoregulatory and cardiovascular strain in older adults (Gagnon et al., ). The negative effect of fan use in older adults is likely related to a diminished sweating capacity, such that a greater rate of dry heat gain with fan use is not compensated for by additional sweat evaporation (Gagnon & Crandall, ; Gagnon et al ., 2017). As such, alternative interventions are needed to alleviate thermoregulatory and cardiovascular strain of older adults during extreme heat exposure.…”

Section: Introductionmentioning

confidence: 99%

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Folic acid supplementation does not attenuate thermoregulatory or cardiovascular strain of older adults exposed to extreme heat and humidity

Gagnon

Romero

Cramer

et al. 2018

Experimental Physiology

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Folic acid supplementation reverses age-related reductions in cutaneous vasodilatation during passive heating. However, it is unknown if folic acid supplementation alleviates thermoregulatory and cardiovascular strain experienced by older adults during heat exposure. We evaluated the effect of folic acid supplementation on thermoregulatory and cardiovascular responses of nine healthy older adults (61-72 years, 3 males/6 females) exposed to extreme heat and humidity. Participants rested at 42°C while relative humidity was increased from 30% to 70% in 2% increments every 5 min. The protocol was performed before (CON) and after (FOLIC) 6 weeks of folic acid supplementation (5 mg day ). Local cutaneous vascular conductance (CVC, laser-Doppler flowmetry), forearm vascular conductance (FVC, Doppler ultrasound), mean skin and oesophageal temperatures, heart rate, blood pressure and cardiac output were measured. Folic acid supplementation increased fasting serum folate concentrations (P < 0.01). Absolute CVC was greater throughout the protocol following supplementation (CON: 1.29 ± 0.16 units mmHg vs. FOLIC: 1.65 ± 0.24 units mmHg , P < 0.01). However, normalized CVC (CON: 54 ± 8% vs. FOLIC: 59 ± 7%, P = 0.22), FVC (CON: 3.47 ± 0.76 ml mmHg vs. FOLIC: 3.40 ± 0.56 ml mmHg , P = 0.93), mean skin (P = 0.81) and oesophageal (CON: 36.87 ± 0.28°C vs. folic: 36.90 ± 0.25°C, P = 0.98) temperatures, heart rate (CON: 83 ± 10 beats min vs. FOLIC: 84 ± 8 beats min , P = 0.64), blood pressure (P = 0.71) and cardiac output (P = 0.20) were unaffected by folic acid supplementation. These results demonstrate that 6 weeks of folic acid supplementation does not alleviate thermoregulatory or cardiovascular strain of healthy older adults exposed to extreme heat and humidity.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Folic acid supplementation does not attenuate thermoregulatory or cardiovascular strain of older adults exposed to extreme heat and humidity

Gagnon

Romero

Cramer

et al. 2018

Experimental Physiology

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Integrated Assessment of Urban Overheating Impacts on Human Life

Nazarian

Krayenhoff

Bechtel

et al. 2021

Preprint

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Urban overheating, driven by global climate change and urban development, is a major contemporary challenge that substantially impacts urban livability and sustainability. Overheating represents a multifaceted threat to the well-being, performance, and health of individuals as well as the energy efficiency and economy of cities, and it is influenced by complex interactions between building, city, and global scale climates. In recent decades, extensive discipline-specific research has characterized urban heat and assessed its implications on human life, including ongoing efforts to bridge neighboring disciplines. The research horizon now encompasses complex problems involving a wide range of disciplines, and therefore comprehensive and integrated assessments are needed that address such interdisciplinarity. Here, our objective is to go beyond a review of existing literature and instead provide a broad overview and integrated assessments of urban overheating, defining holistic pathways for addressing the impacts on human life. We (a) detail the characterization of heat hazards and exposure across different scales and in various disciplines, (b) identify individual sensitivities to urban overheating that increase vulnerability and cause adverse impacts in different populations, (c) elaborate on adaptive capacities that individuals and cities can adopt, (d) document the impacts of urban overheating on health and energy, and (e) discuss frontiers of theoretical and applied urban climatology, built environment design, and governance toward reduction of heat exposure and vulnerability at various scales. The most critical challenges in future research and application are identified, targeting both the gaps and the need for greater integration in overheating assessments.Plain Language Summary Many major cities are faced with the compounding effects of climate change and rapid urbanization. One of the main challenges that result is urban overheating, which leads to negative impacts on human life (deteriorating health, productivity, and well-being) and urban energy systems. Heat exposure in cities, however, is only the trigger and there are other factors that influence impacts. Urban heat vulnerability exists when sensitive people and infrastructure are exposed to extreme heat, and negative impacts ensue if there is a lack of capacity to respond and adapt. Accordingly, to combat overheating challenges, it is critical that multidisciplinary solutions are integrated to mitigate exposure, reduce sensitivity, and increase adaptive capacities. This paper provides an integrated assessment of urban overheating literature, defining pathways for addressing the impacts on human life. We review the state-of-the-art methods used to quantify heat hazards and exposure, detail the sensitivity of people and infrastructure to overheating, and elaborate on the adaptive capacities that individuals and cities can undertake in response. We provide recommendations for both researchers and policymakers that will minimize overheating impacts. Thes...

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