High Heat Index Research Articles

Physical school closures as a public health response to high heat index in the Philippines: a critical perspective

Physical school closures as a public health response to high heat index in the Philippines: a critical perspective

Spatio-temporal patterns of heat index and heat-related Emergency Medical Services (EMS)

Despite growing concerns about heat waves due to climate change and their health impacts, there has been limited research on patterns of extreme heat during summertime and their association with heat-related Emergency Medical Services (EMS) incidents. This study examines spatiotemporal patterns of the heat index (HI) and its relationship to heat-related EMS incidents in Austin-Travis County, Texas, focusing on the summers of 2020 and 2021. Collecting 47,838 heat-related EMS incidence cases and aggregating them at the tract level (N = 290), the research employs spatiotemporal analysis, spatial autocorrelation, K-means clustering, and geographically weighted Poisson regression to identify disparities in heat-related health outcomes. Key findings indicate a significant correlation between high HI frequency and intensity and increased EMS incidents, particularly in East Austin, underscoring the area's heightened vulnerability to heat. The study also reveals that heat vulnerability and urban growth patterns are closely linked to the incidence of heat-related illnesses, and its impact varies by region. These results emphasize the critical need for targeted heat resilience strategies in urban planning and emergency response. This research merges socio-economic and environmental data to offer insights into heat-related health risks, informing targeted public health policies and urban planning for more equitable and effective interventions.

Heat index historical trends and projections due to climate change in the Mediterranean basin based on CMIP6

Air temperature and relative humidity can be considered as two essential meteorological parameters in the determination of heat stress. The heat index (HI) includes both of them and it is appropriate for determining the thermal conditions of different climates. We investigated potential changes in the HI for the Mediterranean basin using simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6) climate models under two future scenarios (Shared Socio-economic Pathways: SSP2-4.5 and SSP5-8.5) over the period 2020–2099. Results reveal an important increase of HI at the end of the 21st century for both scenarios, with greater changes for the SSP5-8.5 scenario all over the basin. Strong significant upwards trends (around 1 °C per decade; significance level computed at 5%) are expected in the entire area and for all months at the end of the century, with greatest values during the summer months (close to 1.5 °C per decade) along the coastal areas of the basin. Many areas of the Southern Mediterranean basin (Africa and Arabian Peninsula) will be strongly affected with dangerously high heat index values (higher than 41 °C) during summer months by the end of the 21st century. A northward extension of these dangerous conditions is also expected including several areas of southern Europe.

Severity Analysis for Occupational Heat-related Injury Using the Multinomial Logit Model

BackgroundWorkers are often exposed to hazardous heat due to their work environment, leading to various injuries. As a result of climate change, heat-related injuries (HRIs) are becoming more problematic. This study aims to identify critical contributing factors to the severity of occupational HRIs. MethodsThis study analyzed historical injury reports from the Occupational Safety and Health Administration (OSHA). Contributing factors to the severity of HRIs were identified using text mining and model-free machine learning methods. The Multinomial Logit Model (MNL) was applied to explore the relationship between impact factors and the severity of HRIs. ResultsThe results indicated a higher risk of fatal HRIs among middle-aged, older, and male workers, particularly in the construction, service, manufacturing, and agriculture industries. In addition, a higher heat index, collapses, heart attacks, and fall accidents increased the severity of HRIs, while symptoms such as dehydration, dizziness, cramps, faintness, and vomiting reduced the likelihood of fatal HRIs. ConclusionsThe severity of HRIs was significantly influenced by factors like workers’ age, gender, industry type, heat index , symptoms, and secondary injuries. The findings underscore the need for tailored preventive strategies and training across different worker groups to mitigate HRIs risks.

Exposure to ambient temperature and heat index in relation to DNA methylation age: A population-based study in Taiwan

BackgroundClimate change caused an increase in ambient temperature in the past decades. Exposure to high ambient temperature could result in biological aging, but relevant studies in a warm environment were lacking. We aimed to study the exposure effects of ambient temperature and heat index (HI) in relation to age acceleration in Taiwan, a subtropical island in Asia. MethodsThe study included 2,084 participants from Taiwan Biobank. Daily temperature and relative humidity data were collected from weather monitoring stations. Individual residential exposure was estimated by ordinary kriging. Moving averages of ambient temperature and HI from 1 to 180 days prior to enrollment were calculated to estimate the exposure effects in multiple time periods. Age acceleration was defined as the difference between DNA methylation age and chronological age. DNA methylation age was calculated by the Horvath’s, Hannum’s, Weidner’s, ELOVL2, FHL2, phenotypic (Pheno), Skin & blood, and GrimAge2 (Grim2) DNA methylation age algorithms. Multivariable linear regression models, generalized additive models (GAMs), and distributed lag non-linear models (DLNMs) were conducted to estimate the effects of ambient temperature and HI exposures in relation to age acceleration. ResultsExposure to high ambient temperature and HI were associated with increased age acceleration, and the associations were stronger in prolonged exposure. The heat stress days with maximum HI in caution (80-90°F), extreme caution (90-103°F), danger (103-124°F), and extreme danger (>124°F) were also associated with increased age acceleration, especially in the extreme danger days. Each extreme danger day was associated with 571.38 (95 % CI: 42.63–1100.13), 528.02 (95 % CI: 36.16–1019.87), 43.9 (95 % CI: 0.28–87.52), 16.82 (95 % CI: 2.36–31.28) and 15.52 (95 % CI: 2.17–28.88) days increase in the Horvath’s, Hannum’s, Weidner’s, Pheno, and Skin & blood age acceleration, respectively. ConclusionHigh ambient temperature and HI may accelerate biological aging.

Challenging the universality of heatwave definitions: gridded temperature discrepancies across climate regions

As global studies of climate change depict increasingly dire outcomes of extreme heat, there is an urgent need to understand the appropriateness of heatwave definitions and temperature datasets in different parts of the world. We carry out an intercomparison of the CHIRTS gridded station-satellite temperature dataset with three reanalysis products, ERA5, NCEP-DOE Reanalysis 2, and MERRA2, to assess biases in the absolute value of extreme heat events and the distribution of extreme events. We find close agreement between all four datasets in the magnitude and distribution of extreme temperatures, with a cold bias in the reanalyses over mountainous areas. However, there is little to no agreement between datasets on the timing of extreme heat events in the tropics, and the datasets do not even agree on which month is the hottest month climatologically in these regions. Second, we compare how the four datasets represent the frequency and timing of extreme heat events, using two different types of heatwave definitions: 5-day duration-based extremes and extreme temperature-humidity combinations (heat index). In the case of 5-day heatwaves, there are almost zero events recorded historically in tropical regions. In contrast, high absolute values of the heat index are most common in dry climates, likely due to the dominance of high temperature spikes in these regions, and high heat index events also occur in temperate and tropical regions. There is little agreement between datasets, however, on when these extreme heat index events have happened historically in the tropics. Given these results, we highlight the need for locally developed heatwave metrics for different parts of the world, and we urge against the use of a single heatwave definition in global studies. We also recommend that any studies assessing heat-health relationships in tropical regions beware of the lack of agreement between observational and reanalysis datasets and compare results from different gridded dataset products to estimate uncertainty in heat-health relationships.

Interactions of particulate matter with temperature, heat index and relative humidity on pediatric hand, foot, and mouth disease in a subtropical city

The associations of hand, foot, and mouth disease (HFMD) with meteorological variables and particulate matter (PM) remain controversial, and limited evidence is available on heat index (HI) and coarse particulate (PM10-2.5). Moreover, temperature and humidity are considered major risk factors but their interaction with PM remains unclear. We combined the distributed lag non-linear and quasi-Poisson models to estimate the non-linear and lagged associations of meteorological variables and PM with HFMD based on reported HFMD during 2015–2019 in Fuzhou, China. The multiplicative term of interaction was used to explore the relationship between HFMD and meteorological variables or PM at different levels of another variable. Stratified analyses were used to identify vulnerable subpopulations. We observed inverted-V-shaped relationships between HFMD and temperature and HI, and the W- and N-shaped for relative humidity (RH) and PM, respectively. Extreme high (i.e., the 95th percentile) temperature, HI and RH increased the HFMD with relative risks (RR) of 4.00 (95% confidence interval, 2.79–5.75), 2.20 (1.71–2.83) and 1.54 (1.35–1.75) referent to the minimum effect value of 10.3 °C, 69.4 and 54.8%, respectively. Higher concentrations of PM rapidly increased the HFMD. Infants under 2 years suffered more from temperature, HI and PM. There were synergistic effects between meteorological variables and PM on HFMD. For instance, the RRs of temperature (30 °C) and RH (40%) on HFMD increased from 3.68 (2.24–6.06) to 6.44 (4.29–9.66) and from 0.45 (0.14–1.47) to 2.15 (0.90–5.12) at low (<25%) and high (>75%) categories of PM2.5, respectively. While the RRs of 70 μg/m3 of PM10 and PM10-2.5 increased from 0.65 (0.32–1.31) to 2.93 (1.63–5.26) and from 0.86 (0.23–3.21) to 3.26 (1.23–8.62) at low and high categories of HI. These findings are essential for the development a prediction and warning systems and prevention and control strategies for HFMD.

Descriptive study of sweat dermatitis: A rare dermatoses not so rare in tropics

BackgroundSweat dermatitis is an irritant inflammatory dermatosis commonly encountered in tropics during summers. Profuse sweating triggered by high heat index, friction, clothing, outdoor activities, military training, overcrowding, prolonged working in ill-ventilated places, etc., are responsible or this dermatitis. Aim was to study the clinical, dermoscopic, vapometric, histopathological, and immunohistochemistry (IHC) findings in sweat dermatitis. MethodsTwenty-five patients of sweat dermatitis attending out-patient department (OPD) of tertiary care hospital, were recruited over a period of three months (June to August 2022). A detailed history was followed by dermatological examination, dermoscopy, vapometry, histopathology, and IHC studies. ResultsTwenty-five patients were included in the study. There was male preponderance with male: female ratio of 2.1:1. The mean age of patients was 30.36 years. Dermatological examination in all patients revealed brownish “parchment”-like, shiny “crinkled cellophane paper”-like patches over the entire upper back and shoulder region with areas of exfoliation. Dermoscopy revealed increased skin markings, deep brown pigmentary changes with superimposed whitish scales with islands of eroded skin, and prominent eccrine duct openings. Vapometric analysis revealed increased transepidermal water loss (TEWL) in the affected area in 88% of patients. Histopathological examination showed features of spongiotic dermatitis. IHC with CK7 (cytoplasmic) highlighted the normal eccrine coils. ConclusionSweat dermatitis is common seasonal dermatoses in tropics, but it remains undiagnosed due to lack of awareness. This study aims to sensitize medical doctors and dermatologists about sweat dermatitis and prevention strategies that can be helpful in mitigating it. The study also discusses the role of investigative modalities, such as dermoscopy, vapometry, histopathology, and IHC, in sweat dermatitis.

Simulation of Urban Heat Island during a High-Heat Event Using WRF Urban Canopy Models: A Case Study for Metro Manila

This present study aims to determine the performance of using the Weather Research and Forecasting (WRF) Model, coupled with the urban canopy models (UCMs), in simulating the 2 m air temperature and 2 m relative humidity in Metro Manila. The simulation was performed during a high heat event on 22–29 April 2018, which coincided with the dry season in the Philippines. The four urban canopy model options that were used in this study include, the bulk (no urban), SLUCM, BEP, and BEM. The results of the simulations were compared with the hourly observations from three weather stations over Metro Manila from the National Oceanic and Atmospheric Administration Integrated Surface Dataset (ISD) and one agrometeorological station in Naic, Cavite. After model validation, the urban heat island (UHI) was then characterized to determine the spatial-temporal variations in the cities of Metro Manila. Statistical results show that the WRF simulation for 2 m air temperature agrees with measurements with an RMSE of &lt;3.0 °C, mean bias error of &lt;2.0 °C, and index of agreement of &gt;0.80. WRF simulation for relative humidity still presents a challenge where simulation errors are higher than the acceptable range. The addition of UCMs does not necessarily improve the simulation for 2 m air temperature, while the use of BEP improved the 2 m relative humidity simulation. The results suggest the importance of using actual urban morphology values in WRF to accurately simulate near-surface variables. On the other hand, WRF simulation shows the presence of urban heat islands, notably in the northwest and central area of Metro Manila during daytime, extending throughout Metro Manila during nighttime. Lower air temperature was consistently observed in areas near Laguna Lake, while higher air temperature due to stagnant winds was observed in the northwest area of Metro Manila. High heat index was also observed throughout Metro Manila from daytime until nighttime, especially in areas near bodies of water like Manila Bay and Laguna Lake due to high humidity.

Probabilistic projections of increased heat stress driven by climate change

The Heat Index is a metric that quantifies heat exposure in human beings. Here, using probabilistic emission projections, we show that changes in the Heat Index driven by anthropogenic CO2 emissions will increase global exposure to dangerous environments in the coming decades. Even if the Paris Agreement goal of limiting global warming to 2 °C is met, the exposure to dangerous Heat Index levels will likely increase by 50–100% across much of the tropics and increase by a factor of 3–10 in many regions throughout the midlatitudes. Without emissions reductions more aggressive than those considered possible by our statistical projection, it is likely that by 2100, many people living in tropical regions will be exposed to dangerously high Heat Index values during most days of each typical year, and that the kinds of deadly heat waves that have been rarities in the midlatitudes will become annual occurrences.

Effects of GnRH and hCG administration during early luteal phase on estrous cycle length, expression of estrus and fertility in lactating dairy cows

Our objective was to determine the effects of a single treatment of human chorionic gonadotropin (hCG) or GnRH from d 5 to 7 of the estrous cycle on cycle length, expression of estrus and fertility in lactating dairy cows. Lactating Holstein cows (n = 354) located in Farm 1 and lactating Jersey cows located in Farm 2 (n = 210) detected in estrus by an Automated Activity Monitor (AAM) system from 27 to 50 days in milk (DIM) were randomly assigned to receive one of three treatments from d 5 to 7 of the estrous cycle: control (untreated; CON; Holstein, n = 111; Jersey, n = 66), GnRH (86 μg gonadorelin acetate im; Holstein, n = 116; Jersey, n = 75), or hCG (3,300 IU im; Holstein, n = 127; Jersey, n = 69). Ovaries were scanned with ultrasound in a random subgroup of cows (Holstein/Farm 1, n = 147; Jersey/Farm 2, n = 94) on the day of treatment and 3 or 4 d later to determine ovulation. Estrus was detected after treatment by an AAM, and peak activity and heat index were recorded. A random subgroup of cows observed in estrus after treatment received first AI from 51 to 80 DIM (Holstein, n = 208; Jersey, n = 138). Pregnancy diagnoses were performed by transrectal ultrasonography at 37 ± 3 d post-AI. Holstein and Jersey cows treated with GnRH and hCG had an increased (P < 0.05) ovulatory response compared with controls. Human chorionic gonadotropin decreased (74%; P = 0.05) and GnRH tended to reduce (75%; P = 0.07) the proportion of multiparous Holstein cows returning to estrus compared with CON (86%). Cows treated with hCG had a longer (P < 0.01) estrous cycle length (24.6 ± 0.3 d, Holstein; 23.0 ± 0.3 d, Jersey) compared with CON cows (22.7 ± 0.3 d, Holstein; 21.3 ± 0.3 d Jersey) and GnRH (22.9 ± 0.3 d, Holstein; 21.1 ± 0.3 d Jersey). The percentage of cows with high (≥80) peak activity and heat index did not differ (P > 0.50) between treatments, and milk production did not affect (P > 0.65) the duration of estrus. Pregnancy per AI (P/AI) was not affected by treatments in Holstein (P = 0.93; CON: 34.3%, GnRH: 35.4%, and hCG: 31.5%) and in multiparous Jersey cows (P = 0.35; CON: 34.3%, GnRH: 35.4%, and hCG: 31.5%), but hCG had greater (P = 0.03; 55%) P/AI than GnRH (30.0%) and a trend (P = 0.06) for greater P/AI than CON (33.3%) in primiparous Jersey cows. In summary, inducing the formation of an accessory corpus luteum from d 5 to 7 of the estrous cycle with hCG reduced expression of estrus in multiparous Holstein cows. Moreover, hCG increased estrous cycle length in Holstein and Jersey cows, and it did not affect first service P/AI at 37 ± 3 d post-AI in Holstein and multiparous Jersey lactating cows. However, hCG increased P/AI in primiparous Jersey cows. Future research with a larger number of cows is needed to confirm these intriguing fertility results.

Do weather parameters affect emergency room visits due to acute urinary retention?

Objective: This study aimed to describe the effects of the various climate parameters on emergency room (ER) visits due to acute urinary retention (AUR). Patients and methods: This was a single-center retrospective analysis of the ER data of visits due to AUR in males and females between 2010 and 2017. We incorporated ER registries with data from the national meteorological service. Using multivariable logistic regression analyses, we assessed associations between climate parameters and the incidence of AUR. Results: A total of 1917 patients were admitted to the ER due to AUR during the study period, of whom 1706 (89%) were males and211 (11%) were females. Most AURs occurred in patients &gt;70 years of age, with males on average being older than women (72.8 vs. 70.1 years old, p=0.01). Multivariable logistic regression analyses demonstrated that females had more AURs than men (odds ratio (OR)=1.3, 95% confidence interval (CI) 1.1–1.9, p=0.04) in spring. In all seasons except winter, a higher maximal temperature was associated with an increased risk of AUR, while in winter, a lower temperature was associated with an increased risk (OR=0.654, 95% CI 0.602–0.711, p&lt;0.0001). Additionally, the following were associated with an increased AUR risk: increased wind speed and lower heat index during the spring, increased precipitation and a lower heat index during the autumn, and a higher heat index in the winter. Conclusions: Our data suggest that weather parameters might be associated with an increased AUR incidence in a Mediterranean coastline area, with maximal ambient temperature, wind speed, heat index, and precipitation playing a potential role. Level of evidence: 6.

Impact of Extreme Weather on Healthcare Utilization by People with HIV in Metropolitan Miami.

Extreme weather events (EWE) are expected to increase as climate change intensifies, leaving coastal regions exposed to higher risks. South Florida has the highest HIV infection rate in the United States, and disruptions in clinic utilization due to extreme weather conditions could affect adherence to treatment and increase community transmission. The objective of this study was to identify the association between EWE and HIV-clinic attendance rates at a large academic medical system serving the Miami-Dade communities. The following methods were utilized: (1) Extreme heat index (EHI) and extreme precipitation (EP) were identified using daily observations from 1990–2019 that were collected at the Miami International Airport weather station located 3.6 miles from the studied HIV clinics. Data on hurricanes, coastal storms and flooding were collected from the National Oceanic and Atmospheric Administration Storms Database (NOAA) for Miami-Dade County. (2) An all-HIV clinic registry identified scheduled daily visits during the study period (hurricane seasons from 2017–2019). (3) Daily weather data were linked to the all-HIV clinic registry, where patients’ ‘no-show’ status was the variable of interest. (4) A time-stratified, case crossover model was used to estimate the relative risk of no-show on days with a high heat index, precipitation, and/or an extreme natural event. A total of 26,444 scheduled visits were analyzed during the 383-day study period. A steady increase in the relative risk of ‘no-show’ was observed in successive categories, with a 14% increase observed on days when the heat index was extreme compared to days with a relatively low EHI, 13% on days with EP compared to days with no EP, and 10% higher on days with a reported extreme weather event compared to days without such incident. This study represents a novel approach to improving local understanding of the impacts of EWE on the HIV-population’s utilization of healthcare, particularly when the frequency and intensity of EWE is expected to increase and disproportionately affect vulnerable populations. More studies are needed to understand the impact of EWE on routine outpatient settings.

Characterization of heat index experienced by individuals residing in urban and rural settings.

Heatwave warning systems rely on forecasts made for fixed-point weather stations (WS), which do not reflect variation in temperature and humidity experienced by individuals moving through indoor and outdoor locations. We examined whether neighborhood measurement improved the prediction of individually experienced heat index in addition to nearest WS in an urban and rural location. Participants (residents of Birmingham, Alabama [N=89] and Wilcox County, Alabama [N=88]) wore thermometers clipped to their shoe for 7 days. Shielded thermometers/hygrometers were placed outdoors within participant’s neighborhoods (N=43). Nearest WS and neighborhood thermometers were matched to participant’s home address. Heat index (HI) was estimated from participant thermometer temperature and WS humidity per person-hour (HI[individual]), or WS temperature and humidity, or neighborhood temperature and humidity. We found that neighborhood HI improved the prediction of individually experienced HI in addition to WS HI in the rural location, and neighborhood heat index alone served as a better predictor in the urban location, after accounting for individual-level factors. Overall, a 1°C increase in HI[neighborhood] was associated with 0.20°C [95%CI (0.19, 0.21)] increase in HI[individual]. After adjusting for ambient condition differences, we found higher HI[individual] in the rural location, and increased HI[individual] during non-rest time (5am-midnight) and on weekdays.

A modified physiological strain index for workplace-based assessment of heat strain experienced by agricultural workers.

As global temperatures rise, increasing numbers of individuals will work in hot environments. Interventions to protect their health are critical, as are reliable methods to measure the physiological strain experienced from heat exposure. The physiological strain index (PSI) is a measure of heat strain that relies on heart rate and core temperature but is challenging to calculate in a real-world occupational setting. We modified the PSI for use in field settings where resting temperature and heart rate are not available and used the modified physiological strain index (mPSI) to describe risk factors for high heat strain (mPSI ≥ 7) experienced by agricultural workers in Florida during the summers of 2015 through 2017. mPSI was calculated for 221 workers, yielding 465 days of data. A higher heat index (β = 0.185; 95% CI: 0.064, 0.307) and higher levels of physical activity at work (0.033; 95% CI: 0.017, 0.050) were associated with a higher maximum mPSI. More years worked in US agriculture (-0.041; 95% CI: -0.061, -0.020) were protective against a higher maximum mPSI. Out of 23 workdays that a participant experienced a maximum mPSI ≥ 7, 22 were also classified as strained by at least one other measure of high heat strain (core temperature [Tc] >38.5°C, sustained heart rate>(180 - age), and mean heart rate > 115 bpm). This study provides critical information on risk factors for elevated heat strain for agricultural workers and suggests a practical approach for using PSI in field-based settings.

Birthweight and Environmental Conditions Impact Skin Barrier Adaptation in Neonates Receiving Natural Oil Massage

Introduction: Skin interventions have been implemented to reduce neonatal mortality, demonstrating the skin’s role in neonatal innate immunity. We examined the impact of birthweight and environmental conditions on skin integrity in infants receiving oil massage in rural Nepal. Methods: In a community-based cluster randomized controlled trial, 991 premature and full-term infants were grouped by birthweight as: (1) 920–1,560 g, (2) 1,570–2,450 g, (3) 2,460–2,990 g, and (4) 3,000–4,050 g and by high or low heat index (HI). Skin integrity was measured as erythema, rash, dryness, pH, protein concentration, and transepidermal water loss (TEWL). Results: Skin pH was higher for the smallest (group 1) than the largest infants (group 4) and higher for group 2 than 3 and 4. Arm and leg rash differed for all 4 groups, with the least amount of rash for the smallest babies. Erythema was lower for group 1 than all others. The lower day 1 values for pH, TEWL and protein at high versus low HI remained lower over 28 days. The pH reduction was faster at high HI. Erythema (arm, leg) was more severe at high HI. Rash severity was greater at high HI for arms and legs every day. Conclusions: Birthweight influenced the skin response to oil massage. The smallest infants had the lowermost skin irritation, suggesting diminished ability to mount an inflammatory response. High HI may be protective for premature infants in low resource settings.

Effects of Apparent Temperature on the Incidence of Ventricular Tachyarrhythmias in Patients With an Implantable Cardioverter-Defibrillator: Differential Association Between Patients With and Without Electrical Storm.

Background: Electrical storm (ES) has profound psychological effects and is associated with a higher mortality in patients with implantable cardioverter–defibrillator (ICD). Assessing the incidence and features of ES, is vital. Previous studies have shown winter peaks for ventricular tachyarrhythmia (VTA) in ICD patients. However, the effects of heat with a high relative humidity remain unclear. Thus, this study aimed to assess the nonlinear and lagged effects of apparent temperature [or heat index (HI)] on VTA among patients with and without ES after ICD implantation.Methods: Of 626 consecutive patients who had ICDs implanted from January 2004 to June 2017 at our hospital, 172 who experienced sustained VTAs in ICD recording were analyzed, and their clinical records were abstracted to assess the association between VTA incidence and HI by time-stratified case-crossover analysis. Cubic splines were used for the nonlinear effect of HI, with adjustment for air pollutant concentrations.Results: A significant seasonal effect for ES patients was noted. Apparent temperature, but not ambient temperature, was associated with VTA occurrences. The low and high HI thresholds for VTA incidence were <15° and >30°C, respectively, with a percentage change in odds ratios of 1.06 and 0.37, respectively, per 1°C. Lagged effects could only be demonstrated in ES patients, which lasted longer for low HI (in the next 4 days) than high HI (in the next 1 day).Conclusion: VTA occurrence in ICD patients was strongly associated with low HI and moderately associated with high HI. Lagged effects of HI on VTA were noted in patients with ES. Furthermore, patients with ES were more vulnerable to heat stress than those without ES. Patients with ICD implantation, particularly in those with ES, should avoid exposure to low and high HI to reduce the risk of VTAs, improve quality of life and possibly reduce mortality.

Effects of trees, gardens, and nature trails on heat index and child health: design and methods of the Green Schoolyards Project

BackgroundLatinx children in the United States are at high risk for nature-deficit disorder, heat-related illness, and physical inactivity. We developed the Green Schoolyards Project to investigate how green features—trees, gardens, and nature trails—in school parks impact heat index (i.e., air temperature and relative humidity) within parks, and physical activity levels and socioemotional well-being of these children. Herein, we present novel methods for a) observing children’s interaction with green features and b) measuring heat index and children’s behaviors in a natural setting, and a selection of baseline results.MethodsDuring two September weeks (high temperature) and one November week (moderate temperature) in 2019, we examined three joint-use elementary school parks in Central Texas, United States, serving predominantly low-income Latinx families. To develop thermal profiles for each park, we installed 10 air temperature/relative humidity sensors per park, selecting sites based on land cover, land use, and even spatial coverage. We measured green features within a geographic information system. In a cross-sectional study, we used an adapted version of System for Observing Play and Recreation in Communities (SOPARC) to assess children’s physical activity levels and interactions with green features. In a cohort study, we equipped 30 3rd and 30 4th grade students per school during recess with accelerometers and Global Positioning System devices, and surveyed these students regarding their connection to nature. Baseline analyses included inverse distance weighting for thermal profiles and summing observed counts of children interacting with trees.ResultsIn September 2019, average daily heat index ranged 2.0 °F among park sites, and maximum daily heat index ranged from 103.4 °F (air temperature = 33.8 °C; relative humidity = 55.2%) under tree canopy to 114.1 °F (air temperature = 37.9 °C; relative humidity = 45.2%) on an unshaded playground. 10.8% more girls and 25.4% more boys interacted with trees in September than in November.ConclusionsWe found extreme heat conditions at select sites within parks, and children positioning themselves under trees during periods of high heat index. These methods can be used by public health researchers and practitioners to inform the redesign of greenspaces in the face of climate change and health inequities.

Effects of weather factors on recreation participation in a humid subtropical region.

This study examines effects of weather, temporal factors, and gasoline price on outdoor recreation participation by using a time series model. We obtained more than 5years of daily outdoor recreation visitation data by using infrared mechanical counters on a section of the Florida National Scenic Trail (FNST). Results showed that days with daily maximum temperatures of 16-22°C brought the largest number of visitors, which suggests this is the most comfortable range of daily maximum temperatures to recreate on the FNST. Daily maximum temperatures below 6°C and above 31°C and heat index values above 38°C brought significantly lower visitor numbers, suggesting these values are temperature thresholds for this region in a recreation context. A seasonal autoregressive integrated moving average model showed significant negative effects of temperature, relative humidity, cold snaps, and gasoline price and a positive effect of weekends and public holidays on recreational visitations to this trail. Days with heavy rainfall (> 2.54cm) or a high heat index (≥ 35°C) were likely to negatively affect recreation participation not only on the same day, but also on the next normal weather day. These findings imply that managers of facilities that need staffing and other resources should expect to receive fewer visitors on days following adverse weather conditions, even if that day has normal weather conditions.

A better indicator to measure the effects of meteorological factors on cardiovascular mortality: heat index.

Although many studies have examined the correlation between temperature and mortality from cardiovascular diseases (CVD), other meteorological factors, such as relative humidity, may modify the relationship. Yet the studies on this aspect are relatively few. We chose a heat index (HI, which is an index that combines air temperature and relative humidity) as an alternative indicator of temperature, and used a distributed lag nonlinear model (DLNM) to analyze the combined effects of temperature and relative humidity on CVD mortality among all of the Beijing residents and subsociodemographic groups by age, sex, and occupation. The heat index can better reflect the human-perceived temperature when relative humidity is combined with air temperature. The results show that females, elderly people, and outdoor workers have higher vulnerability levels in regard to a high heat index. The strongest effect of heat index was found among females, for which the highest mortality risk was about 2.4 (95% CI 1.8-3) times greater than the lowest mortality risk. In addition, we found that there is a significant interaction effect of temperature and relative humidity on CVD mortality. The impact of extreme high temperature may be exacerbated by increases in humidity. Based on these results, we draw the risk level map of CVD death under different temperatures and grades of relative humidity. These findings may aid governments in the development of more accurate heat alerts and the provision of measures to prevent or reduce temperature-related deaths.