Maximum Heat Index Research Articles

Spatial patterns of recent US summertime heat trends: Implications for heat sensitivity and health adaptations

Heat is known to cause illness and death not only at extreme temperatures, but also at moderate levels. Although substantial research has shown how summertime temperature distributions have changed over recent decades in the United States, less is known about how the heat index—a potentially more health-applicable metric of heat—has similarly evolved over this period. Moreover, the extent to which these distributional changes have overlapped with indicators of social vulnerability has not been established, despite the applicability of co-varying climatic and sociodemographic characteristics to heat-related health adaptations. Presented here is an analysis of trends in the median, 95th percentile, and ‘warm-tail spread’ (i.e., intra-seasonal range between the upper extreme and median) of warm-season (May-September) maximum heat index between 1979 and 2018 across the conterminous US. Using 40 years of data from the North American Regional Reanalysis dataset, it is shown that most of the US has experienced statistically significant positive trends in summertime heat, and that both the magnitude of trends and the shape of the frequency distributions of these measures vary regionally. Comparisons with data from the Social Vulnerability Index show that the most socially vulnerable counties appear to be warming faster than the least vulnerable, but that opposite patterns hold for trends in warm-tail spread. These findings may be applicable to further studies on climate change, heat adaptations, and environmental justice in the US.

Physical Activity in the Summer Heat: How Hot Weather Moderates the Relationship Between Built Environment Features and Outdoor Physical Activity of Adults.

Research has not yet examined how hot weather moderates the relationship between the built environment and outdoor physical activity levels. The authors posited that hot days will increase the magnitude of the expected directional effect of built environment features on physical activity. This longitudinal study included 134 US adults from the Three city Heat and Electrical failure AdapTation study. Adults self-reported physical activity for multiple summer days (nstudy-days = 742) in 2016. Hot days were defined as ≥90th percentile of daily maximum heat index. Built environment features included density, safety, trees, hilliness, connectivity, access to parks, and access to shops + services. Separate growth curve models with interaction terms (ie,hot day × built environment feature) were run for daily minutes of outdoor physical activity (ie,any activity and recommended activity). Neither hot days nor built environment features impacted outdoor physical activity significantly, and hot days did not moderate the relationship between built environment features and physical activity (P > .05). With adults failing to modify behavior on hot days, cities may be placing adults at increased risk of exertional heat illness. The authors recommend incorporating the risk of exertional heat illness in health impact assessments and deploying heat management strategies.

Changes in the frequency of hot, humid days and nights in the Mississippi River Basin

AbstractThe severe impacts of climate change on human health will rise from the co‐occurrence of extreme humid and hot conditions. In this study, six indices associated with high humidity, maximum and minimum daytime and nighttime temperature and the heat index (HI) values were analysed to assess temporal changes in hot, humid conditions in the Mississippi River Basin (MRB), USA, for the period 1948–2017. The frequencies of extreme humid days and nights have significant upward trends over 97 and 93% of MRB, respectively. Trends of day‐time HI were mainly upward (63%), except for eastern regions of MRB. More of the upward trends for the frequency of hot nights were significant than the trends for hot days either for the entire period (72% of MRB for hot nights and 4% for hot days) or after a significant change‐point (26% of MRB for hot nights and 20% for hot days). Except for minimum HI, other indices including extreme maximum and minimum temperature and specific humidity as well as maximum HI had an upward trend after the 1980s and 1990s for the majority of grid‐cells. Central and southern areas of the MRB were identified as regions most at risk for an extreme HI value during both days and nights.

Estimating policy-relevant health effects of ambient heat exposures using spatially contiguous reanalysis data

BackgroundRegional National Weather Service (NWS) heat advisory criteria in New York State (NYS) were based on frequency of heat events estimated by sparse monitoring data. These may not accurately reflect temperatures at which specific health risks occur in large geographic regions. The objectives of the study were to use spatially resolved temperature data to characterize health risks related to summertime heat exposure and estimate the temperatures at which excessive risk of heat-related adverse health occurs in NYS. We also evaluated the need to adjust current heat advisory threshold and messaging based on threshold temperatures of multiple health outcomes.MethodsWe assessed the effect of multi-day lag exposure for maximum near-surface air temperature (Tmax) and maximum Heat Index derived from the gridded National Land Data Assimilation System (NLDAS) reanalysis dataset on emergency department (ED) visits/ hospitalizations for heat stress, dehydration, acute kidney failure (AKF) and cardiovascular diseases (CVD) using a case-crossover analysis during summers of 2008–2012. We assessed effect modification using interaction terms and stratified analysis. Thresholds were estimated using piecewise spline regression.ResultsWe observed an increased risk of heat stress (Risk ratio (RR) = 1.366, 95% confidence interval (CI): 1.347, 1.386) and dehydration (RR = 1.024, 95% CI: 1.021, 1.028) for every 1 °C increase in Tmax on the day of exposure. The highest risk for AKF (RR = 1.017, 95% CI: 1.014, 1.021) and CVD (RR = 1.001, 95% CI: 1.000, 1.002) were at lag 1 and 4 respectively. The increased risk of heat-health effects persists up to 6 days. Rural areas of NYS are at as high a risk of heat-health effects as urban areas. Heat-health risks start increasing at temperatures much lower than the current NWS criteria.ConclusionReanalysis data provide refined exposure-response functions for health research, in areas with sparse monitor observations. Based on this research, rural areas in NYS had similar risk for health effects of heat. Heat advisories in New York City (NYC) had been reviewed and lowered previously. As such, the current NWS heat advisory threshold was lowered for the upstate region of New York and surrounding areas. Enhanced outreach materials were also developed and disseminated to local health departments and the public.

Actual and simulated weather data to evaluate wet bulb globe temperature and heat index as alerts for occupational heat-related illness

Heat stress occupational exposure limits (OELs) were developed in the 1970s to prevent heat-related illnesses (HRIs). The OELs define the maximum safe wet bulb globe temperature (WBGT) for a given physical activity level. This study’s objectives were to compute the sensitivity of heat stress OELs and determine if Heat Index could be a surrogate for WBGT. We performed a retrospective analysis of 234 outdoor work-related HRIs reported to the Occupational Safety and Health Administration in 2016. Archived NOAA weather data were used to compute each day’s maximum WBGT and Heat Index. We defined the OELs’ sensitivity as the percentage of incidents with WBGT > OEL. Sensitivity of the OELs was between 88% and 97%, depending upon our assumption about acclimatization status. In fatal cases, the OELs’ sensitivity was somewhat higher (92–100%). We also computed the sensitivity of each possible Heat Index discrimination threshold. A Heat Index threshold of 80 °F (26.7 °C) was exceeded in 100% of fatalities and 99% of non-fatal HRIs. In a separate analysis, we created simulated weather data to assess associations of WBGT with Heat Index over a range of realistic outdoor heat conditions. These simulations demonstrated that for a given Heat Index, when radiant heat was included, WBGT was often higher than previously reported. The imperfect correlation between WBGT and Heat Index precluded a direct translation of OELs from WBGT into Heat Index. We conclude that WBGT-based heat stress exposure limits are highly sensitive and should be used for workplace heat hazard assessment. When WBGT is unavailable, a Heat Index alert threshold of approximately 80 °F (26.7 °C) could identify potentially hazardous workplace environmental heat.

Contiguous US summer maximum temperature and heat stress trends in CRU and NOAA Climate Division data plus comparisons to reanalyses

Warming is a major climate change concern, but the impact of high maximum temperatures depends upon the air’s moisture content. Trends in maximum summertime temperature, moisture, and heat index are tracked over three time periods: 1900–2011, 1950–2011, and 1979–2011; these trends differ notably from annual temperature trends. Trends are emphasized from two CRU datasets (CRUTS3.25 and CRUTS4.01) and two reanalyses (ERA-20C and 20CRv2). Maximum temperature trends tend towards warming that is stronger over the Great Lakes, the interior western and the northeastern contiguous United States. A warming hole in the Midwest generally decreases in size and magnitude when heat stress trends are calculated because the region has increasing moisture. CRU and nearly all reanalyses find cooling in the northern high plains that is not found in NOAA Climate Division trends. These NOAA trends are captured better by CRUTS401. Moistening in the northeast amplifies the heat stress there. Elsewhere the moisture trends are less clear. Drying over northern Texas (after 1996) in CRUTS401 translates into decreasing heat stress there (less so in CRUTS325). Though other reanalyses are not intended for long-term trends, MERRA-2 and ERA-Interim match observed trends better than other reanalyses.

Threshold Evaluation of Emergency Risk Communication for Health Risks Related to Hazardous Ambient Temperature.

Emergency risk communication (ERC) programs that activate when the ambient temperature is expected to cross certain extreme thresholds are widely used to manage relevant public health risks. In practice, however, the effectiveness of these thresholds has rarely been examined. The goal of this study is to test if the activation criteria based on extreme temperature thresholds, both cold and heat, capture elevated health risks for all-cause and cause-specific mortality and morbidity in the Minneapolis-St. Paul Metropolitan Area. A distributed lag nonlinear model (DLNM) combined with a quasi-Poisson generalized linear model is used to derive the exposure-response functions between daily maximum heat index and mortality (1998-2014) and morbidity (emergency department visits; 2007-2014). Specific causes considered include cardiovascular, respiratory, renal diseases, and diabetes. Six extreme temperature thresholds, corresponding to 1st-3rd and 97th-99th percentiles of local exposure history, are examined. All six extreme temperature thresholds capture significantly increased relative risks for all-cause mortality and morbidity. However, the cause-specific analyses reveal heterogeneity. Extreme cold thresholds capture increased mortality and morbidity risks for cardiovascular and respiratory diseases and extreme heat thresholds for renal disease. Percentile-based extreme temperature thresholds are appropriate for initiating ERC targeting the general population. Tailoring ERC by specific causes may protect some but not all individuals with health conditions exacerbated by hazardous ambient temperature exposure.

Reconnoitering the linkage between cardiovascular disease mortality and long-term exposures to outdoor environmental factors in the USA using remotely-sensed data

ABSTRACTThis ecological study aimed to assess the association between long-term exposures to outdoor environmental factors and mortality rate from cardiovascular disease (CVD) in a diverse and spatially distributed population from 3,094 counties within the U.S. (n > 3,780,000 CVD deaths) using satellite-derived data of PM2.5 concentrations, sunlight, and maximum heat index. Multivariable logistic regression analyses were conducted to determine whether PM2.5, sunlight and maximum heat index were related to the odds of the total CVD death rate based on gender, race, and age taking into consideration the confounding risk factors of diabetes, obesity, leisure- time physical inactivity, smoking and socioeconomic status. The study has shown that elevated levels of PM2.5, sunlight and heat long-term exposures are significantly associated with an increase in the odds ratio of the total CVD mortality. The results suggest a 9.8% (95% CI = 6.3% – 13.4%), 0.9% (95% CI = 0.5% – 1.2%), and 0.7% (95% CI = 0.5% – 11.2%) increase in total CVD mortality associated with 10 μg/m3 increase in PM2.5 concentrations, 1,000 kJ/m2 increases in sunlight, and 1 oF increase in heat index, respectively. The odds ratios for the CVD death rate due to long-term exposures of PM2.5, sunlight, and heat index were significantly greater than 1.0 for all categories except for Asians, Hispanics, and American Indians, indicating that the effect of long-term exposures to particulate matter, sunlight radiation, and maximum heat on CVD mortality is trivial for Asians, Hispanics, and American Indians. Among the categories of age, the group of 65 years and older had the highest odds ratios, suggesting that the age group of 65 years and older are the most vulnerable group to the environmental exposures of PM2.5 (OR = 1.179, 95% CI = 1.124 – 1.237), sunlight (OR = 1.047, 95% CI = 1.041 – 1.053), and maximum heat (OR = 1.014, 95% CI = 1.011 – 1.016). The odds ratios of CVD mortality due to the environmental exposures were higher for Blacks than those for Whites. The odds ratios for all categories were attenuated with the inclusion of diabetes, obesity, leisure-time physical inactivity, smoking, and income covariates, reflecting the effect of other medical conditions, lifestyle, behavioral and socioeconomic factors on the CVD death rate besides the environmental factors.

Investigating the effects of environmental factors on autism spectrum disorder in the USA using remotely sensed data.

This study aimed to assess the association between exposures to outdoor environmental factors and autism spectrum disorder (ASD) prevalence in a diverse and spatially distributed population of 8-year-old children from the USA (n = 2,097,188) using the air quality index (AQI) of the US Environmental Protection Agency as well as satellite-derived data of PM2.5 concentrations, sunlight, and maximum heat index. Multivariable logistic regression analyses were performed to determine whether the unhealthy AQI, PM2.5, sunlight, and maximum heat index were related to the odds of ASD prevalence based on gender and race and taking into consideration the confounding factors of smoking and socioeconomic status. The logistic regression odds ratios for ASD per 10% increase in the unhealthy AQI were greater than 1 for all categories, indicating that unhealthy AQI is related to the odds of ASD prevalence. The odds ratio of ASD due to the exposure to the unhealthy AQI was higher for Asians (OR = 2.96, 95% CI = 1.11-7.88) than that for Hispanics (OR = 1.308, 95% CI = 0.607-2.820), and it was higher for Blacks (OR = 1.398, 95% CI = 0.827-2.364) than that for Whites (OR = 1.219, 95% CI = 0.760-1.954). The odds ratio of ASD due to the unhealthy AQI was slightly higher for males (OR = 1.123, 95% CI = 0.771-1.635) than that for females (OR = 1.117, 95% CI = 0.789-1.581). The effects of the unhealthy environmental exposures on the odds ratios of ASD of this study were inconclusive (i.e., statically insignificant; p value > 0.05) for all categories except for Asians. The odds ratios of ASD for Asians were increased by 5, 12, and 14% with increased levels of the environmental exposures of 10μg/m3 of PM2.5, 1000kJ/m2 of sunlight, and 1°F of maximum heat index, respectively. The odds ratios of ASD prevalence for all categories, except for Asians, were increased with the inclusion of the smoking covariate, reflecting the effect of smoking on ASD prevalence besides the unhealthy environmental factors.

Analysis of the Heat Index in the Mesoamerica and Caribbean Region

AbstractHourly data collected from ground stations were used to study the maximum daytime heat index Hi in the Mesoamerica and Caribbean Sea (MAC) region for a 35-yr period (1980–2014). Observations of Hi revealed larger values during the rainy season and smaller values during the dry season. The Hi climatology exhibits the largest values in Mesoamerica, followed by the Greater Antilles and then by the Lesser Antilles. The trend in Hi indicates a notable increasing pattern of 0.05°C yr−1 (0.10°F yr−1), and the trends are more prominent in Mesoamerica than in Caribbean countries. This work also includes the analysis of heat index extreme events (HIEE). Usually the extreme values of the heat index are used for advising heat warning events, and it was found that 45 HIEEs occurred during the studied period. The average duration of HIEE was 2.4 days, and the average relative intensity (excess over the threshold) was 2.4°C (4.3°F). It was found that 82% of HIEE lasted 2 or 2.5 days and 80% exhibited relative intensity of 3°C (5.4°F) or less. It was also found that the frequency of extreme events has intensified since 1991, with the highest incidences occurring in 1995, 1998, 2005 and 2010, and these years coincide with the cool phase of El Niño–Southern Oscillation (ENSO). Therefore, the occurrences of HIEE in the MAC region appear to be at least partially influenced by ENSO episodes.

Heat-related morbidity and mortality in New England: Evidence for local policy

BackgroundHeat-related morbidity and mortality is a recognized public health concern. However, public health officials need to base policy decisions on local evidence, which is often lacking for smaller communities. ObjectivesTo evaluate the association between maximum daily heat index (HI) and morbidity and mortality in 15 New England communities (combined population: 2.7 million) in order to provide actionable evidence for local officials. MethodsWe applied overdispersed Poisson nonlinear distributed lag models to evaluate the association between HI and daily (May-September) emergency department (ED) admissions and deaths in each of 15 study sites in New Hampshire, Maine, and Rhode Island, controlling for time trends, day of week, and federal holidays. Site-specific estimates were meta-analyzed to provide regional estimates. ResultsAssociations (sometimes non-linear) were observed between HI and each health outcome. For example, a day with a HI of 95°F vs. 75°F was associated with a cumulative 7.5% (95% confidence interval [CI]: 6.5%, 8.5%) and 5.1% (95% CI: 0.2%, 10.3%) higher rate of all-cause ED visits and deaths, respectively, with some evidence of regional heterogeneity. We estimate that in the study area, days with a HI≥95°F were associated with an annual average of 784 (95% CI: 658, 908) excess ED visits and 22 (95% CI: 3, 39) excess deaths. ConclusionsOur results suggest the presence of adverse health impacts associated with HI below the current local guideline criteria of HI≥100°F used to issue heat advisories. We hypothesize that lowering this threshold may lead to substantially reduced heat-related morbidity and mortality in the study area.

Effect of Missing Data on Estimation of the Impact of Heat Waves: Methodological Concerns for Public Health Practice

(1) Background: To demonstrate the potential effects of missing exposure data and model choice on public health conclusions concerning the impact of heat waves on heat-related morbidity. (2) Methods: Using four different methods to impute missing exposure data, four statistical models (case-crossover, time-series, zero-inflated, and truncated models) are compared. The methods are used to relate heat waves, based on heat index, and heat-related morbidities for Florida from 2005–2012. (3) Results: Truncated models using maximum daily heat index, imputed using spatio-temporal methods, provided the best model fit of regional and statewide heat-related morbidity, outperforming the commonly used case-crossover and time-series analysis methods. (4) Conclusions: The extent of missing exposure data, the method used to impute missing exposure data and the statistical model chosen can influence statistical inference. Further, using a statewide truncated negative binomial model, statistically significant associations between heat-related morbidity and regional heat index effects were identified.

Summer Temperature and Spatial Variability of all-Cause Mortality in Surat City, India.

Background:Ample information is available on extreme heat associated mortality for few Indian cities, but scant literature is available on effect of temperature on spatial variability of all-cause mortality for coastal cities.Objective:To assess the effect of daily maximum temperature, relative humidity and heat index on spatial variability of all-cause mortality for summer months (March to May) from 2014 to 2015 for the urban population of Surat (coastal) city.Materials and Methods:Retrospective analysis of the all-cause mortality data with temperature and humidity was performed on a total of 9,237 deaths for 184 summer days (2014-2015). Climatic and all-cause mortality data were obtained through Tutiempo website and Surat Municipal Corporation respectively. Bivariate analysis performed through SPSS.Observations:Mean daily mortality was estimated at 50.2 ± 8.5 for the study period with a rise of 20% all-cause mortality at temperature ≥ 40°C and rise of 10% deaths per day during extreme danger level (HI: > 54°C) days. Spatial (Zone wise) analysis revealed rise of 61% all-cause mortality for Southeast and 30% for East zones at temperature ≥ 40°C.Conclusions:All-cause mortality increased on high summer temperature days. Presence of spatial variation in all-cause mortality provided the evidence for high risk zones. Findings may be helpful in designing the interventions at micro level.

Spatiotemporal analysis of heat and heat wave effects on elderly mortality in Texas, 2006–2011

BackgroundHeat and heat waves have been linked to the increased risk of deaths, hospital admissions, and emergency visits. ObjectivesThis study presents a spatiotemporal analysis of heat and heat wave effects on elderly mortality (≥65years) in Texas. MethodsWe compiled a six-year daily weather and mortality counts dataset from 254 counties in Texas during 2006–2011. Heat index (HI), a combination of temperature and relative humidity, was used as the exposure metric in this study. Associations between daily all-cause elderly mortality and daily maximum HI and heat waves (≥2days of county-specific daily maximum HI>95th percentiles) were examined using a quasi-Poisson regression. A Markov random field smoother was included in the model to account for spatial autocorrelations and spatial heterogeneity. The model also controlled for long-term trend and seasonality in mortality, and the effects of day of the week. DiscussionOn average, the lag effect of heat on elderly mortality risk lasted up to 10days, and the cumulative heat effects started to increase rapidly when daily maximum HI exceeded the 90th percentile in Texas. Elderly living in Northwest Texas and parts of West Texas were at greater risk of elderly mortality attributable to heat waves, and the highest relative risk for elderly mortality occurred in El Paso County (4.70, 95% Confidence Interval=4.33, 5.10). ConclusionsOur study indicates strong geographical variations of heat wave effects on elderly mortality risk in Texas.

Potential Impacts of Future Warming and Land Use Changes on Intra-Urban Heat Exposure in Houston, Texas.

Extreme heat events in the United States are projected to become more frequent and intense as a result of climate change. We investigated the individual and combined effects of land use and warming on the spatial and temporal distribution of daily minimum temperature (Tmin) and daily maximum heat index (HImax) during summer in Houston, Texas. Present-day (2010) and near-future (2040) parcel-level land use scenarios were embedded within 1-km resolution land surface model (LSM) simulations. For each land use scenario, LSM simulations were conducted for climatic scenarios representative of both the present-day and near-future periods. LSM simulations assuming present-day climate but 2040 land use patterns led to spatially heterogeneous temperature changes characterized by warmer conditions over most areas, with summer average increases of up to 1.5°C (Tmin) and 7.3°C (HImax) in some newly developed suburban areas compared to simulations using 2010 land use patterns. LSM simulations assuming present-day land use but a 1°C temperature increase above the urban canopy (consistent with warming projections for 2040) yielded more spatially homogeneous metropolitan-wide average increases of about 1°C (Tmin) and 2.5°C (HImax), respectively. LSM simulations assuming both land use and warming for 2040 led to summer average increases of up to 2.5°C (Tmin) and 8.3°C (HImax), with the largest increases in areas projected to be converted to residential, industrial and mixed-use types. Our results suggest that urbanization and climate change may significantly increase the average number of summer days that exceed current threshold temperatures for initiating a heat advisory for metropolitan Houston, potentially increasing population exposure to extreme heat.

Effect Of Land-Based Mitigation Strategies On Urban Heat Island And Health

Background Increases in extreme heat from climate change in urban environments is a health concern with an identified gap in understanding how ongoing land-based mitigation strategies affect urban heat island (UHI) and heat-related mortality/morbidity. Some major U.S. cities have started to implement vegetation and/or albedo strategies to reduce UHI, as a climate adaptation strategy. The vast extent of satellite and weather data represent a unique opportunity to examine how vegetation and albedo surface reflectance affect UHI and subsequently health. Methods We examined the relationship between climate action plans (CAPS), MODIS-derived normalized difference vegetation index (NDVI) and albedo surface reflectance with daily temperature for 11 major U.S. urban areas (Atlanta, GA; Baltimore, MD; Boston, MA; Chicago, IL; Houston, TX; Las Vegas, NV; Los Angeles, CA; Miami, FL; New York, NY; Philadelphia, PA; Phoenix, AZ) for May-September from 2000-2012. City-level albedo and vegetation were examined for temporal trends and association with maximum daily temperature and heat index, with adjustment for year, month, and region. Results Preliminary findings found that 6 of 7 cities with a vegetation CAP had a significant increase in NDVI during the study period. CAPs that increased vegetation were associated with a -5.4°C (95%CI: -5.6, -5.3) decrease in mean daily maximum temperature and a heat index -3.4°C (95%CI: -3.5, -3.2) compared to cities without a CAP. A 1% NDVI increase was associated with a -0.38°C (95%CI: -0.43, -0.34) decrease in daily maximum temperature and a -0.41 (95%CI: -0.51, -0.31) decrease in daily heat index. Albedo based CAPs and the percent albedo had similar trends, but lower effect estimates than did vegetation. Conclusion Results indicate that local daily ambient temperature conditions could be modified by vegetation and albedo levels. These changes are likely to impact health and are highly relevant to discussions of the impacts of climate change.

Intra-urban vulnerability to heat-related mortality in New York City, 1997–2006

The health impacts of exposure to summertime heat are a significant problem in New York City (NYC) and for many cities and are expected to increase with a warming climate. Most studies on heat-related mortality have examined risk factors at the municipal or regional scale and may have missed the intra-urban variation of vulnerability that might inform prevention strategies. We evaluated whether place-based characteristics (socioeconomic/demographic and health factors, as well as the built and biophysical environment) may be associated with greater risk of heat-related mortality for seniors during heat events in NYC. As a measure of relative vulnerability to heat, we used the natural cause mortality rate ratio among those aged 65 and over (MRR65+), comparing extremely hot days (maximum heat index 100°F+) to all warm season days, across 1997–2006 for NYC’s 59 Community Districts and 42 United Hospital Fund neighborhoods. Significant positive associations were found between the MRR65+ and neighborhood-level characteristics: poverty, poor housing conditions, lower rates of access to air-conditioning, impervious land cover, surface temperatures aggregated to the area-level, and seniors’ hypertension. Percent Black/African American and household poverty were strong negative predictors of seniors’ air conditioning access in multivariate regression analysis.

Tendências das séries históricas do índice de calor no município de Santa Maria - RS

Este trabalho teve como objetivo calcular e analisar as séries históricas mensais do Índice de Calor (IC) para Santa Maria, RS, Brasil, no período de 1968 a 2011. As variáveis meteorológicas utilizadas neste trabalho foram pressão atmosférica, temperatura do bulbo seco e temperatura do bulbo úmido, no horário das 9h (12UTC), 15h (18UTC) e 21h (00UTC). Foi realizada análise de tendência das séries históricas para o valor absoluto e a média mensais do IC através do teste de Mann-Kendall e análise de regressão linear simples para quantificar a tendência, com nível de significância de 95% (α=0,05). Para o valor máximo, no horário das 15h (18UTC), as séries históricas para os meses de janeiro e abril apresentaram acréscimo no valor do índice de calor na magnitude de 0,76°C década-1 e 0,92°C década-1, respectivamente. No horário das 21h (00 UTC), os meses de abril e novembro apresentaram aumento de 0,43°C década-1 e 0,55°C década-1, respectivamente. Porém os meses de maio e agosto apresentaram diminuição de 0,69°C década-1 e 0,31°C década-1, respectivamente.

The effects of temperature on heat-related illness according to characteristic of patients during the summer of 2012 in Republic of Korea

Background Damages caused by heat waves are expected to be on the rise with climate change. Accordingly, heat-related morbidity and mortality are likely to grow significantly. Nevertheless, the pattern of incidence of heat-related illnesses and its relationship with temperature have rarely been investigated. Aims This study was conducted to investigate the relationship between heat-related illnesses developed in the summer of 2012 and temperature. Methods The study analyzed data generated by a heat wave surveillance system operated by the Korea Centers for Disease Control and Prevention during the summer of 2012. The daily maximum temperature, average temperature, and maximum heat index were compared to identify the most suitable index for this study. A piecewise linear model was used to identify the threshold temperature and the relative risk (RR) above the threshold temperature according to patient characteristics and region. Results The total number of patients during the 3 months was 975. Of the three temperature indicators, the daily maximum temperature showed the best goodness of fit with the model. The RR of the total patient incidence was 1.691 (1.641 to 1.743) per 1°C after 31.2°C. The RR above the threshold temperature of women (1.822, 1.716 to 1.934) was greater than that of men (1.643, 1.587 to 1.701). The threshold temperature was the lowest in the age group of 20 to 64 (30.4°C), and the RR was the highest in the ?65 age group (1.863, 1.755 to 1.978). The threshold temperature of the provinces (30.5°C) was lower than that of the metropolitan cities (32.2°C). Metropolitan cities at higher latitudes had a greater RR than other cities at lower latitudes. Conclusion The influences of temperature on heat-related illnesses vary according to gender, age, and region. A surveillance system and public health program should reflect these factors in their implementation.

Sensitivity to heat: A comparative study of Phoenix, Arizona and Chicago, Illinois (2003–2006)

Research on how heat impacts human health has increased as climate change threatens to raise temperatures to new extremes. Excessive heat exposure increases death rates, as well as rates of nonfatal, adverse health outcomes. This study used the negative binomial regression model to examine the relationship between daily maximum temperature, heat index, and heat-related emergency calls in Phoenix, Arizona and Chicago, Illinois, from 2003 to 2006. Using model results, we estimated call volumes in a warmer climate, with temperature increase from 1 to 5.5°C. We found that: (1) heat-stress calls increase sharply when the temperature exceeds about 35°C in Chicago and in 45°C Phoenix; (2) warmer climate could seriously threaten human health and existing emergency response system in Chicago more than in Phoenix. Policies to reduce heat impacts in Phoenix should focus on reducing prolonged heat exposure, while Chicago should build a strong early-warning system for extreme heat events and provide sufficient resources and infrastructure to mitigate heat stress during those events.