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The link between outdoor temperature and risk of drowning in children is poorly understood. The objective of this study was to determine the association between elevated temperature and the chance of drowning in children and adolescents. We used a case-crossover study design to assess 807 fatal and nonfatal drowning-related hospitalisations among children aged 0 to 19 years in Quebec, Canada between 1989 and 2015. The primary exposure measure was maximum temperature the day of drowning. We estimated odds ratios and 95% confidence intervals (CI) for the association of temperature with drowning by age group (<2, 2-4, 5-9, 10-19 years), adjusted for precipitation, relative humidity, and holidays. Elevated temperature was associated with greater odds of drowning. Compared with 15 °C, a temperature of 30 °C was associated with 6 times the chance of drowning between 0 and 19 years of age (95% CI 4.40-8.16). The association was not modified by characteristics such as age or location of drowning. Relative to 15 °C, a temperature of 30 °C was associated with 3.75 times the odds of drowning in pools (95% CI 1.85-7.63) and 12.44 times the odds of drowning in other bodies of water (95% CI 3.53-43.81). Associations persisted even after implementation of a policy to restrict access to private pools in 2010. These findings suggest that hot weather is strongly associated with the risk of drowning in children aged 0 to 19 years. Interventions to prevent drowning in children should be enhanced during hot days, and not only around pools., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Introduction: Outdoor heat increases the risk of preterm birth and stillbirth, but the association with placental abruption has not been studied. Placental abruption is a medical emergency associated with major morbidity and mortality in pregnancy. We determined the relationship between ambient temperature and risk of placental abruption in warm seasons., Material and Methods: We performed a case-crossover analysis of 17,172 women whose pregnancies were complicated by placental abruption in Quebec, Canada from May to October 1989-2012. The main exposure measure was the maximum temperature reached during the week before abruption. We computed odds ratios (OR) and 95% confidence intervals (CI) for the association of temperature with placental abruption, adjusted for humidity and public holidays. We assessed whether associations were stronger preterm or at term, or varied with maternal age, parity, comorbidity and socioeconomic status., Results: Compared with 15°C, a maximum weekly temperature of 30°C was associated with 1.07 times the odds of abruption (95% CI 0.99-1.16). When the timing of abruption was examined, the associations were significantly stronger at term (OR 1.12, 95% CI 1.02-1.24) than preterm (OR 0.96, 95% CI 0.83-1.10). Relationships were more prominent at term for women who were younger than 35years old, nulliparous or socioeconomically disadvantaged, but did not vary with comorbidity. Associations were stronger within 1 and 5days of abruption. Temperature was not associated with preterm abruption regardless of maternal characteristics., Conclusions: Elevated temperatures in warm seasons may increase the risk of abruption in women whose pregnancies are near or at term. Pregnant women may be more sensitive to heat and should consider preventive measures such as air conditioning and hydration during hot weather., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: Retinal detachment is an important cause of visual loss, but the association with outdoor heat exposure has not been studied. Our objective was to determine the relationship between acute exposure to high outdoor temperature and risk of retinal detachment., Materials and Methods: We analysed 14,302 individuals with inpatient procedures for retinal detachment from April through September between 2006 and 2013 in the province of Quebec, Canada. Using a time-stratified case-crossover study design, we examined the association of retinal detachment with outdoor summer temperature the preceding week. We estimated odds ratios (OR) and 95% confidence intervals (CI) for mean weekly temperature according to subtypes of retinal detachment (traction, serous, rhegmatogenous, breaks), and assessed associations by age and sex., Results: Exposure to elevated temperature the preceding week was associated with a higher likelihood of traction detachment, but not other forms of retinal detachment. Associations were stronger at <75 years of age in both men and women. Relative to 15°C, a mean weekly temperature of 25°C was associated with an OR for traction detachment of 2.71 (95% CI 1.56-4.71) before 55 years, 2.73 (95% CI 1.61-4.64) at 55-64 years, and 1.98 (95% CI 1.30-3.02) at 64-75 years., Discussion: Elevated outdoor temperatures may be associated with an increased risk of traction retinal detachment. In light of climate change, a better understanding of the impact of heat waves on the eye and other sensory organs is needed., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objectives: The association between ambient heat and neural tube defects has received limited attention, despite imminent climate warming this century. We sought to determine the relationship between elevated outdoor temperatures during neurogenesis and risk of neural tube defects., Methods: We carried out a retrospective cohort study of 887 710 fetuses between 3 and 4 weeks postconception from the months of April through September for 1988-2012 in Quebec, Canada. The exposure was maximum daily temperature and the outcome presence of neural tube defects at delivery. We estimated prevalence ratios (PR) and 95% CIs for the association between maximum temperature and neural tube defects in log-binomial regression models adjusted for maternal characteristics., Results: Relative to 20°C, exposure to temperatures of 30°C was associated with risk of neural tube defects on day 5 (PR 1.56, 95% CI 1.04 to 2.35) and day 6 (PR 1.49, 95% CI 1.00 to 2.21) of the 4th week postconception, during the time of neural tube closure. The trend was apparent for spina bifida and anencephalus/encephalocoele, the main subtypes of neural tube defects. Temperature during the 3rd week postconception was not associated with neural tube defects., Conclusions: Elevated ambient temperatures may be weakly associated with risk of neural tube defects during tube closure., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.)

Background: The causes of stillbirth are poorly understood, including whether elevated outdoor temperatures increase risk. We assessed the relationship between elevated ambient temperatures and risk of stillbirth by gestational age and cause of death during warm months in a temperate region., Methods: We performed a case-crossover study of 5047 stillbirths in continental Quebec, Canada, between the months of April through September from 1981 to 2011. Using data on maximum daily temperatures adjusted for relative humidity, we estimated associations with stillbirth, comparing temperatures before fetal death with temperatures on adjacent days. The main outcomes were stillbirth according to age of gestation (term, preterm), and cause of death (undetermined, maternal, placenta/cord/membranes, birth asphyxia, congenital anomaly, other)., Results: Elevated outdoor temperatures the week before the death were more strongly associated with risk of term than preterm stillbirth. Odds of term stillbirth for temperature 28 °C the day before death were 1.16 times greater relative to 20 °C (95% confidence interval, CI 1.02-1.33). Elevated outdoor temperature was associated with stillbirth due to undetermined and maternal causes, but not other causes. Compared with 20 °C, the odds of stillbirth at 28 °C were 1.19 times greater for undetermined causes (95% CI 1.02-1.40) and 1.46 times greater for maternal complications (95% CI 1.03-2.07)., Conclusions: Elevated outdoor temperatures may be a risk factor for term stillbirth, including stillbirth due to undetermined causes or maternal complications., (© The Author 2016; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association)

Background: Climate change may lead to more severe and extreme heat waves in the future, but its potential impact on sudden infant death-a leading cause of infant mortality-is unclear., Objectives: We sought to determine whether risk of sudden infant death syndrome (SIDS) is elevated during hot weather., Methods: We undertook a case-crossover analysis of all sudden infant deaths during warm periods in metropolitan Montreal, Quebec, Canada, from 1981 through 2010. Our analysis included a total of 196 certified cases of SIDS, including 89 deaths at 1-2 months of age, and 94 at 3-12 months. We estimated associations between maximum outdoor temperatures and SIDS by comparing outdoor temperatures on the day of or day before a SIDS event with temperatures on control days during the same month, using cubic splines to model temperature and adjusting for relative humidity., Results: Maximum daily temperatures of ≥ 29°C on the same day were associated with 2.78 times greater odds of sudden infant death relative to 20°C (95% CI: 1.64, 4.70). The likelihood of sudden death increased steadily with higher temperature. Associations were stronger for infants 3-12 months of age than for infants 1-2 months of age, with odds ratios of 3.90 (95% CI: 1.87, 8.13) and 1.73 (95% CI: 0.80, 3.73), respectively, for 29°C compared with 20°C on the day of the event., Conclusions: High ambient temperature may be a novel risk factor for SIDS, especially at ≥ 3 months of age. Climate change and the higher temperatures that result may account for a potentially greater proportion of sudden infant deaths in the future.

Temperature-mortality analyses are challenging in rural and remote communities with small populations, but this information is needed for climate change and emergency planning. The geographic health areas of British Columbia, Canada were aggregated into four ecoregions delineated by microclimatic conditions. Time series models were used to estimate the effect of maximum apparent temperature on daily non-traumatic mortality. The population of the coldest ecoregion was most sensitive to hot weather, while the population of the hottest ecoregion was least sensitive. The effects were consistently strongest in decedents aged less than 75 years. A province-wide total of 815 deaths was attributed to hot weather over the 25-year study period, with 735 deaths in the most populous ecoregion. The framework described could be adapted to other climatically variable regions with urban, rural, and remote populations., (Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Efforts to prevent and respond to heat-related illness would benefit by quantifying the impact of summer heat on acute population mortality. We estimated years of life lost due to heat in 14 European cities during the 1990s accounting for harvesting., Methods: We combined the number of deaths attributable to heat estimated by the PHEWE project with life expectancy derived from population life tables. The degree of harvesting was quantified by comparing the cumulative effect of heat up to lagged day 30 with the immediate effect of heat, by geographical region and age. Next, an evaluation of years of life lost adjusted for harvesting was obtained., Results: Without accounting for harvesting, we estimated more than 23,000 years of life lost per year, 55% of which was among individuals younger than 75. When 30 day mortality displacement was taken into account, the overall impact reduced on average by 75%. Harvesting was more pronounced in North-continental cities than in Mediterranean cities and was stronger among young people than among elderly., Conclusions: High ambient temperatures during summer were responsible for many deaths in European cities during the 1990s, but a large percentage of these deaths likely involved frail persons whose demise was only briefly hastened by heat exposure. Differences in harvesting across regions and classes of age could reflect different proportions of frail individuals in the population or could be indicative of heterogeneous dynamics underlying the entry and exit of individuals from the high-risk pool which is subject to mortality displacement.

Objectives: We assessed shifts in patterns of mortality during a hot weather event in greater Vancouver, British Columbia., Methods: We used a case-only analysis to compare characteristics of individuals who died during the hottest week of 2009 with those who died (1) during earlier summer weeks in 2009 and (2) during the same calendar weeks in the summers of 2001 through 2008., Results: Compared with the 8 previous weeks of 2009, odds of mortality during the summer's hottest week were highest in the 65 to 74 years age category, compared with the 85 years and older category (odds ratio [OR] = 1.47; 95% confidence interval [CI] = 1.06, 2.03). The number of deaths at home increased over deaths in hospitals or institutions (OR = 1.43; 95% CI = 1.10, 1.86). Densely populated administrative health areas were more affected., Conclusions: A shift toward deaths at home suggests that in-home-based protective measures should be part of planning for hot weather events in greater Vancouver. Targeting should be considered for those aged 65 to 74 years. The case-only approach is quick and easy to apply and can provide useful information about localized, time-limited events.

Objectives: Unprecedentedly hot weather during the summer of 2009 resulted in considerable excess mortality in Greater Vancouver, Canada. Local municipalities and public health authorities requested a rapid, evidence-based recommendation for the temperature above which emergency action plans should be triggered to reduce potentially-avoidable mortality during future events., Methods: Candidate trigger temperatures were identified by examining the coincidence of extreme mortality days with extreme temperature days, using temperatures observed at two regional airports. Days when the two coincided between 2005 and 2009 were defined as historical heat health emergencies. Forecast and observed temperatures were combined in multiple early warning scenarios to retrospectively test the capacity to predict those heat health emergency dates, and results were expressed in terms of true positive (emergency predicted when one occurred) and false positive (emergency predicted when one did not occur) triggers., Results: Extreme mortality was observed when the 2-day average of maximum temperatures was > or =31 degrees C at the coastal airport and > or =36 degrees C at the inland airport. When observed and forecast temperatures were combined in different early warning scenarios, all historical heat health emergencies were correctly identified in four of twelve cases, with a minimum of two false positive triggers., Conclusions: A heat health emergency should be triggered for Greater Vancouver when the average of the current day's 14:00 observed temperature and the next day's forecast high is > or =29 degrees C on the coast and/or > or =34 degrees C inland. This condition provided 19 hours of lead time for preparation and was clearly understood by emergency responders and other users.

Extreme ambient heat is a serious public health threat, especially for the elderly and persons with pre-existing health conditions. Although much of the excess mortality and morbidity associated with extreme heat is preventable, the adoption of effective preventive strategies is limited. The study reported here tested the predictive power of selected components of the Health Belief Model for air-conditioning (AC) use among 238 non-institutionalized middle-aged and older adults with chronic heart failure and/or chronic obstructive pulmonary disease living in Montréal, Canada. Respondents were recruited through clinics (response rate 71%) and interviews were conducted in their homes or by telephone. Results showed that 73% of participants reported having a home air conditioner. The average number of hours spent per 24-hour period in air-conditioned spaces during heat waves was 14.5 hours (SD = 9.4). Exploratory structural equation modeling showed that specific beliefs about the benefits of and drawbacks to AC as well as internal cues to action were predictive of its level of use, whereas the perceived severity of the effects of heat on health was not. The findings are discussed in light of the need to adequately support effective response to extreme heat in this vulnerable population.

Background: The evaluation of exposure to ambient temperatures in epidemiological studies has generally been based on records from meteorological stations which may not adequately represent local temperature variability. Here we propose a spatially explicit model to estimate local exposure to temperatures of large populations under various meteorological conditions based on satellite and meteorological data., Methods: A general linear model was used to estimate surface temperatures using 15 LANDSAT 5 and LANDSAT 7 images for Quebec Province, Canada between 1987 and 2002 and spanning the months of June to August. The images encompassed both rural and urban landscapes and predictors included: meteorological records of temperature and wind speed, distance to major water bodies, Normalized Differential Vegetation Index (NDVI), land cover (built and bare land, water, or vegetation), latitude, longitude, and week of the year., Results: The model explained 77% of the variance in surface temperature, accounting for both temporal and spatial variations. The standard error of estimates was 1.42°C. Land cover and NDVI were strong predictors of surface temperature., Conclusions: This study suggests that a statistical approach to estimating surface temperature incorporating both spatially explicit satellite data and time-varying meteorological data may be relevant to assessing exposure to heat during the warm season in the Quebec. By allowing the estimation of space- and time-specific surface temperatures, this model may also be used to assess the possible impacts of land use changes under various meteorological conditions. It can be applied to assess heat exposure within a large population and at relatively fine-grained scale. It may be used to evaluate the acute health effect of heat exposure over long time frames. The method proposed here could be replicated in other areas around the globe for which satellite data and meteorological data is available.

Objectives: We compared the ability of several heat-health warning systems to predict days of heat-associated mortality using common data sets., Methods: Heat-health warning systems initiate emergency public health interventions once forecasts have identified weather conditions to breach predetermined trigger levels. We examined 4 commonly used trigger-setting approaches: (1) synoptic classification, (2) epidemiologic assessment of the temperature-mortality relationship, (3) temperature-humidity index, and (4) physiologic classification. We applied each approach in Chicago, Illinois; London, United Kingdom; Madrid, Spain; and Montreal, Canada, to identify days expected to be associated with the highest heat-related mortality., Results: We found little agreement across the approaches in which days were identified as most dangerous. In general, days identified by temperature-mortality assessment were associated with the highest excess mortality., Conclusions: Triggering of alert days and ultimately the initiation of emergency responses by a heat-health warning system varies significantly across approaches adopted to establish triggers.

Because of the increasing concerns about climate change and deadly heatwaves in the past, the health effects of hot weather are fast becoming a global public health challenge for the 21st century. Some cities across the world have introduced public health protection measures, with the timely provision of appropriate home-based prevention advice to the general public being the most crucial point of intervention. In this Review, we report current epidemiological and physiological evidence about the range of health effects associated with hot weather, and draw attention to the interplay between climate factors, human susceptibility, and adaptation measures that contribute to heat burdens. We focus on the evidence base for the most commonly provided heat-protection advice, and make recommendations about the optimum clinical and public health practice that are expected to reduce health problems associated with current and future hot weather., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Background: Epidemiologic studies show that high temperatures are related to mortality, but little is known about the exposure-response function and the lagged effect of heat. We report the associations between daily maximum apparent temperature and daily deaths during the warm season in 15 European cities., Methods: The city-specific analyses were based on generalized estimating equations and the city-specific results were combined in a Bayesian random effects meta-analysis. We specified distributed lag models in studying the delayed effect of exposure. Time-varying coefficient models were used to check the assumption of a constant heat effect over the warm season., Results: The city-specific exposure-response functions have a V shape, with a change-point that varied among cities. The meta-analytic estimate of the threshold was 29.4 degrees C for Mediterranean cities and 23.3 degrees C for north-continental cities. The estimated overall change in all natural mortality associated with a 1 degrees C increase in maximum apparent temperature above the city-specific threshold was 3.12% (95% credibility interval = 0.60% to 5.72%) in the Mediterranean region and 1.84% (0.06% to 3.64%) in the north-continental region. Stronger associations were found between heat and mortality from respiratory diseases, and with mortality in the elderly., Conclusions: There is an important mortality effect of heat across Europe. The effect is evident from June through August; it is limited to the first week following temperature excess, with evidence of mortality displacement. There is some suggestion of a higher effect of early season exposures. Acclimatization and individual susceptibility need further investigation as possible explanations for the observed heterogeneity among cities.

Background: Mortality during sustained periods of hot weather is generally regarded as being in excess of what would be predicted from smooth temperature-mortality gradients estimated using standard time-series regression models. However, the evidence for an effect of continuous days of exceptional heat ("heat wave effect") is indirect. In addition, because some interventions may be triggered only during forecasted heat waves, it would be helpful to know what fraction of all heat-related deaths falls during these specific periods and what fraction occurs throughout the remainder of the summer., Methods: Extended time-series data sets of daily mortality counts in 3 major European cities (London, 28 years of data; Budapest, 31 years; Milan, 18 years) were examined in relation to hot weather using a generalized estimating equations approach. We modeled temperature and specific heat wave terms using a variety of specifications., Results: With a linear effect of same-day temperature above an identified threshold, an additional "heat wave" effect of 5.5% was observed in London (95% confidence interval = 2.2 to 8.9), 9.3% in Budapest (5.8 to 13.0), and 15.2% in Milan (5.7 to 22.5). Heat wave effects were reduced slightly when we relaxed the linear assumption and these effects were reduced substantially when temperature was modeled as an average value of lags 0 to 2 days. In London, fewer than half of all heat-related deaths could be attributed to identified heat wave periods. In Milan and Budapest, the fraction was less than one fifth., Conclusions: Heat wave effects were apparent in simple time-series models but were reduced in multilag nonlinear models and small when compared with the overall summertime mortality burden of heat. Reduction of the overall heat burden requires preventive measures in addition to those that target warnings and responses uniquely to heat waves.

Background: Ecologic data suggest that elevated outdoor temperature is correlated with mortality rates from cocaine overdose. Using non-aggregated death records, we studied the association of hot temperatures with risk of death from cocaine overdose.Methods: We carried out a case-crossover study of all deaths from cocaine or other drug overdose between the months of May and September, from 2000 through 2013 in Quebec, Canada. We used conditional logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI) for the association between maximum outdoor temperature and death from cocaine or other drug overdose. The main outcome measure was death from cocaine overdose as a function of maximum temperature the day of death and the days immediately preceding death.Results: There were 316 deaths from cocaine overdose and 446 from other drug overdoses during the study. Elevated temperature the preceding week was associated with the likelihood of death from cocaine but not other drug overdose. Compared with 20°C, a maximum weekly temperature of 30°C was associated with an OR of 2.07 for death from cocaine overdose (95% CI 1.15-3.73), but an OR of 1.03 for other drug overdoses (95% CI 0.60-1.75). Associations for cocaine overdose were present with maximum daily temperature the day of and each of the three days preceding death.Conclusions: Elevated ambient temperature is associated with the risk of death from cocaine overdose. Public health practitioners and drug users should be aware of the added risk of mortality when cocaine is used during hot days. [ABSTRACT FROM AUTHOR]