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BackgroundLiving in greener areas of cities was linked to increased physical activity levels, improved mental well-being, and lowered harmful environmental exposures, all of which may affect human health. However, whether living in greener areas may be associated with lower risk of cardiovascular disease incidence, progression, and premature mortality is unclear.ObjectivesWe conducted a cohort study to examine the associations between residential green spaces and the incidence of acute myocardial infarction (AMI) and heart failure (HF), post-AMI and HF hospital readmissions, and mortality.MethodsWe simultaneously followed four large population-based cohorts in Ontario, Canada, including the entire adult population, adults free of AMI and HF, and survivors of AMI or HF from 2000 to 2014. We estimated residential exposure to green spaces using satellite-derived observations and ascertained health outcomes using validated disease registries. We estimated the associations using spatial random-effects Cox proportional hazards models. We conducted various sensitivity analyses, including further adjusting for property values and performing exploratory mediation analysis.ResultsEach interquartile range increase in residential greenness was associated with a 7% [95% confidence interval (CI): 4%, 9%] decrease in incident AMI and a 6% (95% CI: 4%, 7%) decrease in incident HF. Residential greenness was linked to a ∼10% decrease in cardiovascular mortality in both adults free of AMI and HF and the entire adult population. These associations remained consistent in sensitivity analyses and were accentuated among younger adults. Additionally, we estimated that the decreases in AMI and HF incidence associated with residential greenness explained ∼53% of the protective association between residential greenness and cardiovascular mortality. Conversely, residential greenness was not associated with any delay in readmission or mortality among AMI and HF patients.ConclusionsLiving in urban areas with more green spaces was associated with improved cardiovascular health in people free of AMI and HF but not among individuals who have already developed these conditions. https://doi.org/10.1289/EHP6161.

BACKGROUND: Epidemiological evidence on the health risks of sulfur dioxide (S[O.sub.2]) is more limited compared with other pollutants, and doubts remain on several aspects, such as the form of the exposure-response relationship, the potential role of co-pollutants, as well as the actual risk at low concentrations and possible temporal variation in risks. OBJECTIVES: Our aim was to assess the short-term association between exposure to S[O.sub.2] and daily mortality in a large multilocation data set, using advanced study designs and statistical techniques. METHODS: The analysis included 43,729,018 deaths that occurred in 399 cities within 23 countries between 1980 and 2018. A two-stage design was applied to assess the association between the daily concentration of S[O.sub.2] and mortality counts, including first-stage time-series regressions and second-stage multilevel random-effect meta-analyses. Secondary analyses assessed the exposure-response shape and the lag structure using spline terms and distributed lag models, respectively, and temporal variations in risk using a longitudinal meta- regression. Bi-pollutant models were applied to examine confounding effects of particulate matter with an aerodynamic diameter of RESULTS: The average daily concentration of S[O.sub.2] across the 399 cities was 11.7 [micro]g/[m.sup.3], with 4.7% of days above the World Health Organization (WHO) guideline limit (40 [micro]g/[m.sup.3], 24-h average), although the exceedances occurred predominantly in specific locations. Exposure levels decreased considerably during the study period, from an average concentration of 19.0 [micro]g/[m.sup.3] in 1980-1989 to 6.3 [micro]g/[m.sup.3] in 2010-2018. For all locations combined, a 10-[micro]g/[m.sup.3] increase in daily S[O.sub.2] was associated with an RR of mortality of 1.0045 [95% confidence interval (CI): 1.0019, 1.0070], with the risk being stable over time but with substantial between-country heterogeneity. Short-term exposure to S[O.sub.2] was associated with an excess mortality fraction of 0.50% [95% empirical CI (eCI): 0.42%, 0.57%] in the 399 cities, although decreasing from 0.74% (0.61%, 0.85%) in 1980-1989 to 0.37% (0.27%, 0.47%) in 2010-2018. There was some evidence of nonlinearity, with a steep exposure-response relationship at low concentrations and the risk attenuating at higher levels. The relevant lag window was 0-3 d. Significant positive associations remained after controlling for other pollutants. DISCUSSION: The analysis revealed independent mortality risks associated with short-term exposure to S[O.sub.2], with no evidence of a threshold. Levels below the current WHO guidelines for 24-h averages were still associated with substantial excess mortality, indicating the potential benefits of stricter air quality standards. https://doi.org/10.1289/EHP11112, Introduction Sulfur dioxide (S[O.sub.2]) is an important air pollutant linked with increased health risks. (1,2) It originates largely from the combustion of fossil fuels to generate electricity and transportation. (1,3,4) [...]

Background: We do not currently understand how spatiotemporal variations in the composition of fine particulate air pollution [fine particulate matter with aerodynamic diameter [less than or equal to] 2.5 [micro]m ([PM.sub.2.5])] affects population health risks. However, recent evidence suggests that joint concentrations of transition metals and sulfate may influence the oxidative potential (OP) of [PM.sub.2.5] and associated health impacts. Objectives: The purpose of the study was to evaluate how combinations of transition metals/OP and sulfur content in outdoor [PM.sub.2.5] influence associations with acute cardiovascular events. Methods: We conducted a national case-crossover study of outdoor [PM.sub.2.5] and acute cardiovascular events in Canada between 2016 and 2017 (93,344 adult cases). Monthly mean transition metal and sulfur (S) concentrations in [PM.sub.2.5] were determined prospectively along with estimates of OP using acellular assays for glutathione ([OP.sup.GSH]), ascorbate ([OP.sup.AA]), and dithiothreitol depletion ([OP.sup.DTT]). Conditional logistic regression models were used to estimate odds ratios (OR) [95% confidence intervals (CI)] for [PM.sub.2.5] across strata of transition metals/OP and sulfur. Results: Among men, the magnitudes of observed associations were strongest when both transition metal and sulfur content were elevated. For example, an OR of 1.078 (95% CI: 1.049, 1.108) (per 10 [micro]g/[m.sup.3]) was observed for cardiovascular events in men when both copper and S were above the median, whereas a weaker association was observed when both elements were below median values (OR= 1.019, 95% CI: 1.007, 1.031). A similar pattern was observed for OP metrics. [PM.sub.2.5] was not associated with acute cardiovascular events in women. Discussion: The combined transition metal and sulfur content of outdoor [PM.sub.2.5] influences the strength of association with acute cardiovascular events in men. Regions with elevated concentrations of both sulfur and transition metals in [PM.sub.2.5] should be examined as priority areas for regulatory interventions. https://doi.org/10.1289/EHP9449, Introduction Numerous epidemiological studies have documented the acute cardio-respiratory health impacts of outdoor fine particulate air pollution [fine particulate matter with aerodynamic diameter [less than or equal to] 2.5 [micro]m [...]

Background: Previous literature suggests that higher ambient temperature may play a role in increasing the risk of suicide. However, no multicountry study has explored the shape of the association and the role of moderate and extreme heat across different locations. Objectives: We examined the short-term temperature-suicide relationship using daily time-series data collected for 341 locations in 12 countries for periods ranging from 4 to 40 y. Methods: We conducted a two-stage meta-analysis. First, we performed location-specific time-stratified case-crossover analyses to examine the temperature-suicide association for each location. Then, we used a multivariate meta-regression to combine the location-specific lag-cumulative nonlinear associations across all locations and by country. Results: A total of 1,320,148 suicides were included in this study. Higher ambient temperature was associated with an increased risk of suicide in general, and we observed a nonlinear association (inverted J-shaped curve) with the highest risk at 27[degrees]C. The relative risk (RR) for the highest risk was 1.33 (95% CI: 1.30, 1.36) compared with the risk at the first percentile. Country-specific results showed that the nonlinear associations were more obvious in northeast Asia (Japan, South Korea, and Taiwan). The temperature with the highest risk of suicide ranged from the 87th to 88th percentiles in the northeast Asian countries, whereas this value was the 99th percentile in Western countries (Canada, Spain, Switzerland, the UK, and the United States) and South Africa, where nearly linear associations were estimated. The country-specific RRs ranged from 1.31 (95% CI: 1.19, 1.44) in the United States to 1.65 (95% CI: 1.40, 1.93) in Taiwan, excluding countries where the results were substantially uncertain. Discussion: Our findings showed that the risk of suicide increased with increasing ambient temperature in many countries, but to varying extents and not necessarily linearly. This temperature-suicide association should be interpreted cautiously, and further evidence of the relationship and modifying factors is needed. https://doi.org/10.1289/EHP4898, Introduction Suicide is a significant public health concern. It is the second leading cause of death among young people 15-29 years of age, and there were an estimated 803,900 deaths [...]

During editing, the article title, 'The Role of Humidity in Associations of High Temperature with Mortality: A Multicountry, Multicity Study,' was inadvertently changed to 'The Role of Humidity in Associations [...]

Background: There is strong experimental evidence that physiologic stress from high temperatures is greater if humidity is higher. However, heat indices developed to allow for this have not consistently predicted mortality better than dry-bulb temperature. Objectives: We aimed to clarify the potential contribution of humidity an addition to temperature in predicting daily mortality in summer by using a large multicountry dataset. Methods: In 445 cities in 24 countries, we fit a time-series regression model for summer mortality with a distributed lag nonlinear model (DLNM) for temperature (up to lag 3) and supplemented this with a range of terms for relative humidity (RH) and its interaction with temperature. City-specific associations were summarized using meta-analytic techniques. Results: Adding a linear term for RH to the temperature term improved fit slightly, with an increase of 23% in RH (the 99th percentile anomaly) associated with a 1.1% [95% confidence interval (CI): 0.8, 1.3] decrease in mortality. Allowing curvature in the RH term or adding terms for interaction of RH with temperature did not improve the model fit. The humidity-related decreased risk was made up of a positive coefficient at lag 0 outweighed by negative coefficients at lags of 1-3 d. Key results were broadly robust to small model changes and replacing RH with absolute measures of humidity. Replacing temperature with apparent temperature, a metric combining humidity and temperature, reduced goodness of fit slightly. Discussion: The absence of a positive association of humidity with mortality in summer in this large multinational study is counter to expectations from physiologic studies, though consistent with previous epidemiologic studies finding little evidence for improved prediction by heat indices. The result that there was a small negative average association of humidity with mortality should be interpreted cautiously; the lag structure has unclear interpretation and suggests the need for future work to clarify. https://doi.org/10.1289/EHP5430, Introduction There is strong experimental physiologic evidence that the stress put on the human organism by high air temperatures is higher, by many measures, if humidity is higher, in particular [...]

Background: Few studies have examined variation in the associations between heat waves and mortality in an international context. Objectives: We aimed to systematically examine the impacts of heat waves on mortality with lag effects internationally. Methods: We collected daily data of temperature and mortality from 400 communities in 18 countries/regions and defined 12 types of heat waves by combining community-specific daily mean temperature [greater than or equal to] 90th, 92.5th, 95th, and 97.5th percentiles of temperature with duration [greater than or equal to] 2, 3, and 4 d. We used time-series analyses to estimate the community-specific heat wave-mortality relation over lags of 0-10 d. Then, we applied meta-analysis to pool heat wave effects at the country level for cumulative and lag effects for each type of heat wave definition. Results: Heat waves of all definitions had significant cumulative associations with mortality in all countries, but varied by community. The higher the temperature threshold used to define heat waves, the higher heat wave associations on mortality. However, heat wave duration did not modify the impacts. The association between heat waves and mortality appeared acutely and lasted for 3 and 4 d. Heat waves had higher associations with mortality in moderate cold and moderate hot areas than cold and hot areas. There were no added effects of heat waves on mortality in all countries/regions, except for Brazil, Moldova, and Taiwan. Heat waves defined by daily mean and maximum temperatures produced similar heat wave-mortality associations, but not daily minimum temperature. Conclusions: Results indicate that high temperatures create a substantial health burden, and effects of high temperatures over consecutive days are similar to what would be experienced if high temperature days occurred independently. People living in moderate cold and moderate hot areas are more sensitive to heat waves than those living in cold and hot areas. Daily mean and maximum temperatures had similar ability to define heat waves rather than minimum temperature. https://doi.org/10.1289/EHP1026, Introduction Globally, there is increasing interest in assessing heat wave-related health effects after major heat waves in the United States and Europe, for example, Chicago in 1995 and Europe in [...]

BACKGROUND: The evidence and method are limited for the associations between mortality and temperature variability (TV) within or between days. OBJECTIVES: We developed a novel method to calculate TV and investigated TV-mortality associations using a large multicountry data set. METHODS: We collected daily data for temperature and mortality from 372 locations in 12 countries/regions (Australia, Brazil, Canada, China, Japan, Moldova, South Korea, Spain, Taiwan, Thailand, the United Kingdom, and the United States). We calculated TV from the standard deviation of the minimum and maximum temperatures during the exposure days. Two-stage analyses were used to assess the relationship between TV and mortality. In the first stage, a Poisson regression model allowing over-dispersion was used to estimate the community-specific TV-mortality relationship, after controlling for potential confounders. In the second stage, a meta-analysis was used to pool the effect estimates within each country. RESULTS: There was a significant association between TV and mortality in all countries, even after controlling for the effects of daily mean temperature. In stratified analyses, TV was still significantly associated with mortality in cold, hot, and moderate seasons. Mortality risks related to TV were higher in hot areas than in cold areas when using short TV exposures (0-1 days), whereas TV-related mortality risks were higher in moderate areas than in cold and hot areas when using longer TV exposures (0-7 days). CONCLUSIONS: The results indicate that more attention should be paid to unstable weather conditions in order to protect health. These findings may have implications for developing public health policies to manage health risks of climate change. http://dx.doi.org/10.1289/EHP149, Introduction Time series data on daily air pollution concentrations, weather conditions, and daily measures of health outcomes (e.g., mortality, hospital admissions), have been used to assess how environmental factors may [...]

BACKGROUND: We do not currently understand how spatiotemporal variations in the composition of fine particulate air pollution [fine particulate matter with aerodynamic diameter  = 2.5 µ m  (PM2.5)] affects population health risks. However, recent evidence suggests that joint concentrations of transition metals and sulfate may influence the oxidative potential (OP) of  PM2.5  and associated health impacts. OBJECTIVES: The purpose of the study was to evaluate how combinations of transition metals/OP and sulfur content in outdoor  PM2.5  influence associations with acute cardiovascular events. METHODS: We conducted a national case-crossover study of outdoor  PM2.5  and acute cardiovascular events in Canada between 2016 and 2017 (93,344 adult cases). Monthly mean transition metal and sulfur (S) concentrations in  PM2.5  were determined prospectively along with estimates of OP using acellular assays for glutathione (OP GSH), ascorbate (OP AA), and dithiothreitol depletion (OP DTT). Conditional logistic regression models were used to estimate odds ratios (OR) [95% confidence intervals (CI)] for  PM2.5  across strata of transition metals/OP and sulfur. RESULTS: Among men, the magnitudes of observed associations were strongest when both transition metal and sulfur content were elevated. For example, an OR of 1.078 (95% CI: 1.049, 1.108) (per  10µg/m3) was observed for cardiovascular events in men when both copper and S were above the median, whereas a weaker association was observed when both elements were below median values (OR = 1.019, 95% CI: 1.007, 1.031). A similar pattern was observed for OP metrics.  PM2.5  was not associated with acute cardiovascular events in women. DISCUSSION: The combined transition metal and sulfur content of outdoor  PM2.5  influences the strength of association with acute cardiovascular events in men. Regions with elevated concentrations of both sulfur and transition metals in  PM2.5  should be examined as priority areas for regulatory interventions. https://doi.org/10.1289/EHP9449. [ABSTRACT FROM AUTHOR]

BACKGROUND: Recent investigations have reported a decline in the heat-related mortality risk during the last decades. However, these studies are frequently based on modeling approaches that do not fully characterize the complex temperature-mortality relationship, and are limited to single cities or countries. OBJECTIVES: We assessed the temporal variation in heat-mortality associations in a multi-country data set using flexible modelling techniques. METHODS: We collected data for 272 locations in Australia, Canada, Japan, South Korea, Spain, the United Kingdom, and the United States, with a total 20,203,690 deaths occurring in summer months between 1985 and 2012. The analysis was based on two-stage time-series models. The temporal variation in heat-mortality relationships was estimated in each location with time-varying distributed lag nonlinear models, expressed through an interaction between the transformed temperature variables and time. The estimates were pooled by country through multivariate meta-analysis. RESULTS: Mortality risk due to heat appeared to decrease over time in several countries, with relative risks associated to high temperatures significantly lower in 2006 compared with 1993 in the United States, Japan, and Spain, and a nonsignificant decrease in Canada. Temporal changes are difficult to assess in Australia and South Korea due to low statistical power, and we found little evidence of variation in the United Kingdom. In the United States, the risk seems to be completely abated in 2006 for summer temperatures below their 99th percentile, but some significant excess persists for higher temperatures in all the countries. CONCLUSIONS: We estimated a statistically significant decrease in the relative risk for heat-related mortality in 2006 compared with 1993 in the majority of countries included in the analysis. http://dx.doi.org/10.1289/ehp.1409070, Introduction High ambient temperature is an established risk factor for human health, with overwhelming evidence on the associated excess risk for mortality or morbidity outcomes (Basu 2009; Basu and Samet [...]

BACKGROUND: Prenatal exposure to fine particulate matter air pollution with aerodynamic diameter [less than or equal to] 2.5 [micro]m ([PM.sub.2.5]) has been associated with preterm delivery and low birth weight (LBW), but few studies have examined possible effect modification by [PM.sub.2.5] oxidative potential. OBJECTIVES: The aim of this study was to evaluate if regional differences in the oxidative potential of [PM.sub.2.5] modify the relationship between [PM.sub.2.5] and adverse birth outcomes. METHODS: A retrospective cohort study was conducted using 196,171 singleton births that occurred in 31 cities in the province of Ontario, Canada, from 2006 to 2012. Daily air pollution data were collected from ground monitors, and city-level [PM.sub.2.5] oxidative potential was measured. We used random-effects meta-analysis to combine the estimates of effect from regression models across cities on preterm birth, term LBW, and term birth weight and used meta-regression to evaluate the modifying effect of [PM.sub.2.5] oxidative potential. RESULTS: An interquartile increase (2.6 [micro]g/[m.sup.3]) in first-trimester [PM.sub.2.5] was positively associated with term LBW among women in the highest quartile of glutathione (GSH)-related oxidative potential [odds ratio (OR)= 1.28; 95% confidence interval (CI): 1.10, 1.48], but not the lowest quartile (OR = 0.99; 95% CI: 0.87, 1.14; p-interaction = 0.03). [PM.sub.2.5] on the day of delivery also was associated with preterm birth among women in the highest quartile of GSH-related oxidative potential [hazard ratio (HR) = 1.02; 95% CI: 1.01, 1.04], but not the lowest quartile [HR = 0.97; 95% CI: 0.95, 1.00; p-interaction = 0.04]. Between-city differences in ascorbate (AA)-related oxidative potential did not significantly modify associations with [PM.sub.2.5]. CONCLUSIONS: Between-city differences in GSH-related oxidative potential may modify the impact of [PM.sub.2.5] on the risk of term LBW and preterm birth., Introduction A large number of studies have suggested associations between ambient fine particulate matter with aerodynamic diameter [less than or equal to] 2.5 [micro]m ([PM.sub.2.5]) and adverse birth outcomes, with [...]

BACKGROUND: Living in greener areas of cities was linked to increased physical activity levels, improved mental well-being, and lowered harmful environmental exposures, all of which may affect human health. However, whether living in greener areas may be associated with lower risk of cardiovascular disease incidence, progression, and premature mortality is unclear. OBJECTIVES: We conducted a cohort study to examine the associations between residential green spaces and the incidence of acute myocardial infarction (AMI) and heart failure (HF), post-AMI and HF hospital readmissions, and mortality. METHODS: We simultaneously followed four large population-based cohorts in Ontario, Canada, including the entire adult population, adults free of AMI and HF, and survivors of AMI or HF from 2000 to 2014. We estimated residential exposure to green spaces using satellite-derived observations and ascertained health outcomes using validated disease registries. We estimated the associations using spatial random-effects Cox proportional hazards models. We conducted various sensitivity analyses, including further adjusting for property values and performing exploratory mediation analysis. RESULTS: Each interquartile range increase in residential greenness was associated with a 7% [95% confidence interval (CI): 4%, 9%] decrease in incident AMI and a 6% (95% CI: 4%, 7%) decrease in incident HF. Residential greenness was linked to a ~10% decrease in cardiovascular mortality in both adults free of AMI and HF and the entire adult population. These associations remained consistent in sensitivity analyses and were accentuated among younger adults. Additionally, we estimated that the decreases in AMI and HF incidence associated with residential greenness explained ~53% of the protective association between residential greenness and cardiovascular mortality. Conversely, residential greenness was not associated with any delay in readmission or mortality among AMI and HF patients. CONCLUSIONS: Living in urban areas with more green spaces was associated with improved cardiovascular health in people free of AMI and HF but not among individuals who have already developed these conditions. [ABSTRACT FROM AUTHOR]

Background: In many places, daily mortality has been shown to increase after days with particularly high or low temperatures, but such daily time-series studies cannot identify whether such increases reflect substantial life shortening or short-term displacement of deaths (harvesting). Objectives: To clarify this issue, we estimated the association between annual mortality and annual summaries of heat and cold in 278 locations from 12 countries. Methods: Indices of annual heat and cold were used as predictors in regressions of annual mortality in each location, allowing for trends over time and clustering of annual count anomalies by country and pooling estimates using meta-regression. We used two indices of annual heat and cold based on preliminary standard daily analyses: a) mean annual degrees above/below minimum mortality temperature (MMT), and b) estimated fractions of deaths attributed to heat and cold. The first index was simpler and matched previous related research; the second was added because it allowed the interpretation that coefficients equal to 0 and 1 are consistent with none (0) or all (1) of the deaths attributable in daily analyses being displaced by at least 1 y. Results: On average, regression coefficients of annual mortality on heat and cold mean degrees were 1.7% [95% confidence interval (CI): 0.3, 3.1] and 1.1% (95% CI: 0.6, 1.6) per degree, respectively, and daily attributable fractions were 0.8 (95% CI: 0.2, 1.3) and 1.1 (95% CI: 0.9, 1.4). The proximity of the latter coefficients to 1.0 provides evidence that most deaths found attributable to heat and cold in daily analyses were brought forward by at least 1 y. Estimates were broadly robust to alternative model assumptions. Conclusions: These results provide strong evidence that most deaths associated in daily analyses with heat and cold are displaced by at least 1 y. https://doi.org/10.1289/EHP1756, Introduction In many locations worldwide, daily time-series analyses have identified adverse associations between daily mortality and temperatures that are toward the hot and cold ends of the temperature range for [...]

BACKGROUND: Previous literature suggests that higher ambient temperature may play a role in increasing the risk of suicide. However, no multicountry study has explored the shape of the association and the role of moderate and extreme heat across different locations. OBJECTIVES: We examined the short-term temperature–suicide relationship using daily time-series data collected for 341 locations in 12 countries for periods ranging from 4 to 40 y. METHODS: We conducted a two-stage meta-analysis. First, we performed location-specific time-stratified case-crossover analyses to examine the temperature–suicide association for each location. Then, we used a multivariate meta-regression to combine the location-specific lag-cumulative nonlinear associations across all locations and by country. RESULTS: A total of 1,320,148 suicides were included in this study. Higher ambient temperature was associated with an increased risk of suicide in general, and we observed a nonlinear association (inverted J-shaped curve) with the highest risk at 27°C. The relative risk (RR) for the highest risk was 1.33 (95% CI: 1.30, 1.36) compared with the risk at the first percentile. Country-specific results showed that the nonlinear associations were more obvious in northeast Asia (Japan, South Korea, and Taiwan). The temperature with the highest risk of suicide ranged from the 87th to 88th percentiles in the northeast Asian countries, whereas this value was the 99th percentile in Western countries (Canada, Spain, Switzerland, the UK, and the United States) and South Africa, where nearly linear associations were estimated. The country-specific RRs ranged from 1.31 (95% CI: 1.19, 1.44) in the United States to 1.65 (95% CI: 1.40, 1.93) in Taiwan, excluding countries where the results were substantially uncertain. DISCUSSION: Our findings showed that the risk of suicide increased with increasing ambient temperature in many countries, but to varying extents and not necessarily linearly. This temperature–suicide association should be interpreted cautiously, and further evidence of the relationship and modifying factors is needed. [ABSTRACT FROM AUTHOR]

BACKGROUND: Few studies have examined variation in the associations between heat waves and mortality in an international context. OBJECTIVES: We aimed to systematically examine the impacts of heat waves on mortality with lag effects internationally. METHODS: We collected daily data of temperature and mortality from 400 communities in 18 countries/regions and defined 12 types of heat waves by combining community-specific daily mean temperature ≥90th, 92.5th, 95th, and 97.5th percentiles of temperature with duration ≥2, 3, and 4 d. We used time-series analyses to estimate the community-specific heat wave-mortality relation over lags of 0-10 d. Then, we applied meta-analysis to pool heat wave effects at the country level for cumulative and lag effects for each type of heat wave definition. RESULTS: Heatwaves of all definitions had significant cumulative associationswithmortality in all countries, but varied by community. The higher the temperature threshold used to define heatwaves, the higher heatwave associations onmortality. However, heatwave duration did notmodify the impacts. The association between heat waves and mortality appeared acutely and lasted for 3 and 4 d. Heat waves had higher associations with mortality in moderate cold and moderate hot areas than cold and hot areas. Therewere no added effects of heat waves onmortality in all countries/regions, except for Brazil, Moldova, and Taiwan. Heat waves defined by dailymean andmaximumtemperatures produced similar heatwave-mortality associations, but not dailyminimum temperature. CONCLUSIONS: Results indicate that high temperatures create a substantial health burden, and effects of high temperatures over consecutive days are similar to what would be experienced if high temperature days occurred independently. People living in moderate cold and moderate hot areas are more sensitive to heat waves than those living in cold and hot areas. Daily mean and maximum temperatures had similar ability to define heat waves rather than minimum temperature. [ABSTRACT FROM AUTHOR]