BACKGROUND:Increasing urban vegetation coverage is associated with improved human health and well-being, reduced environmental impact of cities and enhanced urban resilience to climate change. OBJECTIVES:To support evidence-based urban planning, this study quantifies the mortality benefits, equity implications and cost-benefit ratio of several scenarios of green space development in Paris by 2040, including the replacement of car-dedicated surfaces with green spaces and a best-case scenario. METHODS:This quantitative health impact assessment is based on estimated changes in the Normalized Difference Vegetation Index (NDVI), obtained through the estimation of the dynamic effects over time using a Difference-in-Differences approach based on previous public greening interventions, and on an exposure-response relationship linking NDVI and all-cause mortality. It was conducted at the sub-municipal level (IRIS) and incorporates a social deprivation index to assess health equity implications. Vegetation costs are drawn from a previous French study estimating urban soil restoration prices. RESULTS:Replacing surplus on-street parking and 20% of street space with vegetation could reduce all-cause mortality by around 0.8%, while reaching 15% of vegetation coverage in each IRIS could prevent around 3% of deaths yearly in Paris as early as 2040. For all scenarios, these benefits were approximately equally distributed across deprivation levels. Predicted monetised health benefits outweigh intervention costs by 2035, with further impacts representing net gain. CONCLUSION:In conclusion, greening interventions targeting car-dedicated space in Paris would equitably improve health while supporting more sustainable and resilient cities.

Abstract Background Climate mitigation policies just with air quality improvements can deliver substantial co-benefits through reductions in greenhouse gas emissions and air pollutant concentrations. Mitigation strategies range from sufficiency to technology-driven transitions, yet linked co-benefits remain poorly understood. This study evaluates PM 2.5 and NO 2 exposure changes and associated co-benefits using France’s energy-transition scenarios. Methods Emission projections were incorporated to the CHIMERE chemistry-transport model to estimate PM 2.5 and NO 2 concentrations for 2030 and 2050. Health impacts were assessed using disease-specific cessation-lag assumptions relative to 2019, covering premature mortality, morbidity, DALYs, and economic benefits across nine outcomes (hypertension, lung cancer, ischaemic heart disease, stroke, COPD, type-2 diabetes, acute lower respiratory infections, and asthma in children and adults). Findings Population exposure in continental France is projected to decline by 23% and 45% for PM 2.5 and NO 2 by 2030, rising to 40% and 70% by 2050. Health gains are substantial and broadly consistent across all four scenarios, with modest differences between sufficiency-oriented and technology-driven pathways. Under delayed-impact assumptions, which accounts for the latency between exposure reduction and health response, avoided premature deaths reached 8,800-9,300 for PM 2.5 and 11,000-12,800 for NO 2 in 2030, rising to 21,300-22,100 and 24,500-26,200 by 2050. Avoided morbidity cases grew from 51,100–55,200 in 2030 to 84,000-87,800 by 2050, with total DALYs averted increasing from 278,000-310,000 to 427,000-450,000 over the same period. Economic benefits scaled accordingly, direct medical cost savings reached €1.0-1.1 billion/year by 2050, with intangible cost savings of €41-43 billion with PM 2.5 and €36-39 billion with NO 2 reductions. Conclusion Net-zero transition delivers substantial, progressive health and economic co-benefits that are robust across diverse policy pathways. Rather than sectoral composition, commitment to decarbonisation itself drives air quality improvements and population health gains. These findings support integrating co-benefits into climate policy frameworks to strengthen the evidence base for ambitious mitigation action. Highlights Net-zero policies can deliver large air-quality co-benefits; here, chemistry-transport modeling coupled with emission projections quantifies these benefits across four contrasting French decarbonisation pathways for 2030 and 2050. Health and economic co-benefits are large and robust across all four contrasting scenarios, with modest differences between sufficiency-oriented and technology-driven pathways. By 2050, PM 2.5 and NO 2 concentrations decline by 38-40% and 70-75%, averting 20,000-22,000 and 24,500-26,200 attributable premature deaths annually. Avoided morbidity reaches 84,000-87,800 cases/year and DALYs averted reach 427,000-450,000/year in 2050, growing substantially from 2030 estimates. Monetization of health impacts results in, direct medical savings of €1 billion/year in 2050 and intangible cost savings of €43 billion (PM 2.5 ) and €38 billion (NO 2 ) per year.

Ozone (O3) and nitrogen dioxide (NO2) are two common gaseous pollutants that both possess oxidizing properties with consequences for human health and have an inextricable chemical relationship that could have distinct public health impacts when considered in combination. We examined the short-term associations of the combined oxidative capacity of O3 and NO2 (represented by Oxwt, the average of O3 and NO2 concentrations weighted by their standard electrode potential) with total, cardiovascular and respiratory mortality in 380 cities across 23 countries or regions between 1985 and 2020. Over 2 days (LAG01), a 10-ppb increase in Oxwt concentration was associated with an increase of 0.82% (95% confidence interval (CI): 0.55%, 1.10%) in total mortality, 1.09% (95% CI: 0.83%, 1.35%) in cardiovascular mortality and 0.88% (95% CI: 0.31%, 1.45%) in respiratory mortality. We also observed variations in this association by geographic region and study period. More deaths were attributable to Oxwt than to either O3 or NO2 but fewer than the sum of the two. Thus, Oxwt might be a valuable indicator for use in public health efforts to capture the combined effects of O3 and NO2.

BACKGROUND:Ambient PM10 is associated with mortality; however, potential changes in this association over time and the factors explaining such changes are unclear. Therefore, we aimed to examine whether mortality risk associated with PM10 has changed from 1979 to 2019 and whether changes in socioeconomic or environmental conditions can explain any temporal variation in the association between PM10 and mortality. METHODS:We applied an extended two-stage time-series design to assess temporal change in the association between PM10 and all-cause mortality across 143 cities in 26 countries from 1979 to 2019. In the first stage, city-specific and time-specific associations between PM10 and mortality were estimated using quasi-Poisson regression after each city time series was divided into non-overlapping 3-year segments. In the second stage, these estimates were pooled by use of longitudinal random-effects meta-regression with calendar year as a predictor. We further investigated whether selected socioeconomic and environmental factors explained observed temporal trends by including these variables in the second-stage model. FINDINGS:Totally, 23·2 million deaths were analysed. The overall association between PM10 and mortality had increased from 1979 to 2019, indicating a stronger association at a given PM10 concentration over time. A 10 μg/m3 increase in daily PM10 was associated with a 0·23% increase in all-cause mortality in 1979 (95% CI 0·05-0·41), and this association increased to 0·51% in 2019 (0·36-0·65). Temporal patterns in the PM10-mortality association varied across cities and were positively associated with population ageing over time and negatively associated with annual mean PM10 concentrations. INTERPRETATION:The findings of this study suggest that the effect of a given increment of PM10 on mortality has increased over time. Applying historical risk estimates could underestimate the current health burden. Continuous updating of evidence on the health impacts of air pollution is essential to ensure accurate and valid estimates. FUNDING:Wellcome Trust.

Minimum mortality temperature (MMT) is an important feature of temperature-mortality relationship, defined as the temperature at which mortality risk is lowest. Although numerous studies have estimated MMT for all-cause mortality, few have explored differences by age or cause of death. We analyzed daily mean temperature and mortality data from 667 communities across 39 countries. Mortality was classified by age and cause of death (cardiovascular, respiratory, or non-cardiorespiratory). A two-stage meta-analytic approach was applied to estimate the MMT and its corresponding percentile (MMTP) by age and cause of death. In the overall population, MMT was the highest for cardiovascular mortality (22.1 °C, 95% CI: 20.9-23.4 °C), whereas respiratory and non-cardiorespiratory causes were 0.87 °C and 0.66 °C lower, respectively, than that for cardiovascular causes. Similar patterns were observed for MMTP, which was highest for cardiovascular mortality (75%, 95% CI: 73-78%) and lower by 5% and 4% for respiratory and non-cardiorespiratory causes, respectively. MMT increased with age for cardiovascular (0.19 °C per 10 years, 95% CI: 0.14-0.23) and non-cardiorespiratory causes (0.13 °C per 10 years, 95% CI: 0.09-0.16). These patterns were generally consistent across geographical regions. Overall, both MMT and MMTP differed by cause of death and age, indicating that the optimal temperature varies across population subgroups.

Increased ambient heat exposure poses a health risk to pregnant women, which may be amplified by environmental and social determinants, but these interactions have been insufficiently characterized. We examined critical windows for the associations between heat exposure during pregnancy and fetal growth and investigated the role of air pollution, vegetation, and social stressors in these associations. Weekly exposure to ambient temperature and air pollutants (PM2.5, NO2, O3) from highly resolved spatiotemporal models, vegetation, and contextual deprivation were estimated for 20,904 French women (2002-2017). Distributed lag nonlinear models evaluated associations between heat and term birth weight (tBW), tBW Z-score, and small-for-gestational-age. We further adjusted our models for air pollutants and stratified on vegetation and social determinants. Heat exposure during the first two trimesters was associated with reduced fetal growth. A mean temperature of 21.6 °C (95th percentile vs median 13.6 °C) during weeks 2-15 was associated with a reduced tBW (-199 g [95% CI: -268; -131]). These associations differed after adjusting for O3 exposure. Trends for stronger associations were observed in women with low vegetation exposure, low social position, and high contextual deprivation. This study highlights how heat stress during early pregnancy could reduce birth weight.

Heat exposure in pregnancy has been associated with mother-child health. However, characterization of exposure to heat in pregnant women and its associated factors, such as air pollution, vegetation or social stressors, is lacking. We aimed to describe heat exposure according to air pollution and vegetation co-exposures, individual social position and socio-economic context of residence among French pregnant women. We studied 12,235 pregnant women from four mother-child cohorts. Exposure to heat (intensity, duration, severity), particulate matter, nitrogen dioxide (NO2), ozone (O3), and vegetation during summer were estimated at the women's residences. Socio-economic context of residence was assessed using the European Deprivation Index (EDI). Cumulative overexposure to heat, air pollution and vegetation were estimated according to reference values. Three profiles of heat exposure, multi-exposure and individual social position, were created using multivariate analysis and unsupervised clustering. Associations of the profiles of heat exposure and multi-exposure with air pollution, vegetation, individual social position and EDI were described using Wilcoxon tests and polytomous regressions. About one-third of pregnant women had a high heat exposure profile combining intense, severe and durable exposure. Depending on the location and year of pregnancy, 27-88% of women were overexposed to heat, air pollution and lack of vegetation. The relationships between profiles of heat and multi-exposure with air pollution, vegetation and individual social position and socioeconomic context of residence depended on the geographical and temporal context. No clear differential exposure pattern across social strata was found. Co-exposure to heat, air pollution and lack of vegetation is common among French pregnant women. Protective measures against summer heat would apply to all pregnant women, as heat exposure represents a universal risk, regardless of socioeconomic status. This research supports future epidemiological studies on combined effects of heat and co-exposures on pregnancy outcomes.

BACKGROUND:Heat exposure poses a substantial public health threat. Increasing greenness has been suggested as a mitigation strategy due to its cooling effect and potential to modify the heat-mortality association. This study aimed to comprehensively estimate the effects of increased greenness on heat-related deaths. METHODS:We applied a multistage meta-analytical approach to estimate the potential reduction in global heat-related deaths by increasing greenness in the warm season in 2000-19 in 11 534 urban areas. We used the enhanced vegetation index (EVI) to indicate greenness and a random forest model to predict daily temperatures in counterfactual EVI scenarios. In the factual EVI scenarios, daily mortality and weather variables from 830 locations in 53 countries were extracted from the Multi-Country Multi-City Collaborative Research Network and used to assess heat-mortality associations. These associations were then extrapolated to each urban area under both factual and counterfactual EVI scenarios based on meta-regression models. FINDINGS:We estimated that EVI increased by 10% would decrease the global population-weighted warm-season mean temperature by 0·08°C, EVI increased by 20% would decrease temperature by 0·14°C, and EVI increased by 30% would decrease temperature by 0·19°C. In the factual scenario, 3 153 225 (2·48%) of 127 179 341 total deaths could be attributed to heat exposure. The attributable fraction of heat-related deaths (as a fraction of total deaths) in 2000-19 would decrease by 0·67 (95% empirical CI 0·53-0·82) percentage points in the 10% scenario, 0·80 (0·63-0·97) percentage points in the 20% scenario, and 0·91 (0·72-1·10) percentage points in the 30% scenario, compared with the factual scenario. South Europe was modelled to have the largest decrease in attributable fraction of heat-related mortality. INTERPRETATION:This modelling study suggests that increased greenness could substantially reduce the heat-related mortality burden. Preserving and expanding greenness might be potential strategies to lower ambient temperature and reduce the health impacts of heat exposure. FUNDING:Australian Research Council and Australian National Health and Medical Research Council.

BACKGROUND:The rise in hot nights over recent decades and projections of further increases due to climate change underscores the critical need to understand their impact. This knowledge is essential for shaping public health strategies and guiding adaptation efforts. Despite their significance, research on the implications of hot nights remains limited. OBJECTIVE:This study estimated the association between hot-night excess (the sum of excess heat during the nighttime above a threshold) and duration (the percent of nighttime with a positive excess) based on hourly ambient temperatures and daily mortality in the warm season over multiple locations worldwide. METHODS:We fitted time series regression models to mortality in 178 locations across 44 countries using a distributed lag non-linear model over lags of 0-3 days, controlling for daily maximum temperature and daily mean absolute humidity. Next, we used a multivariate meta-regression model to pool results and estimated attributable burdens. RESULTS:We found a positive, increasing mortality risk with hot-night excess and duration. Assuming 0 as a reference, the pooled relative risks of death associated with extreme excess and duration, defined as the 90th percentile in each index, were both similar at 1.026 (95 % CI, 1.017; 1.036) and 1.026 (95 % CI, 1.013; 1.040). The overall estimated attributable fractions were also observed to be closely similar at 0.60 % (95 % CI, 0.09; 1.10 %) and 0.62 % (95 % CI, 0.00; 1.23 %), respectively. DISCUSSION:This study provides new evidence that hot nights have a specific contribution to heat-related mortality risk. Modeling thermal characteristics' sub-hourly impact on mortality during the night could improve decision-making for long-term adaptions and preventive public health strategies.

Heat-health warning systems and action plans, referred to as heat prevention plans (HPPs), are key public health interventions aimed at reducing heat-related mortality. Despite their importance, prior assessments of their effectiveness have yielded inconsistent results. The objective of this study is to systematically assess the effectiveness of HPPs in reducing heat-related mortality risk across Europe. We analysed daily mortality and mean temperature data from 102 locations in 14 European countries between 1990 and 2019. Using data from national experts, we identified the year of HPP implementation and categorised their development class. A three-stage analysis was conducted: (1) quasi-Poisson time series models were used to estimate location-specific warm-season exposure-response functions in 3 year subperiods; (2) mixed-effect meta-regression models with multilevel longitudinal structures were employed to quantify changes in pooled exposure-response functions due to HPP implementation, adjusted for long-term trends in heat-related mortality risks; and (3) the heat-related excess mortality due to HPP was calculated by comparing factual (with HPP) and counterfactual (without HPP) scenarios. Estimates are reported by country, region, and HPP class. HPP implementation was associated with a 25.2% [95% CI: 19.8% to 31.9%] reduction in excess deaths attributable to extreme heat, corresponding to 1.8 [95% CI: 1.3–2.4] avoided deaths annually per 100 000 inhabitants. This equates to an estimated 14 551 [95% CI: 10 118–19 072] total deaths avoided across all study locations following HPP implementation. No significant differences in HPP effectiveness were observed by European region or HPP class. Our findings provide robust evidence that HPPs substantially reduce heat-related mortality across Europe, accounting for temporal changes and geographical differences in risks. These results emphasise the importance of monitoring and evaluating HPPs to enhance adaptation to a warming climate.

BACKGROUND:To adapt the health system to climate change, it is important to understand how heat affects healthcare use. This study examines the impact of heat on emergency department (ED) visits and hospital admissions (HA) by age (15-64, 65 and over), sex, type of urban environment and social deprivation, in the Paris region (France). METHOD:Daily ED visits and HA were collected for the 527 postal codes and 1,287 municipalities, for cardiovascular, respiratory, renal, heat-related causes, by age and sex, from 2010 to 2019. Daily mean temperatures were estimated for each postal code and municipality using 1.25 km gridded data. Time-series analyses using non-linear distributed lag models were used. RESULTS:Heat was associated with an increase in ED visits and HA for heat-related causes, respiratory causes and renal causes in all areas, age groups and sex. Around 27,000 ED visits and 4,800 HA were attributable to heat between 2010 and 2019 in the Paris region, including around 15,000 ED visits for malaise, and 3,100 HA for respiratory causes. DISCUSSION:The results highlight that the effects of heat are numerous, and are not uniform depending on the causes and health indicators studied. They call for a stronger action to prevent the impacts of heat on morbidity.

Increasing urban vegetation coverage is associated with improved human health and well-being, reduced environmental impact of cities and enhanced urban resilience to climate change. To support evidence-based urban planning, this study quantifies the mortality benefits, equity implications and cost-benefit ratio of several scenarios of green space development in Paris by 2040, including the replacement of car-dedicated surfaces with green spaces and a best-case scenario. This quantitative health impact assessment is based on estimated changes in the Normalized Difference Vegetation Index (NDVI), obtained through the estimation of the dynamic effects over time using a Difference-in-Differences approach based on previous public greening interventions, and on an exposure-response relationship linking NDVI and all-cause mortality. It was conducted at the sub-municipal level (IRIS) and incorporates a social deprivation index to assess health equity implications. Vegetation costs are drawn from a previous French study estimating urban soil restoration prices. Replacing surplus on-street parking and 20% of street space with vegetation could reduce all-cause mortality by around 0.8%, while reaching 15% of vegetation coverage in each IRIS could prevent around 3% of deaths yearly in Paris as early as 2040. For all scenarios, these benefits were approximatively equally distributed across deprivation levels. Predicted monetised health benefits outweigh intervention costs by 2035, with further impacts representing net gain. In conclusion, greening interventions targeting car-dedicated space in Paris would equitably improve health while supporting more sustainable and resilient cities. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study did not receive any funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present work are contained in the manuscript

Countless heat records were broken in recent years, leading to thousands of heat-related deaths. This raises the question of how much worse heat-related mortality could become in coming years if a potential worst-case heatwave lasts for several weeks or reaches unprecedented intensity. Here, we develop impact storylines for worst-case heatwaves and associated heat-related mortality in France, Germany, and Switzerland. We compare several physical climate storyline approaches to quantify plausible extreme heatwaves and combine these with empirical heat-mortality relationships. The storylines are based on (a) using a Single-Model Initial Condition Large Ensemble (SMILE), (b) ensemble boosting, and by looking for the most extreme events (UNSEEN approach) in the initialized (c) 45-day sub-seasonal re-forecast and (d) 7-months seasonal forecasting system using the ECMWF Integrated Forecast System (IFS).In all four approaches we find physically consistent week-long heatwaves possible in the climate of 2020 that exceed the observed 7-day record temperatures by more than 5°C and associated mortality impacts exceeding the observed maximum by 30-90%. Even more severe consequences would arise from possible five-week heat periods of unprecedented intensity, which would lead to more than a doubling of impacts. Developing these impact storylines can inform the stress-testing of socio-economic systems for preparing appropriate emergency response capacities.

Background:The presence of benzene, toluene, ethylbenzene, and xylene isomers (BTEX) in the environment is of increasing concern due to their toxicity and ubiquity. Although the adverse health effects of BTEX exposure have been documented, robust epidemiological evidence from large-scale, multicountry studies using advanced exposure assessment methodologies remains scarce. We aimed to assess the association of short-term ambient exposure to individual BTEX components and their mixture with daily total, cardiovascular, and respiratory mortality on a global scale. Methods:Daily data on mortality, meteorological factors, and air pollution were collected from 757 locations across 46 countries or regions. Data on individual chemicals (ie, benzene, toluene, xylenes [summation of ethylbenzene, m-xylene, p-xylene, and o-xylene]) and the aggregate mixture (ie, BTEX) were estimated using a chemistry-climate model. We examined the short-term associations of each individual chemical as well as the BTEX mixture with daily total, cardiovascular, and respiratory mortality in a multicountry framework. Using a two-stage time-series design, we first applied generalised additive models with a quasi-Poisson distribution to obtain location-specific associations, which were subsequently pooled using random-effects meta-analysis. Two-pollutant models were used to assess the independent effects of BTEX after adjusting for co-pollutants (PM2⋅5, PM10, nitrogen dioxide, sulphur dioxide, ozone, and carbon monoxide). Additionally, we assessed the overall exposure-response curves with spline terms. Findings:An IQR increment of BTEX concentration on lag 0-2 days (3-day moving average of the present day and the previous 2 days) was associated with increases of 0⋅57% (95% CI 0⋅49-0⋅65), 0⋅42% (0⋅30-0⋅54), and 0⋅68% (0⋅50-0⋅86) in total, cardiovascular, and respiratory mortality, respectively. The corresponding effect estimates for an IQR increment in individual chemicals (benzene, toluene, and xylenes) were 0⋅38-0⋅61%, 0⋅44-0⋅70%, and 0⋅41-0⋅65%, respectively. The associations remained significant after adjusting for co-pollutants, with a general decline in magnitude, except for a slight increase after adjustment for ozone. The shape of the exposure-response curves for all pollutants and causes of death was almost linear, with steeper slopes at low concentrations and no discernible thresholds. Interpretation:This global study provides novel evidence linking short-term exposure to ambient BTEX, both individually and as a mixture, with increased daily total, cardiovascular, and respiratory mortality. Our findings underscore the need for comprehensive air pollution mitigation policies, including stringent controls on BTEX emissions, to protect public health. Funding:Noncommunicable Chronic Diseases-National Science and Technology Major Project, National Natural Science Foundation of China, Shanghai Municipal Science and Technology Major Project, Shanghai B&R Joint Laboratory Project, and Shanghai International Science and Technology Partnership Project.

Developing indicators to monitor spatial and temporal trends in the health effects of climate change is crucial to encouraging adaptation. Heat is one of the most studied climate-related health issues, but its impact is still little known to decision-makers. We propose an approach for producing annual estimates of heat-related mortality, as an indicator to support adaptation policies. A first step was to develop temperature-mortality relationships for each of the 96 metropolitan French departments, for summers (June- September) 2014-2022. Several approaches were tested to control for a possible influence of the COVID-19 pandemic since 2020. Those models were then used to compute the annual mortality attributable to heat for 2014-2023. Heat-related risks tended to be slighly higher after the pandemic ; an increase from 19.8°C to 28.5°C was associated with a relative risk of 1.25 [CI 95% 1.21 :1.30] in 2004-2019, and 1.31 [1.24 :1.38] in 2020-2022. Between 2014 and 2023, 37,825 deaths [IC95% 34,273 : 40,483] were attributable to heat. The largest impacts are observed in 2022 (6,969 [6,277 : 7,445]), 2023 (5 167 [4 587 ; 5 551]), and 2019 (4,441 [4,086 : 4,717]). The 2014-2022 temperature-mortality relationships will be used to compute the heat-related mortality for the coming year. A regular update of the relationships is planned. This indicator documents the mortality impact of heat during the summer and during extreme heat waves. It shows that the impact is increasing, despite major prevention efforts. This call for a more ambitious, transformative adaptation to climate change.

Background:The minimum mortality temperature (MMT) or MMT percentile (MMTP) is an indicator of population susceptibility to nonoptimum temperatures. MMT and MMTP change over time; however, the changing directions show region-wide heterogeneity. We examined the heterogeneity of temporal changes in MMT and MMTP across multiple communities and in multiple countries. Methods:Daily time-series data for mortality and ambient mean temperature for 699 communities in 34 countries spanning 1986-2015 were analyzed using a two-stage meta-analysis. First, a quasi-Poisson regression was employed to estimate MMT and MMTP for each community during the designated subperiods. Second, we pooled the community-specific temporally varying estimates using mixed-effects meta-regressions to examine temporal changes in MMT and MMTP in the entire study population, as well as by climate zone, geographical region, and country. Results:Temporal increases in MMT and MMTP from 19.5 °C (17.9, 21.1) to 20.3 °C (18.5, 22.0) and from the 74.5 (68.3, 80.6) to 75.0 (71.0, 78.9) percentiles in the entire population were found, respectively. Temporal change was significantly heterogeneous across geographical regions (P < 0.001). Temporal increases in MMT were observed in East Asia (linear slope [LS] = 0.91, P = 0.02) and South-East Asia (LS = 0.62, P = 0.05), whereas a temporal decrease in MMT was observed in South Europe (LS = -0.46, P = 0.05). MMTP decreased temporally in North Europe (LS = -3.45, P = 0.02) and South Europe (LS = -2.86, P = 0.05). Conclusions:The temporal change in MMT or MMTP was largely heterogeneous. Population susceptibility in terms of optimum temperature may have changed under a warming climate, albeit with large region-dependent variations.

The year 2023 was the warmest year in the 174-year global instrumental record. The year was also marked by a series of climate-related extreme events, including heat waves, storms, and wildfires that caused widespread economic and health impacts. The 28th Conference of the Parties of the United Nations Framework Convention on Climate Change called for transitioning away from fossil fuels and accelerating action in this critical decade. All countries must move rapidly toward net zero emissions and scale up their action to ensure achievement of the Paris climate goals-viz., limiting the global temperature increase from preindustrial levels to well below 2 °C and pursuing efforts to keep it below 1.5 °C. There is growing concern about whether the goal of limiting global warming to 1.5 °C is still achievable. We believe that it is still possible to limit warming to 1.5 °C if we take seven essential actions so human health and survival can be safeguarded: scaling up the energy transition to achieve carbon neutrality before the middle of this century; rapidly phasing out the construction of new fossil fuel exploration and infrastructure; enforcing an international carbon price; tightening emission targets across both the global north and south; promoting and adopting low-consumption lifestyle as the social norm; engaging in transformative change to simultaneously act on climate, biodiversity, equity, human health, and well-being; and boosting collective efforts and strengthening international cooperation.

Background:We quantify the mortality burden and economic loss attributable to nonoptimal temperatures for cold and heat in the Central and South American countries in the Multi-City Multi-Country (MCC) Collaborative Research Network. Methods:We collected data for 66 locations from 13 countries in Central and South America to estimate location-specific temperature-mortality associations using time-series regression with distributed lag nonlinear models. We calculated the attributable deaths for cold and heat as the 2.5th and 97.5th temperature percentiles, above and below the minimum mortality temperature, and used the value of a life year to estimate the economic loss of delayed deaths. Results:The mortality impact of cold varied widely by country, from 9.64% in Uruguay to 0.22% in Costa Rica. The heat-attributable fraction for mortality ranged from 1.41% in Paraguay to 0.01% in Ecuador. Locations in arid and temperate climatic zones showed higher cold-related mortality (5.10% and 5.29%, respectively) than those in tropical climates (1.71%). Arid and temperate climatic zones saw lower heat-attributable fractions (0.69% and 0.58%) than arid climatic zones (0.92%). Exposure to cold led to an annual economic loss of $0.6 million in Costa Rica to $472.2 million in Argentina. In comparison, heat resulted in economic losses of $0.05 million in Ecuador to $90.6 million in Brazil. Conclusion:Most of the mortality burden for Central and South American countries is caused by cold compared to heat, generating annual economic losses of $2.1 billion and $290.7 million, respectively. Public health policies and adaptation measures in the region should account for the health effects associated with nonoptimal temperatures.