Heat-related cardiorespiratory mortality: Effect modification by air pollution across 482 cities from 24 countries

BACKGROUND

Evidence on the potential interactive effects of heat and ambient air pollution on cause-specific mortality is inconclusive and limited to selected locations.

OBJECTIVES

We investigated the effects of heat on cardiovascular and respiratory mortality and its modification by air pollution during summer months (six consecutive hottest months) in 482 locations across 24 countries.

METHODS

Location-specific daily death counts and exposure data (e.g., particulate matter with diameters ≤ 2.5 µm [PM2.5]) were obtained from 2000 to 2018. We used location-specific confounder-adjusted Quasi-Poisson regression with a tensor product between air temperature and the air pollutant. We extracted heat effects at low, medium, and high levels of pollutants, defined as the 5th, 50th, and 95th percentile of the location-specific pollutant concentrations. Country-specific and overall estimates were derived using a random-effects multilevel meta-analytical model.

RESULTS

Heat was associated with increased cardiorespiratory mortality. Moreover, the heat effects were modified by elevated levels of all air pollutants in most locations, with stronger effects for respiratory than cardiovascular mortality. For example, the percent increase in respiratory mortality per increase in the 2-day average summer temperature from the 75th to the 99th percentile was 7.7% (95% Confidence Interval [CI] 7.6-7.7), 11.3% (95%CI 11.2-11.3), and 14.3% (95% CI 14.1-14.5) at low, medium, and high levels of PM2.5, respectively. Similarly, cardiovascular mortality increased by 1.6 (95%CI 1.5-1.6), 5.1 (95%CI 5.1-5.2), and 8.7 (95%CI 8.7-8.8) at low, medium, and high levels of O3, respectively.

DISCUSSION

We observed considerable modification of the heat effects on cardiovascular and respiratory mortality by elevated levels of air pollutants. Therefore, mitigation measures following the new WHO Air Quality Guidelines are crucial to enhance better health and promote sustainable development.

Excess mortality attributed to heat and cold: a health impact assessment study in 854 cities in Europe

BACKGROUND

Heat and cold are established environmental risk factors for human health. However, mapping the related health burden is a difficult task due to the complexity of the associations and the differences in vulnerability and demographic distributions. In this study, we did a comprehensive mortality impact assessment due to heat and cold in European urban areas, considering geographical differences and age-specific risks.

METHODS

We included urban areas across Europe between Jan 1, 2000, and Dec 12, 2019, using the Urban Audit dataset of Eurostat and adults aged 20 years and older living in these areas. Data were extracted from Eurostat, the Multi-country Multi-city Collaborative Research Network, Moderate Resolution Imaging Spectroradiometer, and Copernicus. We applied a three-stage method to estimate risks of temperature continuously across the age and space dimensions, identifying patterns of vulnerability on the basis of city-specific characteristics and demographic structures. These risks were used to derive minimum mortality temperatures and related percentiles and raw and standardised excess mortality rates for heat and cold aggregated at various geographical levels.

FINDINGS

Across the 854 urban areas in Europe, we estimated an annual excess of 203 620 (empirical 95% CI 180 882-224 613) deaths attributed to cold and 20 173 (17 261-22 934) attributed to heat. These corresponded to age-standardised rates of 129 (empirical 95% CI 114-142) and 13 (11-14) deaths per 100 000 person-years. Results differed across Europe and age groups, with the highest effects in eastern European cities for both cold and heat.

INTERPRETATION

Maps of mortality risks and excess deaths indicate geographical differences, such as a north-south gradient and increased vulnerability in eastern Europe, as well as local variations due to urban characteristics. The modelling framework and results are crucial for the design of national and local health and climate policies and for projecting the effects of cold and heat under future climatic and socioeconomic scenarios.

FUNDING

Medical Research Council of UK, the Natural Environment Research Council UK, the EU's Horizon 2020, and the EU's Joint Research Center.

Implementation of adaptation to climate change in public health in Europe: qualitative thematic analysis

BACKGROUND

Increasingly, climate change policies are emerging across Europe. Policies addressing adaptation (adjusting the effects of climate change on public health) are being implemented after the COVID-19 pandemic. This study aims to identify issues in climate adaptation implementation for public health and understand the health implications from responses after COVID-19.

METHODS

Key informant interviews were undertaken with decision makers in international, national, and local governments across 20 European countries (Norway, England, Cyprus, Spain, Ireland, Finland, Lithuania, Belgium, the Netherlands, Sweden, Latvia, Italy, Estonia, Austria, Croatia, France, Germany, Hungary, Denmark, and Scotland). A WHO stakeholder analytical framework was followed for developing the interview themes. Participants were recruited if based in European governments, working in public or environmental health, and involved in climate adaptation policy. Participants were recruited through known networks and geographical coverage was obtained (eight per European region). An interview schedule with key themes (barriers, public health agenda, levers, networks, evidence needs, and COVID-19 recovery) was used. Interviews were conducted online, recorded, transcribed, and analysed through Nvivo.

FINDINGS

32 interviews were completed between June and October, 2021; four international stakeholders, five national-level decision makers, 23 city-level decision makers or network representatives. Most reported inadequate resources for health adaptation implementation (funding, training, and personnel) and the marginal role of health in climate adaptation policy. A key reported challenge was limited departmental cross-collaboration across governance levels, because city-level stakeholders were less aware of the public health role in climate change policy. COVID-19 recovery strategies were not perceived as opportunistic for future adaptation. However, several respondents identified benefits for health system resilience, for example improved emergency planning and disaster management.

INTERPRETATION

Across Europe, there is varied progress in the implementation of climate change and health adaptation. Providing appropriate resource, inter-departmental collaboration, knowledge mobilisation, and multi-level governance support will facilitate climate and health policy implementation. Overcoming these barriers and learning from COVID-19 through strengthened emergency planning and responses to climate events can strengthen UK public health system resilience and beyond.

FUNDING

This project has received part-funding from the Enhancing Belmont Research Action to support EU policy making on climate change and health project, which is part of the EU's Horizon 2020 research and innovation programme (grant agreement number 101003966). The research was part-funded by the National Institute for Health Research Health Protection Research Unit in Environmental Change and Health at the London School of Hygiene and Tropical Medicine in partnership with Public Health England, the Met Office, and University College London (grant number PHSEZT6210). The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR, the Department of Health and Social Care or PHE.

Heat-health action planning in the WHO European Region: Status and policy implications

Adverse health effects from extreme heat remain a major risk, especially in a changing climate. Several European countries have implemented heat health action plans (HHAPs) to prevent ill health and excess mortality from heat. This paper assesses the state of implementation of HHAPs in the WHO European Region and discusses barriers and successes since the early 2000s. The results are based on a web-based survey among 53 member states on the current national and federal HHAPs in place. Guided by the eight core elements of HHAPs as outlined by the WHO Regional Office for Europe guidance from 2008, we analyzed which elements were fully or partially implemented and which areas of improvement countries identified. HHAP adaptations to account for COVID-19 were sought via literature search and expert consultations. 27 member states provided information, of which 17 countries reported having a HHAP. Five out of eight core elements, namely agreement on a lead body, accurate and timely alert systems, heat-related health information plans, strategies to reduce health exposure, and care for vulnerable groups, were at least partially implemented in all 17 plans. Alert systems were implemented most often at 94%. The least often implemented items were real-time surveillance, long-term urban planning, and preparedness of health and social systems. Five countries had published COVID-19 guidance online. Our findings suggest a progressive improvement in the development and rollout of HHAPs overall and awareness of vulnerable population groups in WHO/Europe, while integration of HHAPs into long-term climate change and health planning remains a challenge.

Global, regional, and national burden of mortality associated with short-term temperature variability from 2000-19: a three-stage modelling study

BACKGROUND

Increased mortality risk is associated with short-term temperature variability. However, to our knowledge, there has been no comprehensive assessment of the temperature variability-related mortality burden worldwide. In this study, using data from the MCC Collaborative Research Network, we first explored the association between temperature variability and mortality across 43 countries or regions. Then, to provide a more comprehensive picture of the global burden of mortality associated with temperature variability, global gridded temperature data with a resolution of 0·5° × 0·5° were used to assess the temperature variability-related mortality burden at the global, regional, and national levels. Furthermore, temporal trends in temperature variability-related mortality burden were also explored from 2000-19.

METHODS

In this modelling study, we applied a three-stage meta-analytical approach to assess the global temperature variability-related mortality burden at a spatial resolution of 0·5° × 0·5° from 2000-19. Temperature variability was calculated as the SD of the average of the same and previous days' minimum and maximum temperatures. We first obtained location-specific temperature variability related-mortality associations based on a daily time series of 750 locations from the Multi-country Multi-city Collaborative Research Network. We subsequently constructed a multivariable meta-regression model with five predictors to estimate grid-specific temperature variability related-mortality associations across the globe. Finally, percentage excess in mortality and excess mortality rate were calculated to quantify the temperature variability-related mortality burden and to further explore its temporal trend over two decades.

FINDINGS

An increasing trend in temperature variability was identified at the global level from 2000 to 2019. Globally, 1 753 392 deaths (95% CI 1 159 901-2 357 718) were associated with temperature variability per year, accounting for 3·4% (2·2-4·6) of all deaths. Most of Asia, Australia, and New Zealand were observed to have a higher percentage excess in mortality than the global mean. Globally, the percentage excess in mortality increased by about 4·6% (3·7-5·3) per decade. The largest increase occurred in Australia and New Zealand (7·3%, 95% CI 4·3-10·4), followed by Europe (4·4%, 2·2-5·6) and Africa (3·3, 1·9-4·6).

INTERPRETATION

Globally, a substantial mortality burden was associated with temperature variability, showing geographical heterogeneity and a slightly increasing temporal trend. Our findings could assist in raising public awareness and improving the understanding of the health impacts of temperature variability.

FUNDING

Australian Research Council, Australian National Health & Medical Research Council.

Climate and health adaptation: evidence needs for policy (Stakeholder mapping in Europe)

Introduction

In recent years, both the EU Commission and the Belmont Forum have funded projects focusing on health and climate change with the aim of expanding research and evidence and improving intersectoral cooperation. The EU-funded ENBEL project is developing tools to streamline climate and health research to support policies and strategies and improve response and resilience.

Methods

Within ENBEL a stakeholder analysis is being carried out for Europe to identify key decision makers involved in climate change and health adaptation, understand interlinkages and identify areas for action to promote collaboration and uptake. Semi-structured interviews with key institutions and stakeholders at different levels (International, European, national and local) will help identify key evidence needs and research gaps and findings will be used to define knowledge tools and policy briefs to enhance adaptation. Furthermore, current policies on adaptation in Europe and how health issues are addressed, especially taking into account the Next Generation EU (NGEU) funding in support of COVID-19 recovery as well as Green Deal and Climate Action, will be reviewed to ensure ENBEL products fit the EU policy agenda.

Conclusions

ENBEL offers an opportunity to produce targeted research syntheses for decision makers as well an ensuring health becomes a key aspect in climate change policy decision making. The ENBEL project will engage with key decision makers involved in climate change and health adaptation across Europe, providing knowledge, understanding interlinkages and identifying areas for action to promote climate policies that enhance health benefits.

Global, regional, and national burden of mortality associated with non-optimal ambient temperatures from 2000 to 2019: a three-stage modelling study

BACKGROUND

Exposure to cold or hot temperatures is associated with premature deaths. We aimed to evaluate the global, regional, and national mortality burden associated with non-optimal ambient temperatures.

METHODS

In this modelling study, we collected time-series data on mortality and ambient temperatures from 750 locations in 43 countries and five meta-predictors at a grid size of 0·5° × 0·5° across the globe. A three-stage analysis strategy was used. First, the temperature-mortality association was fitted for each location by use of a time-series regression. Second, a multivariate meta-regression model was built between location-specific estimates and meta-predictors. Finally, the grid-specific temperature-mortality association between 2000 and 2019 was predicted by use of the fitted meta-regression and the grid-specific meta-predictors. Excess deaths due to non-optimal temperatures, the ratio between annual excess deaths and all deaths of a year (the excess death ratio), and the death rate per 100 000 residents were then calculated for each grid across the world. Grids were divided according to regional groupings of the UN Statistics Division.

FINDINGS

Globally, 5 083 173 deaths (95% empirical CI [eCI] 4 087 967-5 965 520) were associated with non-optimal temperatures per year, accounting for 9·43% (95% eCI 7·58-11·07) of all deaths (8·52% [6·19-10·47] were cold-related and 0·91% [0·56-1·36] were heat-related). There were 74 temperature-related excess deaths per 100 000 residents (95% eCI 60-87). The mortality burden varied geographically. Of all excess deaths, 2 617 322 (51·49%) occurred in Asia. Eastern Europe had the highest heat-related excess death rate and Sub-Saharan Africa had the highest cold-related excess death rate. From 2000-03 to 2016-19, the global cold-related excess death ratio changed by -0·51 percentage points (95% eCI -0·61 to -0·42) and the global heat-related excess death ratio increased by 0·21 percentage points (0·13-0·31), leading to a net reduction in the overall ratio. The largest decline in overall excess death ratio occurred in South-eastern Asia, whereas excess death ratio fluctuated in Southern Asia and Europe.

INTERPRETATION

Non-optimal temperatures are associated with a substantial mortality burden, which varies spatiotemporally. Our findings will benefit international, national, and local communities in developing preparedness and prevention strategies to reduce weather-related impacts immediately and under climate change scenarios.

FUNDING

Australian Research Council and the Australian National Health and Medical Research Council.

Effects of Hot Nights on Mortality in Southern Europe

BACKGROUND

There is strong evidence concerning the impact of heat stress on mortality, particularly from high temperatures. However, few studies to our knowledge emphasize the importance of hot nights, which may prevent necessary nocturnal rest.

OBJECTIVES

In this study, we use hot-night duration and excess to predict daily cause-specific mortality in summer, using multiple cities across Southern Europe.

METHODS

We fitted time series regression models to summer cause-specific mortality, including natural, respiratory, and cardiovascular causes, in 11 cities across four countries. We included a distributed lag nonlinear model with lags up to 7 days for hot night duration and excess adjusted by daily mean temperature. We summarized city-specific associations as overall-cumulative exposure-response curves at the country level using meta-analysis.

RESULTS

We found positive but generally nonlinear associations between relative risk (RR) of cause-specific mortality and duration and excess of hot nights. RR of duration associated with nonaccidental mortality in Portugal was 1.29 (95% confidence interval [CI] = 1.07, 1.54); other associations were imprecise, but we also found positive city-specific estimates for Rome and Madrid. Risk of hot-night excess ranged from 1.12 (95% CI = 1.05, 1.20) for France to 1.37 (95% CI = 1.26, 1.48) for Portugal. Risk estimates for excess were consistently higher than for duration.

CONCLUSIONS

This study provides new evidence that, over a wider range of locations, hot night indices are strongly associated with cause-specific deaths. Modeling the impact of thermal characteristics during summer nights on mortality could improve decisionmaking for preventive public health strategies.

Publisher Correction to: Temporal dynamics in total excess mortality and COVID-19 deaths in Italian cities

An amendment to this paper has been published and can be accessed via the original article.

Temporal dynamics in total excess mortality and COVID-19 deaths in Italian cities

BACKGROUND

Standardized mortality surveillance data, capable of detecting variations in total mortality at population level and not only among the infected, provide an unbiased insight into the impact of epidemics, like COVID-19 (Coronavirus disease). We analysed the temporal trend in total excess mortality and deaths among positive cases of SARS-CoV-2 by geographical area (north and centre-south), age and sex, taking into account the deficit in mortality in previous months.

METHODS

Data from the Italian rapid mortality surveillance system was used to quantify excess deaths during the epidemic, to estimate the mortality deficit during the previous months and to compare total excess mortality with deaths among positive cases of SARS-CoV-2. Data were stratified by geographical area (north vs centre and south), age and sex.

RESULTS

COVID-19 had a greater impact in northern Italian cities among subjects aged 75-84 and 85+ years. COVID-19 deaths accounted for half of total excess mortality in both areas, with differences by age: almost all excess deaths were from COVID-19 among adults, while among the elderly only one third of the excess was coded as COVID-19. When taking into account the mortality deficit in the pre-pandemic period, different trends were observed by area: all excess mortality during COVID-19 was explained by deficit mortality in the centre and south, while only a 16% overlap was estimated in northern cities, with quotas decreasing by age, from 67% in the 15-64 years old to 1% only among subjects 85+ years old.

CONCLUSIONS

An underestimation of COVID-19 deaths is particularly evident among the elderly. When quantifying the burden in mortality related to COVID-19, it is important to consider seasonal dynamics in mortality. Surveillance data provides an impartial indicator for monitoring the following phases of the epidemic, and may help in the evaluation of mitigation measures adopted.

Mortality impacts of the coronavirus disease (COVID-19) outbreak by sex and age: rapid mortality surveillance system, Italy, 1 February to 18 April 2020

Data from the rapid mortality surveillance system in 19 major Italian cities were used to carry out a timely assessment of the health impact of the COVID-19 epidemic. By 18 April, a + 45% excess in mortality was observed, with a higher impact in the north of the country (+ 76%). The excess was greatest among men, with an increasing trend by age. Surveillance data can be used to evaluate the lockdown and re-opening phases.

The impact of heat waves on mortality in 9 European cities: results from the EuroHEAT project

BACKGROUND

The present study aimed at developing a standardized heat wave definition to estimate and compare the impact on mortality by gender, age and death causes in Europe during summers 1990-2004 and 2003, separately, accounting for heat wave duration and intensity.

METHODS

Heat waves were defined considering both maximum apparent temperature and minimum temperature and classified by intensity, duration and timing during summer. The effect was estimated as percent increase in daily mortality during heat wave days compared to non heat wave days in people over 65 years. City specific and pooled estimates by gender, age and cause of death were calculated.

RESULTS

The effect of heat waves showed great geographical heterogeneity among cities. Considering all years, except 2003, the increase in mortality during heat wave days ranged from + 7.6% in Munich to + 33.6% in Milan. The increase was up to 3-times greater during episodes of long duration and high intensity. Pooled results showed a greater impact in Mediterranean (+ 21.8% for total mortality) than in North Continental (+ 12.4%) cities. The highest effect was observed for respiratory diseases and among women aged 75-84 years. In 2003 the highest impact was observed in cities where heat wave episode was characterized by unusual meteorological conditions.

CONCLUSIONS

Climate change scenarios indicate that extreme events are expected to increase in the future even in regions where heat waves are not frequent. Considering our results prevention programs should specifically target the elderly, women and those suffering from chronic respiratory disorders, thus reducing the impact on mortality.

The impact of heat waves on mortality in 9 European cities: results from the EuroHEAT project

BACKGROUND

The present study aimed at developing a standardized heat wave definition to estimate and compare the impact on mortality by gender, age and death causes in Europe during summers 1990-2004 and 2003, separately, accounting for heat wave duration and intensity.

METHODS

Heat waves were defined considering both maximum apparent temperature and minimum temperature and classified by intensity, duration and timing during summer. The effect was estimated as percent increase in daily mortality during heat wave days compared to non heat wave days in people over 65 years. City specific and pooled estimates by gender, age and cause of death were calculated.

RESULTS

The effect of heat waves showed great geographical heterogeneity among cities. Considering all years, except 2003, the increase in mortality during heat wave days ranged from + 7.6% in Munich to + 33.6% in Milan. The increase was up to 3-times greater during episodes of long duration and high intensity. Pooled results showed a greater impact in Mediterranean (+ 21.8% for total mortality) than in North Continental (+ 12.4%) cities. The highest effect was observed for respiratory diseases and among women aged 75-84 years. In 2003 the highest impact was observed in cities where heat wave episode was characterized by unusual meteorological conditions.

CONCLUSIONS

Climate change scenarios indicate that extreme events are expected to increase in the future even in regions where heat waves are not frequent. Considering our results prevention programs should specifically target the elderly, women and those suffering from chronic respiratory disorders, thus reducing the impact on mortality.

Factors affecting in-hospital heat-related mortality: a multi-city case-crossover analysis

BACKGROUND

Several studies have identified strong effects of high temperatures on mortality at population level; however, individual vulnerability factors associated with heat-related in-hospital mortality are largely unknown. The objective of the study was to evaluate heat-related in-hospital mortality using a multi-city case-crossover analysis.

METHODS

We studied residents of four Italian cities, aged 65+ years, who died during 1997-2004. For 94,944 individuals who died in hospital and were hospitalised two or more days before death, demographics, chronic conditions, primary diagnoses of last event and hospital wards were considered. A city-specific case-crossover analysis was performed to evaluate the association between apparent temperature and mortality. Pooled odds ratios (OR) of dying on a day with a temperature of 30 degrees C compared to a day with a temperature of 20 degrees C were estimated with a random-effects meta-analysis.

RESULTS

We estimated an overall OR of 1.32 (95% confidence interval: 1.25, 1.39). Age, marital status and hospital ward were important risk indicators. Patients in general medicine were at higher risk than those in high and intensive care units. A history of psychiatric disorders and cerebrovascular diseases gave a higher vulnerability. Mortality was greater among patients hospitalised for heart failure, stroke and chronic pulmonary diseases.

CONCLUSIONS

In-hospital mortality is strongly associated with high temperatures. A comfortable temperature in hospitals and increased attention to vulnerable patients during heatwaves, especially in general medicine, are necessary preventive measures.

Temperature and summer mortality: geographical and temporal variations in four Italian cities

STUDY OBJECTIVE

To investigate geographical and temporal variations in the temperature-mortality relation.

DESIGN

The relation between mortality and maximum apparent temperature (Tappmax) in 2003, 2004, and a previous reference period was explored by using segmented regression and generalised additive models.

SETTING

Four Italian cities (Bologna, Milano, Roma, and Torino), included in a national network of prevention programmes and heat health watch warning systems (HHWWS) were considered.

PARTICIPANTS

Daily mortality counts of the resident population dying in each city during summer (June to September).

MAIN RESULTS

The impact of Tappmax on mortality differed between cities and varied in the three periods analysed. The geographical heterogeneity of the J shaped relation was seen in the reference period with Tappmax thresholds ranging from 28 degrees C in Torino to 32 degrees C in Milano and Roma. In all cities, the percentage variation in mortality was greatest in 2003. In Torino and Roma a significant increase was seen also at lower Tappmax values that are usually not associated to an increase in mortality (26-28 degrees C). In summer 2004 the exposure levels were similar to the reference period; only in Torino the effect of Tappmax on mortality remained relevant even if reduced compared with 2003, while in Bologna no statistically significant effect was seen for any temperature range.

CONCLUSIONS

The observed heterogeneous reduction in the impact of temperature on mortality from 2003 to 2004 may be partly explained by the lower levels of exposure. Changes in the ability of individuals and communities to adjust to high temperatures as a consequence of the implementation of public health interventions, based on HHWWS, characterised by a diverse effectiveness, may also have played an important part.