Although studies have provided estimates of premature deaths attributable to either heat or cold in selected countries, none has so far offered a systematic assessment across the whole temperature range in populations exposed to different climates. We aimed to quantify the total mortality burden attributable to non-optimum ambient temperature, and the relative contributions from heat and cold and from moderate and extreme temperatures. We collected data for 384 locations in Australia, Brazil, Canada, China, Italy, Japan, South Korea, Spain, Sweden, Taiwan, Thailand, UK, and USA. We fitted a standard time-series Poisson model for each location, controlling for trends and day of the week. We estimated temperature-mortality associations with a distributed lag non-linear model with 21 days of lag, and then pooled them in a multivariate metaregression that included country indicators and temperature average and range. We calculated attributable deaths for heat and cold, defined as temperatures above and below the optimum temperature, which corresponded to the point of minimum mortality, and for moderate and extreme temperatures, defined using cutoffs at the 2·5th and 97·5th temperature percentiles. We analysed 74,225,200 deaths in various periods between 1985 and 2012. In total, 7·71% (95% empirical CI 7·43-7·91) of mortality was attributable to non-optimum temperature in the selected countries within the study period, with substantial differences between countries, ranging from 3·37% (3·06 to 3·63) in Thailand to 11·00% (9·29 to 12·47) in China. The temperature percentile of minimum mortality varied from roughly the 60th percentile in tropical areas to about the 80-90th percentile in temperate regions. More temperature-attributable deaths were caused by cold (7·29%, 7·02-7·49) than by heat (0·42%, 0·39-0·44). Extreme cold and hot temperatures were responsible for 0·86% (0·84-0·87) of total mortality. Most of the temperature-related mortality burden was attributable to the contribution of cold. The effect of days of extreme temperature was substantially less than that attributable to milder but non-optimum weather. This evidence has important implications for the planning of public-health interventions to minimise the health consequences of adverse temperatures, and for predictions of future effect in climate-change scenarios. UK Medical Research Council.

Rationale: Episode analyses of heat waves have documented a comparatively higher impact on mortality than on morbidity (hospital admissions) in European cities. The evidence from daily time series studies is scarce and inconsistent. Objectives: To evaluate the impact of high environmental temperatures on hospital admissions during April to September in 12 European cities participating in the Assessment and Prevention of Acute Health Effects of Weather Conditions in Europe (PHEWE) project. Methods: For each city, time series analysis was used to model the relationship between maximum apparent temperature (lag 0–3 days) and daily hospital admissions for cardiovascular, cerebrovascular, and respiratory causes by age (all ages, 65–74 age group, and 75+ age group), and the city-specific estimates were pooled for two geographical groupings of cities. Measurements and Main Results: For respiratory admissions, there was a positive association that was heterogeneous between cities. For a 1°C increase in maximum apparent temperature above a threshold, respiratory admissions increased by +4.5% (95% confidence interval, 1.9–7.3) and +3.1% (95% confidence interval, 0.8–5.5) in the 75+ age group in Mediterranean and North-Continental cities, respectively. In contrast, the association between temperature and cardiovascular and cerebrovascular admissions tended to be negative and did not reach statistical significance. Conclusions: High temperatures have a specific impact on respiratory admissions, particularly in the elderly population, but the underlying mechanisms are poorly understood. Why high temperature increases cardiovascular mortality but not cardiovascular admissions is also unclear. The impact of extreme heat events on respiratory admissions is expected to increase in European cities as a result of global warming and progressive population aging.

A peer-reviewed open access journal published by the National Institute of Environmental Health Sciences

Due to climate change and other factors, air pollution patterns are changing in several urbanised areas of the world, with a significant effect on respiratory health both independently and synergistically with weather conditions; climate scenarios show Europe as one of the most vulnerable regions. European studies on heatwave episodes have consistently shown a synergistic effect of air pollution and high temperatures, while the potential weather–air pollution interaction during wildfires and dust storms is unknown. Allergen patterns are also changing in response to climate change, and air pollution can modify the allergenic potential of pollens, especially in the presence of specific weather conditions. The underlying mechanisms of all these interactions are not well known; the health consequences vary from decreases in lung function to allergic diseases, new onset of diseases, exacerbation of chronic respiratory diseases, and premature death. These multidimensional climate–pollution–allergen effects need to be taken into account in estimating both climate and air pollution-related respiratory effects, in order to set up adequate policy and public health actions to face both the current and future climate and pollution challenges.

Objectives:Adverse effects have been reported of prenatal and/or postnatal passive exposure to smoking on children’s health. Uncertainties remain about the relative importance of smoking at different periods in the child’s life. We investigate this in a pooled analysis, on 53 879 children from 12 cross-sectional studies—components of the PATY study (Pollution And The Young).Methods:Effects were estimated, within each study, of three exposures: mother smoked during pregnancy, parental smoking in the first two years, current parental smoking. Outcomes were: wheeze, asthma, “woken by wheeze”, bronchitis, nocturnal cough, morning cough, “sensitivity to inhaled allergens” and hay fever. Logistic regressions were used, controlling for individual risk factors and study area. Heterogeneity between study-specific results, and mean effects (allowing for heterogeneity) were estimated using meta-analytical tools.Results:There was strong evidence linking parental smoking to wheeze, asthma, bronchitis and nocturnal cough, with mean odds ratios all around 1.15, with independent effects of prenatal and postnatal exposures for most associations.Conclusions:Adverse effects of both pre- and postnatal parental smoking on children’s respiratory health were confirmed. Asthma was most strongly associated with maternal smoking during pregnancy, but postnatal exposure showed independent associations with a range of other respiratory symptoms. All tobacco smoke exposure has serious consequences for children’s respiratory health and needs to be reduced urgently.