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Background: The impact of heatwaves on public health has led to an urgent need to describe extremely hot weather events (EHWEs) and evaluate their health impacts., Methods: In Hong Kong, a very hot day (VHD) can be defined when the daily maximum temperature ≥ 33 °C, and a hot night (HN) can be identified if the daily minimum temperature ≥ 28 °C. Three lengths of time, nine combinations of VHD and HN, and four categories of occurrence intervals between two EHWEs were considered over 2006-2015. The daily relative risk (RR) of all-cause mortality was estimated using Poisson generalized additive regression models, controlling for both short-term and long-term trends in temperature as well as four air pollutants. Lagged effects of the representative EHWEs were further examined for their association with mortality. Subgroup analysis was conducted for different sex and age groups., Results: Significant associations with raised mortality risks were observed for a single HN, while stronger associations with mortality were observed as significant for five or more consecutive VHDs/HNs. More HNs between the consecutive VHDs also significantly amplified the impact on mortality, with the strongest association observed for EHWEs characterized as 2D3N, and the effect significantly lagged for five days. Therefore, with identifiable health impacts, three thresholds (5VHDs, 5HNs, & 2D3N) were determined to be representative of identical types of EHWEs in Hong Kong. Furthermore, by taking 2 (3) consecutive VHDs (HNs) as one daytime (nighttime) EHWE event, those occurring consecutively without non-hot days (nights) in between were found to be significantly associated with excess mortality risks. Moreover, females and older adults were determined to be relatively more vulnerable to all defined EHWEs., Conclusions: Among all the observed significant heat-mortality associations in highly urbanized cities, EHWEs that occurred during the nighttime, with extended length, consecutively without any break in between, or in the pattern of 2D3N might require the meteorological administration, healthcare providers, and urban planners to work interactively., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Extreme hot weather events are likely to increase under future climate change, and it is exacerbated in urban areas due to the complex urban settings. It causes excess mortality due to prolonged exposure to such extreme heat. However, there is lack of universal definition of prolonged heat or heat wave, which leads to inadequacies of associated risk preparedness. Previous studies focused on estimating temperature-mortality relationship based on temperature thresholds for assessing heat-related health risks but only several studies investigated the association between types of prolonged heat and excess mortality. However, most studies focused on one or a few isolated heat waves, which cannot demonstrate typical scenarios that population has experienced. In addition, there are limited studies on the difference between daytime and nighttime temperature, resulting in insufficiency to conclude the effect of prolonged heat. In sub-tropical high-density cities where prolonged heat is common in summer, it is important to obtain a comprehensive understanding of prolonged heat for a complete assessment of heat-related health risks. In this study, six types of prolonged heat were examined by using a time-stratified analysis. We found that more consecutive hot nights contribute to higher mortality risk while the number of consecutive hot days does not have significant association with excess mortality. For a day after five consecutive hot nights, there were 7.99% [7.64%, 8.35%], 7.74% [6.93%, 8.55%], and 8.14% [7.38%, 8.88%] increases in all-cause, cardiovascular, and respiratory mortality, respectively. Non-consecutive hot days or nights are also found to contribute to short-term mortality risk. For a 7-day-period with at least five non-consecutive hot days and nights, there was 15.61% [14.52%, 16.70%] increase in all-cause mortality at lag 0-1, but only -2.00% [-2.83%, -1.17%] at lag 2-3. Differences in the temperature-mortality relationship caused by hot days and hot nights imply the need to categorize prolonged heat for public health surveillance. Findings also contribute to potential improvement to existing heat-health warning system.

We used data from the 1991-2006 Canadian Census Mortality and Cancer Follow-up Study to compare all-cause mortality for immigrants with that of the Canadian-born population. The study addressed two related questions. First, do immigrants have a mortality advantage over the Canadian-born? Second, if immigrants have a mortality advantage, does it persist as their duration of residence increases? The analysis fitted sex-stratified hazard regression models for the overall sample and for selected countries of birth (UK, China, India, Philippines, and the Caribbean). Predictors were assessed at baseline. Mortality was lower among immigrants than the Canadian-born even after adjusting for a selected group of socio-demographic and socio-economic factors. The mortality differences persisted even after long residence in Canada, but appeared to be dependent on the age of the individual and the country of origin. Interpreted in light of known explanations of immigrant mortality advantage, the results mostly reflect selection effects.

A deeper understanding of extreme hot weather are needed in cities sensitive to heat effects, an investigation was done in the tropical town of Kaohsiung in Taiwan. Its 11 districts were divided into three climatic classes varying from high urban heat, low levels of green space and lack of proximity to water bodies to low urban heat, adequate green space and proximity to water bodies. Daily data on natural mortality, meteorological variables, and pollutants from May-October 1999-2008 were analysed using generalised additive models for the time-series data. Subgroup analyses were conducted, stratifying decedents according to the level of planning activity required in order to mitigate adverse heat effects in their residential areas, classifying districts as "level 1" for those requiring a high level of mitigation action; "level 2" for those requiring some action; and "level 3" for those that need only preserve existing conditions. Stratified analyses showed that mortality increases per 1 °C rise on average, either on the same day or in the previous 4 days (lags 0-4), were associated with 2.8%, 2.3% and -1.3% for level 1, 2 and 3 districts, respectively. The slope describing the association between temperature and mortality was higher above 29.0 °C resulting in corresponding increases of 4.2%, 5.0% and 0.3% per per 1 °C rise in temperature, respectively. Other meteorological variables were not significantly associated with mortality. It is concluded that hot season mortality in Kaohsiung is only sensitive to heat effects in districts classified as having unfavourably climatic conditions and requiring mitigation efforts in city planning. Urban planning measures designed to improve climatic conditions could reduce excess mortality resulting from extreme hot weather.

Background: Prior studies from around the world have indicated that very high temperatures tend to increase summertime mortality. However possible effect modification by urban micro heat islands has only been examined by a few studies in North America and Europe. This study examined whether daily mortality in micro heat island areas of Hong Kong was more sensitive to short term changes in meteorological conditions than in other areas., Method: An urban heat island index (UHII) was calculated for each of Hong Kong's 248 geographical tertiary planning units (TPU). Daily counts of all natural deaths among Hong Kong residents were stratified according to whether the place of residence of the decedent was in a TPU with high (above the median) or low UHII. Poisson Generalized Additive Models (GAMs) were used to estimate the association between meteorological variables and mortality while adjusting for trend, seasonality, pollutants and flu epidemics. Analyses were restricted to the hot season (June-September)., Results: Mean temperatures (lags 0-4) above 29 °C and low mean wind speeds (lags 0-4) were significantly associated with higher daily mortality and these associations were stronger in areas with high UHII. A 1 °C rise above 29 °C was associated with a 4.1% (95% confidence interval (CI): 0.7%, 7.6%) increase in natural mortality in areas with high UHII but only a 0.7% (95% CI: -2.4%, 3.9%) increase in low UHII areas. Lower mean wind speeds (5(th) percentile vs. 95(th) percentile) were associated with a 5.7% (95% CI: 2.7, 8.9) mortality increase in high UHII areas vs. a -0.3% (95% CI: -3.2%, 2.6%) change in low UHII areas., Conclusion: The results suggest that urban micro heat islands exacerbate the negative health consequences of high temperatures and low wind speeds. Urban planning measures designed to mitigate heat island effects may lessen the health effects of unfavorable summertime meteorological conditions.

According to the 2006 Census, almost the Canadian population were foreign-born, a percentage that is projected to reach at least 25% by 2031. Studies based on age-standardized mortality rates (ASMR) have found a healthy immigrant effect, with lower overall rates among immigrants. A duration effect has also been observed-immigrants' mortality advantage lessened as their time in Canada increased. ASMRs based on the 1991 to 2001 census mortality follow-up study indicate a healthy immigrant effect and a duration effect at the national level for all-cause mortality for both sexes. However, at the national level, the mortality rate among women from the United States and from Sub-Saharan Africa was similar to that of Canadian-born women. For the three largest Census Metropolitan Areas (Toronto, Montreal and Vancouver), a healthy immigrant effect was not observed among women or among most men from the United States or Sub-Saharan Africa.

Objectives: This article describes changes in income-related differences in mortality in Canada from 1971 to 1996, including trends by specific causes of death. Data source: Death registration and population data for residents of census metropolitan areas (CMAs) were obtained from the Canadian Mortality Data Base and population censuses for 1971, 1986, 1991, and 1996. The death data were then coded to census tract (CT), and institutional residents were identified (for exclusion). Analytical techniques: Within each CMA, the non-institutional population and deaths were grouped into neighbourhood income quintiles on the basis of the CT percentage of population below Canada's low-income cut-offs. Life expectancy at birth, probability of survival to age 75, potential years of life lost (PYLL), and income-related excess PYLL before age 75 were calculated, as were age-specific mortality rates and age- standardized mortality rates (ASMRs) for major causes of death. Main results: From 1971 to 1996, differences in life expectancy between the richest and poorest income quintiles of urban Canada diminished by well over 1 year for each sex (from 6.3 to 5.0 years for males, and from 2.8 to 1.6 years for females). Inter-quintile differences in infant mortality declined by 7 per thousand (76%). The rate of income-related excess potential years of life lost (PYLL) before age 75 diminished by 35%. By 1996 the major causes of death contributing to excess PYLL were circulatory diseases, injuries, neoplasms, and infectious diseases. For most causes of death (notably ischemic heart disease, most injuries, cirrhosis of the liver, and perinatal conditions), socio-economic disparities in mortality diminished markedly over time. However, some causes of death (such as lung cancer, prostate cancer and suicide for males, and breast cancer for females) showed little change, while a few (lung cancer for females, and infectious diseases, mental disorders and diabetes for both sexes) showed cl... INSETS: Methods;Restrictions and coding to CT and quintile;Other studies on socio-economic differentials in circulatory . .;Differential vulnerability to lung cancer among smokers, and . . [ABSTRACT FROM AUTHOR]

• There is lack of evidence regarding attributable burden on cause-specific mortality in Hong Kong. • Non-optimal ambient temperatures accounted for almost 5% of total mortality. • Exposure to extreme temperatures are associated with a greater risk of mortality, but moderate temperature resulted in the greatest burden of deaths. • Cold temperatures generally contributed to higher attributable risks of mortality than hot temperatures. • Findings are important for local decision making to reduce public health burden due to the varies MMTs and AF of temperature by groups. This study aimed to quantify the mortality burden attributable to non-optimal cold and hot conditions from moderate and extreme temperatures in Hong Kong during 2006-2016. The association between mortality and daily mean temperature was assessed using a distributed lag non-linear model (DLNM) integrated with a quasi-Poisson model. The cumulated effects of cold and hot temperature were firstly quantified. The attributable risks of non-optimal ambient temperature on deaths by cause-specific mortality and age groups were then estimated. A reversed J-shaped relationship was found between temperature and total mortality. The highest increase in risk was at extreme cold, with the highest relative risk (RR) for injuries of 2.18 (95%CI: 1.03-4.62), followed by the respiratory and circulatory system diseases for lag 0-21 days. Cold temperature was associated with a greater burden of death than hot temperature, with attributable fractions (AF) of 4.72% and 0.16%, respectively. Moderate temperatures played a major role in all-cause mortality with AF of 4.25%, and 0.63% for extreme temperature. Most of the temperature-related mortality burden was attributed to moderate weather, suggesting relevant temperature-related preventive strategies and measurements should be implemented to minimize the negative impact of temperatures on population health, particularly for vulnerable sub-populations. [ABSTRACT FROM AUTHOR]