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postgraduate thesis: The role of temperature on morbidity and mortality in Hong Kong
Title | The role of temperature on morbidity and mortality in Hong Kong |
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Authors | |
Issue Date | 2017 |
Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
Citation | Sun, S. [孫生志]. (2017). The role of temperature on morbidity and mortality in Hong Kong. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. |
Abstract | A vast body of epidemiological studies consistently reported that exposure to extreme low
and high temperature was both associated with increased risks of morbidity and mortality.
However, risk estimates of temperature showed substantial heterogeneity according to
geographical regions. The effect heterogeneity may be due to differences in the
characteristics of population. However, little is known about the effect heterogeneity of
temperature by health conditions. Therefore, a distributed lag non-linear model was
incorporated into a nested case-control study design to assess the nonlinear and delayed
mortality effects of temperature in the elders with diabetes mellitus, circulatory system
diseases, chronic obstructive pulmonary disease, and elders absent of these three diseases,
respectively. The cumulative relative risks of temperature were greater in elders with health problems, which suggested that elders with pre-existing diseases were more vulnerable to
temperature.
Climate change not only increases the global mean temperature but also leads to unstable
weather events, including changing temperature variability. Despite extensive investigations
on health impacts of mean temperature, evidence on the health effects of temperature
variability is sparse, especially for long-term temperature variability (e.g. seasonal).
Therefore, a time-varying Cox proportional hazards regression was applied to estimate the
hazard ratios of seasonal temperature variability (defined as the standard deviation of
summertime and wintertime temperature) for the incidence of total respiratory, pneumonia,
and chronic obstructive pulmonary disease, respectively. Wintertime temperature variability
was associated with increased risks of incident respiratory diseases.
Air pollution is the world’s largest single environmental health risk according to World
Health Organization, which caused around 7 million deaths in 2012. Daily temperature and
climate may both modify the adverse health effects of air pollution. However, few studies
have been conducted to investigate such modification effects. I conducted a time-series study
to assess the effect modification of daily temperature on the mortality effects of air pollution
by fitting a temperature-stratified generalized additive model. Temperature was classified into
low, medium, and high temperature strata, and excess risks of air pollution on mortality were
estimated in these three temperature strata, respectively. Excess risks of air pollution were
found to be stronger in low temperature strata than in high strata for all-natural mortality. To explore the effect modification of urban climate, urban climatic class derived from the Hong
Kong Urban Climatic Analysis Map was used to classify participants from the Hong Kong
Chinese Elderly cohort into different climate types according to their residential addresses,
and a time-stratified case-crossover study was then conducted to estimate the adverse health
effects of air pollution in those corresponding climate types. Urban climate was found to
increase the mortality risks of pneumonia associated with air pollution.
In summary, pre-existing health problems increase elders’ susceptibility to extreme
temperature. Seasonal temperature variability is hazardous to human health. Daily
temperature and climate may both intensify the adverse health effects of air pollution.
|
Degree | Doctor of Philosophy |
Subject | Mortality - China - Hong Kong Temperature - Physiological effect |
Dept/Program | Public Health |
Persistent Identifier | http://hdl.handle.net/10722/270232 |
DC Field | Value | Language |
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dc.contributor.author | Sun, Shengzhi | - |
dc.contributor.author | 孫生志 | - |
dc.date.accessioned | 2019-05-23T02:26:16Z | - |
dc.date.available | 2019-05-23T02:26:16Z | - |
dc.date.issued | 2017 | - |
dc.identifier.citation | Sun, S. [孫生志]. (2017). The role of temperature on morbidity and mortality in Hong Kong. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. | - |
dc.identifier.uri | http://hdl.handle.net/10722/270232 | - |
dc.description.abstract | A vast body of epidemiological studies consistently reported that exposure to extreme low and high temperature was both associated with increased risks of morbidity and mortality. However, risk estimates of temperature showed substantial heterogeneity according to geographical regions. The effect heterogeneity may be due to differences in the characteristics of population. However, little is known about the effect heterogeneity of temperature by health conditions. Therefore, a distributed lag non-linear model was incorporated into a nested case-control study design to assess the nonlinear and delayed mortality effects of temperature in the elders with diabetes mellitus, circulatory system diseases, chronic obstructive pulmonary disease, and elders absent of these three diseases, respectively. The cumulative relative risks of temperature were greater in elders with health problems, which suggested that elders with pre-existing diseases were more vulnerable to temperature. Climate change not only increases the global mean temperature but also leads to unstable weather events, including changing temperature variability. Despite extensive investigations on health impacts of mean temperature, evidence on the health effects of temperature variability is sparse, especially for long-term temperature variability (e.g. seasonal). Therefore, a time-varying Cox proportional hazards regression was applied to estimate the hazard ratios of seasonal temperature variability (defined as the standard deviation of summertime and wintertime temperature) for the incidence of total respiratory, pneumonia, and chronic obstructive pulmonary disease, respectively. Wintertime temperature variability was associated with increased risks of incident respiratory diseases. Air pollution is the world’s largest single environmental health risk according to World Health Organization, which caused around 7 million deaths in 2012. Daily temperature and climate may both modify the adverse health effects of air pollution. However, few studies have been conducted to investigate such modification effects. I conducted a time-series study to assess the effect modification of daily temperature on the mortality effects of air pollution by fitting a temperature-stratified generalized additive model. Temperature was classified into low, medium, and high temperature strata, and excess risks of air pollution on mortality were estimated in these three temperature strata, respectively. Excess risks of air pollution were found to be stronger in low temperature strata than in high strata for all-natural mortality. To explore the effect modification of urban climate, urban climatic class derived from the Hong Kong Urban Climatic Analysis Map was used to classify participants from the Hong Kong Chinese Elderly cohort into different climate types according to their residential addresses, and a time-stratified case-crossover study was then conducted to estimate the adverse health effects of air pollution in those corresponding climate types. Urban climate was found to increase the mortality risks of pneumonia associated with air pollution. In summary, pre-existing health problems increase elders’ susceptibility to extreme temperature. Seasonal temperature variability is hazardous to human health. Daily temperature and climate may both intensify the adverse health effects of air pollution. | - |
dc.language | eng | - |
dc.publisher | The University of Hong Kong (Pokfulam, Hong Kong) | - |
dc.relation.ispartof | HKU Theses Online (HKUTO) | - |
dc.rights | The author retains all proprietary rights, (such as patent rights) and the right to use in future works. | - |
dc.rights | This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. | - |
dc.subject.lcsh | Mortality - China - Hong Kong | - |
dc.subject.lcsh | Temperature - Physiological effect | - |
dc.title | The role of temperature on morbidity and mortality in Hong Kong | - |
dc.type | PG_Thesis | - |
dc.description.thesisname | Doctor of Philosophy | - |
dc.description.thesislevel | Doctoral | - |
dc.description.thesisdiscipline | Public Health | - |
dc.description.nature | published_or_final_version | - |
dc.identifier.doi | 10.5353/th_991044104201503414 | - |
dc.date.hkucongregation | 2017 | - |
dc.identifier.mmsid | 991044104201503414 | - |