Chun-Quan Ou

The effects of air pollution on mortality in socially deprived urban areas in Hong Kong, China

Background Poverty is a major determinant of population health, but little is known about its role in modifying air pollution effects. Objectives We set out to examine whether people residing in socially deprived communities are at higher mortality risk from ambient air pollution. Methods This study included 209 tertiary planning units (TPUs), the smallest units for town planning in the Special Administrative Region of Hong Kong, China. The socioeconomic status of each TPU was measured by a social deprivation index (SDI) derived from the proportions of the population with a) unemployment, b) monthly household income < US

Epidemiology of chronic rhinosinusitis: results from a cross-sectional survey in seven Chinese cities

250, c) no schooling at all, d) one-person household, e) never-married status, and f ) subtenancy, from the 2001 Population Census. TPUs were classified into three levels of SDI: low, middle, and high. We performed time-series analysis with Poisson regression to examine the association between changes in daily concentrations of ambient air pollution and daily number of deaths in each SDI group for the period from January 1996 to December 2002. We evaluated the differences in pollution effects between different SDI groups using a case-only approach with logistic regression. Results We found significant associations of nitrogen dioxide, sulfur dioxide, particulate matter with aerodynamic diameter < 10 μm, and ozone with all nonaccidental and cardiovascular mortality in areas of middle or high SDI (p < 0.05). Health outcomes, measured as all nonaccidental, cardiovascular, and respiratory mortality, in people residing in high SDI areas were more strongly associated with SO2 and NO2 compared with those in middle or low SDI areas. Conclusions Neighborhood socioeconomic deprivation increases mortality risks associated with air pollution.

Daily visibility and mortality: Assessment of health benefits from improved visibility in Hong Kong

Chronic sinusitis (CRS) is a common otorhinolaryngologic disease that is frequently encountered in everyday practice, but there is a lack of precise data regarding the prevalence of CRS in developing countries. We performed a national investigation in China to determine the prevalence and associated factors of CRS.

Excess Winter Mortality and Cold Temperatures in a Subtropical City, Guangzhou, China

n Abstractn n Visibility in Hong Kong has deteriorated significantly over 40 years with visibility below 8km in the absence of fog, mist, or precipitation, increasing from 6.6 days in 1968 to 54.1 days in 2007. We assessed the short-term mortality effects of daily loss of visibility. During 1996–2006, we obtained mortality data for non-accidental and cardiorespiratory causes, visibility recorded as visual range in kilometers, temperature, and relative humidity from an urban observatory, and concentrations of four criteria pollutants. A generalized additive Poisson regression model with penalized cubic regression splines was fitted to control for time variant covariates. For non-accidental mortality, an interquartile range (IQR) of 6.5km decrease in visibility at lag0–1 days was associated with an excess risk (ER%) [95% CI] of 1.13 [0.49, 1.76] for all ages and 1.37 [0.65, 2.09] for ages 65 years and over; for cardiovascular mortality of 1.31 [0.13, 2.49] for all ages, and 1.72 [0.44, 3.00] for ages 65 years and over; and for respiratory mortality of 1.92 [0.49, 3.35] for all ages and 1.76 [0.28, 3.25] for ages 65 years and over. The estimated ER% for daily mortality derived from both visibility and air pollutant data were comparable in terms of magnitude, lag pattern, and exposure–response relationships especially when using particulate matter with aerodynamic diameter ≤10μm to predict the mortality associated with visibility. Visibility provides a useful proxy for the assessment of environmental health risks from ambient air pollutants and a valid approach for the assessment of the public health impacts of air pollution and the benefits of air quality improvement measures in developing countries where pollutant monitoring data are scarce.n n

Estimating years of life lost from cardiovascular mortality related to air pollution in Guangzhou, China

Background A significant increase in mortality was observed during cold winters in many temperate regions. However, there is a lack of evidence from tropical and subtropical regions, and the influence of ambient temperatures on seasonal variation of mortality was not well documented. Methods This study included 213,737 registered deaths from January 2003 to December 2011 in Guangzhou, a subtropical city in Southern China. Excess winter mortality was calculated by the excess percentage of monthly mortality in winters over that of non-winter months. A generalized linear model with a quasi-Poisson distribution was applied to analyze the association between monthly mean temperature and mortality, after controlling for other meteorological measures and air pollution. Results The mortality rate in the winter was 26% higher than the average rate in other seasons. On average, there were 1,848 excess winter deaths annually, with around half (52%) from cardiovascular diseases and a quarter (24%) from respiratory diseases. Excess winter mortality was higher in the elderly, females and those with low education level than the young, males and those with high education level, respectively. A much larger winter increase was observed in out-of-hospital mortality compared to in-hospital mortality (45% vs. 17%). We found a significant negative correlation of annual excess winter mortality with average winter temperature (rs=-0.738, P=0.037), but not with air pollution levels. A 1 °C decrease in monthly mean temperature was associated with an increase of 1.38% (95%CI:0.34%-2.40%) and 0.88% (95%CI:0.11%-1.64%) in monthly mortality at lags of 0-1 month, respectively. Conclusion Similar to temperate regions, a subtropical city Guangzhou showed a clear seasonal pattern in mortality, with a sharper spike in winter. Our results highlight the role of cold temperature on the winter mortality even in warm climate. Precautionary measures should be strengthened to mitigate cold-related mortality for people living in warm climate.

The impact of ambient air pollution on suicide mortality: a case-crossover study in Guangzhou, China.

Previous studies have mainly used mortality or morbidity as the health outcome to examine the air pollution-health association. Little evidence is available on relationships between air pollutants and years of life lost (YLL). We aimed to estimate the YLL from cardiovascular mortality due to air pollution. Daily data on weather and air pollutants and individual data of all registered deaths for years 2004-2007 were obtained in Guangzhou, China. The generalized additive model was used to assess the YLL associated with 10μg/m3 increases in NO2, SO2 and PM10. We found that the mean daily YLL was 248, 87.5 and 73.7 for deaths from cardiovascular disease (CVD), stroke and ischemic heart disease (IHD), respectively. A significant linear correlation was observed between air pollution and YLL due to cardiovascular disease. The effects of air pollutants on YLL were immediate and lasted for two days. A 10μg/m3 increase above the corresponding threshold of 55.6μg/m3, 40.4μg/m3 and 0μg/m3 in NO2, PM10 and SO2 was related to YLL increase of 1.8 (95% CI: 0.8-2.9), 2.8 (1.7-3.8) and 2.6 (1.2-4.0) years at lag 0-1days for CVD, respectively. The estimates of YLL associated with NO2 and PM10 were higher in men than women. The air pollutants-related YLL was higher among young people and those with low education level, compared to the elderly and those with high education level, respectively. These findings confirmed YLL provides a complementary strategy for assessing the health effect of air pollution. This study underscores the necessity of the reduction of air pollution benefiting public health.

Influence of Self-Reported Chronic Rhinosinusitis on Health-Related Quality of Life: A Population-Based Survey

BackgroundPreventing suicide is a global imperative. Although the effects of social and individual risk factors of suicide have been widely investigated, evidence of environmental effects of exposure to air pollution is scarce. We investigated the effects of ambient air pollution on suicide mortality in Guangzhou, China during 2003−2012.MethodsA conditional logistic regression analysis with a time-stratified case-crossover design was performed to assess the effects of daily exposure to three standard air pollutants, including particulate matter less than 10xa0μm in aerodynamic diameter (PM10), sulphur dioxide (SO2) and nitrogen dioxide (NO2), on suicide mortality, after adjusting for the confounding effects of daily mean temperature, relative humidity, atmospheric pressure and sunshine duration. Further analyses were stratified by season, gender, age group, educational attainment and suicide type.ResultsBetween 2003 and 2012, there were a total of 1 550 registered suicide deaths in Guangzhou. A significant increase in suicide risk were associated with interquartile-range increases in the concentration of air pollutant, with an odds ratio of 1.13 (95xa0% confidence interval (CI): 1.01, 1.27) and 1.15 (95xa0% CI: 1.03, 1.28) for PM10 and NO2 at lag 02, and 1.12 (95xa0% CI: 1.02, 1.23) for SO2 at lag 01, respectively. The suicide risks related to air pollution for males and people with high education level were higher than for females and those with low education level, respectively. Significant air pollution effects were found on violent suicide mortality and in cool season but not on non-violent suicide mortality or in warm season.ConclusionsSuicide risk was positively associated with ambient air pollution levels. This finding would provide important information for the health impact assessment of air pollution and for the development of effective strategies and interventions for the prevention of suicide.

Short-term effects of particulate air pollution on male smokers and never-smokers.

Chronic rhinosinusitis (CRS) is a frequently occurring chronic respiratory disease. There is evidence that effective treatment of CRS can improve patients’ quality of life, but the data regarding the extent to which CRS impairs patients’ quality of life (QoL) is sparse. This study aimed to evaluate the effect of self-reported CRS on health-related QoL and to determine whether the influence was associated with gender, age and socio-economic status. A four-stage random sampling method was used to select the participants from the general population in Guangzhou, China. All participants were interviewed face-to-face at their homes using a standardized questionnaire. The health-related QoL of each participant was assessed using the SF-36 Health Survey. The scores of the SF-36 after adjusting for gender, age, socioeconomic conditions, smoking and some important comorbid conditions were compared between the CRS group and the non-CRS group using analysis of covariance. A multiple linear regression model with interaction terms was established to determine whether CRS affected QoL to the same degree across the different subpopulations. Among a total of 1,411 participants aged at least 15 years, 118 persons (8.4%) had self-reported CRS. Subjects with CRS had an increased prevalence of allergic rhinitis, chronic obstructive pulmonary disease and gout than subjects without CRS. The CRS group had lower scores in all eight domains and the physical and mental component summary than those without CRS (P<0.05), and the greatest differences were in role emotional function (RE), general health (GH) and role physical function (RP). The impairments of the CRS participants in RE and RP were greater among the females than the males. Moreover, physical domains were affected to greater degrees among the elderly and those with high-level education. In conclusion, CRS is a common chronic disorder. Persons with self-reported CRS perceived themselves as having impaired QoL in both the physical and mental domains. These findings shed new light on the health burden of CRS and should be taken into account by clinicians involved in the care of CRS patients.

Dietary habits and the short-term effects of air pollution on mortality in the Chinese population in Hong Kong

Background: Numerous studies have shown that ambient air pollution and smoking are both associated with increased mortality, but until now there has been little evidence as to whether the effects of these 2 factors combined are greater than the sum of their individual effects. We assessed whether smokers are subject to additional mortality risk from air pollution relative to never-smokers. Methods: This study included 10,833 Chinese men in Hong Kong who died at the age of 30 or above during the period 1 January to 31 December 1998. Relatives who registered for deceased persons were interviewed about the deceaseds smoking history and other personal lifestyle factors about 10 years before death. Poisson regression for daily number of deaths was fitted to estimate excess risks per 10 &mgr;g/m3 increase in particulate matter with aerodynamic diameter <10 &mgr;m (PM10) in male smokers and never-smokers in stratified data, and additional excess risk for smokers relative to never-smokers in combined data. Results: In smokers there was a significant excess risk associated with PM10 for all natural causes and cardio-respiratory diseases for men age 30 years or older and men 65 or older. For all natural causes, greater excess risk associated with PM10 was observed for smokers relative to never-smokers: 1.9% (95% confidence interval = 0.3% to 3.6%) in men age 30 and older and 2.3% (0.4% to 4.3%) in those age 65 and older. Conclusions: Ambient particulate air pollution is associated with greater excess mortality in male smokers compared with never-smokers.

Mortality as a function of dust-haze in China: a multi-city time-series study

Background Both diet and air pollution are associated with mortality risks. However, no epidemiological study has examined the potential interaction between diet and air pollution on mortality. We assessed their interaction on an additive scale. Methods We analysed the data on daily concentrations of ambient air pollutants (PM10, NO2, SO2 and O3) and a total of 23u2008484 deaths in 1998 in Hong Kong. A standardised questionnaire was used in all four death registries to collect food frequency data from proxy respondents while waiting for the registration to be completed. We fitted a linear odds ratio model and estimated excess relative risk due to the interaction (ERRI) between air pollution and regular consumption (at least once per week) of each food item to measure departure from additivity of effects on mortality. Results We observed consistently negative ERRI between all of the four pollutants and regular consumption of vegetables, fruits and soy. The effects of PM10, NO2 and O3 were significant smaller in the subjects who regularly consumed fruits than those who never or seldom consumed such food. The effect modification of soy consumption on PM10, NO2 and SO2 associated mortality was also found statistically significant. However, regular consumption of dairy products was associated with significant increased effects of PM10 and NO2. Conclusions This study provides insight into dietary habit as one of the modifiers of health effects of air pollution. Our findings merit further studies to characterise the influence of diet on air pollution-related health and elucidate the underlying mechanisms.