A novel framework for decomposing PM2.5 variation and demographic change effects on human exposure using satellite observations.

Human exposure to PM2.5, represented by population-weighted mean PM2.5 concentration (cρ), declines under three conditions: (1) mean PM2.5 concentration declines, (2) PM2.5 concentration within urban areas goes through more of a decrease than within rural areas, or (3) city planning relocates people into cleaner areas. Decomposing these effects on human exposure is essential to guide future environmental policies. The lack of ground PM2.5 observations limits the assessment of human exposure to PM2.5 over China. This study proposed a novel diagnostic framework using satellite observations to decompose the variation in cρ resulting from change in the mean PM2.5 concentration, spatial difference in PM2.5 change, and demographic change. In this framework, we decomposed cρ into mean PM2.5 concentration (c0) and pollution-population-coincidence induced PM2.5 exposure (PPCE). We then used this framework to decompose the variation in cρ over China within three recent Five-Year Plans (FYPs) (2001-2015). The results showed that the decline in c0 reduced cρ in most provinces within the eleventh and twelfth FYPs. The spatial difference in PM2.5 change reduced the PPCE and cρ in most provinces within the tenth and twelfth FYPs, with the most substantial reduction rate of -3.64 µg m-3·yr-1 in Tianjin within the twelfth FYP. Rural-to-urban migration resulting from rapid urbanization, however, increased the PPCE and cρ (by as much as 0.22 µg m-3·yr-1) in all provinces except Taiwan within all three FYPs. The demographic change reduced cρ in Taiwan because of the migration of population into less polluted areas. To better reduce human exposure, it is recommended that control efforts further target populous residential areas and urbanization planning relocates people into less polluted areas. Our decomposition framework paves a new way to decompose the human exposure to other air pollutants in China and other regions.

Association between air pollution and general outpatient clinic consultations for upper respiratory tract infections in Hong Kong.

BACKGROUND AND OBJECTIVES: Many studies have shown the adverse effects of air pollution on respiratory health, but few have examined the effects of air pollution on service utilisation in the primary care setting. The aim of this study was to examine the association between air pollution and the daily number of consultations due to upper respiratory tract infections (URTIs) in general outpatient clinics (GOPCs) in Hong Kong. METHODS: Daily data on the numbers of consultations due to URTIs in GOPCs, the concentrations of major air pollutants, and the mean values of metrological variables were retrospectively collected over a 3-year period (2008-2010, inclusive). Generalised additive models were constructed to examine the association between air pollution and the daily number of consultations, and to derive the relative risks and 95% confidence intervals (95% CI) of GOPC consultations for a unit increase in the concentrations of air pollutants. RESULTS: The mean daily consultations due to URTIs in GOPCs ranged from 68.4 to 253.0 over the study period. The summary relative risks (and 95% CI) of daily consultations in all GOPCs for the air pollutants PM10, NO2, O3, and SO2 were 1.005 (1.002, 1.009), 1.010 (1.006, 1.013), 1.009 (1.006, 1.012), and 1.004 (1.000, 1.008) respectively, per 10 µg/m(3) increase in the concentration of each pollutant. CONCLUSION: Significant associations were found between the daily number of consultations due to URTIs in GOPCs and the concentrations of air pollutants, implying that air pollution incurs a substantial morbidity and increases the burden of primary health care services.

Levels of PCDDs, PCDFs, and dioxin-like PCBs in human milk among Hong Kong mothers.

Dioxins are a family of persistent organic pollutants (POPs) listed under the Stockholm Convention, and include PCDDs, PCDFs, and dioxin-like PCBs. These toxic chemicals are carcinogenic, widely dispersed, and have long half-lives. They have contaminated the food web and, being fat-soluble, accumulate in adipose tissues and milk in the human body. To assess human exposure, we collected breast milk samples from 137 first-time mothers recruited from around Hong Kong. Samples were analysed by HRGC-HRMS in four pools, according to the subject's age and length of residency. Exposure was related to age, duration of stay, and possibly diet. Generally, older mothers, and mothers with a longer stay in Hong Kong, had higher levels of dioxins in their milk. This pattern was clearest for the PCBs, although deviations were observed for some of the PCDD/Fs. Mean concentrations, measured per gram of lipid weight in terms of WHO toxic equivalents (WHO-TEQs), were 7.48 pg/g for PCDD/Fs and 3.79 pg/g for PCBs, giving a total of 11.27 pg/g for PCDD/Fs and PCBs combined. Compared to an earlier Hong Kong study we conducted in 2002, the mean WHO-TEQ values in our latest findings were about 9% lower overall for PCDD/Fs and 19% lower for PCBs, with the mean total WHO-TEQ for PCDD/Fs and PCBs being around 13% lower in this study. This indicates a general declining trend in the levels of POPs in Hong Kong. However, our levels were still high when compared to those in some other Asian-Pacific countries. More stringent policies on reducing and eliminating POPs should help to lower these. Continued surveillance for POPs in human milk, as well as in common foodstuffs, will provide us with important information on human exposures that will be necessary for tracking our progress, and making future health risk assessments.

Effect of dust storm events on daily emergency admissions for cardiovascular diseases.

BACKGROUND: Dust storm is a meteorological phenomenon and dust particles have been suspected as harmful to heart and lungs. The aim of this study was to investigate the association between coarse particles and emergency hospital admissions for cardiovascular diseases (CVD) in Hong Kong. METHODS AND RESULTS: Data on mean daily emergency admissions for CVD to major hospitals in Hong Kong, concentrations of air pollutants and meteorological variables from January 1998 to December 2002 were obtained from several government departments. We identified 5 dust storm days during the study period. Independent t-tests were used to compare the mean daily number of admissions on dust storm and non-dust storm days. Case-crossover analysis, using the Poisson regression, was used to examine the effects of coarse particles' concentration on emergency hospital admissions for CVD. A marginally significant increase in emergency hospital admissions for ischemic heart disease (IHD) was found with RR=1.04 (95% confidence interval: 1.00, 1.08) per 10 µg/m(3) increase in the concentration of coarse particles. CONCLUSIONS: This study demonstrated a marginally significant increase in emergency hospital admissions for IHD on the day of dust storm events in Hong Kong, when the levels of coarse particles were very high. Further studies are required to assess the role of coarse particles on cardiac health.

Effect of dust storm events on daily emergency admissions for respiratory diseases.

BACKGROUND AND OBJECTIVE: The harmful effect of dust storm on lung health is controversial. This study aimed to assess any associations between dust storms and emergency hospital admissions due to respiratory disease in Hong Kong. METHODS: Data on daily emergency admissions for respiratory diseases to major hospitals in Hong Kong, and indices of air pollutants and meteorological variables from January 1998 to December 2002 were obtained from several government departments. We identified five dust storm days during the study period. Independent t-tests were used to compare the mean daily number of admissions on dust storm and non-dust storm days. Case-crossover analysis using the Poisson regression was used to examine the effects of PM(10) to emergency hospital admissions due to respiratory diseases. RESULTS: Significant increases in emergency hospital admission due to COPD were found 2 days after dust storm episode. The relative risk of PM(10) for lag 2 days was 1.05 (95% CI: 1.01-1.09) per 10 µg/m(3) . CONCLUSIONS: Dust storms have an adverse effect on emergency hospital admission for COPD in Hong Kong. This also suggests the adverse effect of coarse particles on lung health.

Environmental tobacco smoke exposure and Chinese schoolchildren's respiratory health: a prospective cohort study.

BACKGROUND: Although China is the most coveted cigarette market worldwide, few studies have examined the longitudinal effects of environmental tobacco smoke (ETS) on health. PURPOSE: To examine the relationship between exposure to ETS and respiratory health in Chinese schoolchildren. METHODS: The study subjects included 1718 children, who were never-smokers, aged 10.05±0.86 years and asthma-free at baseline. The children performed spirometric tests in 2006 and 18 months later. Parents reported the children's respiratory symptoms and illnesses, ETS exposure, and other related information by self-administered survey at both assessment points. The data were analyzed in 2010. RESULTS: Significant exposure-response relationships were found between ETS exposure and coughing at night (p for trend<0.001); sneezing (p for trend=0.031); and sneezing with itchy, watery eyes (p for trend=0.006) in the first survey, and coughing at night (p for trend=0.019); phlegm without a cold (p for trend<0.001); and sneezing (p for trend=0.036) in the second survey. Compared with those who reported no ETS exposure in either survey, children who had a high ETS exposure level (>5 cigarettes/day) in either survey had lower growth rates in forced expiratory flow between 25% and 75% of forced vital capacity (FEF(25-75); ß= -0.104, p=0.020) and forced expiratory flow at 25% of forced vital capacity (FEF(25); ß= -0.077, p=0.027). A monotonic exposure-response effect was observed between ETS exposure and the deficits in the growth rate of FEF(25) and FEF(25-75.) CONCLUSIONS: Exposure to ETS increased the risks of respiratory symptoms in Chinese school-aged children and was associated with impaired lung function growth. A dose-response relationship was observed for the latter effect.

Respiratory health and lung function in Chinese restaurant kitchen workers.

OBJECTIVES: To measure air pollutant concentrations in Chinese restaurant kitchens using different stove types and assess their influence on workers' respiratory health. METHODS: 393 kitchen workers from 53 Chinese restaurants were surveyed over 16 months: 115 workers from 21 restaurants using only electric stoves and 278 workers from 32 restaurants using only gas stoves. Workers were interviewed about their respiratory symptoms and had their lung function tested. Concentrations of nitric oxide (NO), nitrogen dioxide (NO(2)), carbon monoxide (CO), carbon dioxide (CO(2)), methane (CH(4)), non-methane hydrocarbons (NMHC), total volatile organic compounds (TVOC) and fine particulate matter (PM(2.5)) were measured using portable monitors and air-bag sampling. Temperature and noise levels were assessed. RESULTS: Median concentrations of NO, NO(2) and CO were 7.4, 1.5 and 1.6 times higher in gas-fuelled kitchens than in electric ones and average concentrations of PM(2.5) and TVOC were 81% and 78% higher, respectively. Differences were smaller for CH(4) and NMHC. Electricity-run kitchens were 4.5°C cooler and 9 dBA less noisy than gas-fuelled ones. Workers using electric cookers had significantly better lung function than their gas-using counterparts and their mean FEV(1) and FVC values were 5.4% and 3.8% higher, respectively, after adjustment for confounders. Wheeze, phlegm, cough and sore throat were more prevalent in workers using gas. The adjusted OR for having phlegm regularly was significantly higher. CONCLUSIONS: The poorer lung function and higher prevalence of respiratory symptoms among workers in gas-fuelled kitchens compared to those in electricity-powered kitchens may be associated with exposure to higher concentrations of toxic air pollutants generated during gas cooking.

A review of statutory medical examinations in Asian-Pacific countries.

BACKGROUND: statutory medical examinations (SME) are practiced worldwide to promote workers' health. We reviewed SME legislation and enforcement in the rapidly industrializing Asia-Pacific, compared these with laws in Europe and America, and identified areas for further development. METHODS: information on SME in 13 Asian-Pacific countries was collected by a questionnaire survey of occupational health (OH) experts from each country, supplemented by a literature and Internet search. RESULTS: SME laws were diverse throughout the Asia-Pacific, and were either selective or comprehensive, depending on the countries' legal systems. Common problems included manpower shortage, high costs and lack of awareness of SME. This resulted in poor compliance, which was broadly associated with the level of socio-economic development. CONCLUSIONS: educating the public on OH issues would address compliance problems, as would the training and efficient deployment of OH professionals. The development of management systems and regional standards would encourage a harmonized approach towards SME.

Effects of ambient air pollution on lung function growth in Chinese schoolchildren.

OBJECTIVE: To evaluate the adverse effect of exposure to air pollution on lung function growth in school-aged children. METHODS: A cohort of 1983 children from three districts in Guangzhou, China was followed-up for 6 months. The children performed pulmonary function tests twice, and their parents reported the child's respiratory symptoms by self-administered questionnaires in both surveys. RESULTS: The annual mean concentrations of air pollutants for the past 5 years for particulate matter less than 10 microns in diameter (PM(10)), nitrogen (NO(2)), and sulfur dioxide (SO(2)) were respectively: 96.1 microg/m(3), 76.0 microg/m(3), and 65.7 microg/m(3) in the highly-polluted district (HPD), 80.3 microg/m(3), 67.6 mug/m(3), and 54.5 microg/m(3) in the moderately-polluted district (MPD), and 80.0 microg/m(3), 48.1 microg/m(3), and 52.2 microg/m(3) in the least-polluted district (LPD). After adjustment for potential confounders, significant deficits were found in the annual growth rates of forced expiratory flows at 25% (FEF(25)), and between 25% and 75% (FEF(25-75)) in boys and FEF(25) in girls (In boys, for FEF(25), -0.136 l/s, p = 0.008 in MPD and -0.153 l/s, p = 0.004 in HPD, respectively; for FEF(25-75), -0.176 l/s, p = 0.013 in MPD and -0.167 l/s, p = 0.021 in HPD, respectively. In girls, for FEF(25), -0.123 l/s, p = 0.043 in HPD), using LPD as the reference. Deficits in the annual growth rate of forced expiratory volume in 1 s (FEV(1)) were also negatively associated with air pollution in boys (-0.063 L, p = 0.032 in HPD). CONCLUSIONS: The study adds more evidence that exposure to air pollution has adverse effects on lung function growth in schoolchildren.

Diurnal temperature range and daily cardiovascular mortalities among the elderly in Hong Kong.

The authors aimed to examine the association between diurnal temperature range (DTR) and daily mortalities due to cardiovascular disease among people aged 65 years and older in Hong Kong, China. The authors used a generalized additive model to regress daily mortalities of the elderly due to cardiovascular disease on DTR and daily concentrations of air pollutants from 1997 to 2002. They also tested the effects of different lag days of DTR on mortality. Results indicate significant associations between cardiovascular mortality and DTR at lag day 1 and at lag days 0-1 to 0-5. The largest effect was at lag days 0-3 (relative risks = 1.017; 95% confidence interval = 1.003-1.031). The authors recommend that special attention be paid to the elderly population to protect them from excessive diurnal variations in temperature.