Prospect of China's ambient air quality standards.

Ambient air quality standards are the core strategic goal of ambient air quality management. Countries worldwide have given importance to research on the development of ambient air quality standards. To understand the history of the development of China's ambient air quality standards, this study analyzed the background associated with all previous formulations and revisions of the standards, classification of functional areas, standard grading, pollutants, and evolution of the standard limits over the past 40 years. The results show that since the initial release of the "Ambient Air Quality Standard" by China in 1982, it has been supplemented once, revised twice, and modified twice. The first ambient air quality standard specified the standard limits of six pollutants commonly found in ambient air. With the development of ambient air quality management, the number of pollutants has increased to ten. Since the release of the "Ambient Air Quality Standards" in 2012, the ambient air quality in China has significantly improved. However, the proportion of cities meeting these standards is still low. At present, China is suitably positioned to make the standards associated with 24 hr SO2 concentrations more stringent such that it meets the values defined in the World Health Organization (WHO) interim target-2 and the WHO air quality guideline (AQG). We further suggested that the SO2 standard should be revised promptly. Simultaneously, regions with a relatively high proportion of cities meeting the standard are encouraged to introduce more stringent interim target limits in due course to manage the local ambient air quality.

Multivariate correlation analysis of bio-accumulation with soil properties and potential health risks of cadmium and lead in rice seeds and cabbage in pollution zones, China.

A total of 475 representative cultivated land and 435 crop samples from 11 provinces of China were collected, and lead and cadmium in 6 polluted areas by wastewater irrigation and metallurgy industry were analyzed. Rice is the major cash crop and staple food of Chinese residents. Cabbage is also a common food in Chinese daily life. Pollution levels and spatial distribution of soil, rice, and cabbage samples were illustrated on the map. In individual or multiple areas, the multivariate correlation of heavy metal's (cadmium and lead) bio-accumulation in two kinds of plants (rice seed and cabbage) and soil properties (pH, cation exchange capacity, and organic matter) was also investigated. Spearman correlation analysis showed that soil pH values and organic matter (OM) had significant effects on the uptake of Cd and Pb in rice seed: the correlation between lg Cd BCF and pH values is -0.148* (p = 0.026), and the correlation between lg Pb BCF and pH values is -0.339** (p = 0.000). The cation exchange capacity (CEC) and pH significantly impact the Cd and Pb uptake in cabbage: the correlation between lg Cd EF and pH values is -0.199* (p = 0.040), and the correlation between lg Pb EF and pH values is -0.203** (p = 0.009). The Cd and Pb bio-concentration factor BCFs of rice and cabbage decreased with the increase of pH, CEC, and OM, except that Pb BCFs increased with the increase of OM in certain areas. The BCF of Cd varied positively from Pb in cabbage, but inversely with Pb in rice significantly at the 0.01 level (two-tailed Spearman correlation analysis). For the first time, the health quotient (HQ) of Cd and Pb in different regions was also calculated and illustrated on the map. In the soil samples of different areas, average HQ values of Cd and Pb in maturity varied from 0.0003-0.0023 to 0.0051-0.0460; average HQ values of immaturity were 0.0011-0.0103 and 0.0222-0.2014. In the rice samples of different areas, average HQ values of Cd and Pb in maturity varied from 0.305-1.360 to 0.027-0.321; average HQ values of immaturity were 0.601-2.678 and 0.053-0.633. Average HQ values orders of magnitude in the cabbage samples of different areas are the same as that of rice samples, and it is 2-4 orders higher than those in soil. Average HQ values of Cd and Pb in maturity varied from 0.152-1.354 to 0.006-0.506; average HQ values of immaturity were 0.510-4.192 and 0.022-0.207. The total HQ values ingested by children were all higher than those in adults. After investigation, it was found that the total HQ value of mature plants was also higher than that of immature plants. The results of this study would be of great help to future soil remediation with similar types.

Comparison of inorganic chemical compositions of atmospheric TSP, PM10 and PM2.5 in northern and southern Chinese coastal cities.

To compare the inorganic chemical compositions of TSP (total suspended particulate), PM10 (particulate matter with an aerodynamic diameter less than 10µm) and PM2.5 (particulate matter with an aerodynamic diameter less than 2.5µm) in southern and northern cities in China, atmospheric particles were synchronously collected in Dalian (the northern city) and Xiamen (the southern city) in spring and autumn of 2004. The mass concentrations, twenty-three elements and nine soluble ions were assessed. The results show that in Dalian, the mass concentrations of Mg, Al, Ca, Mn and Fe in spring were 4.0-10.1, 2.6-8.0, 4.1-12, 1.2-3.6 and 2.9-7.9 times higher, respectively, than those in Xiamen. The dust storm influence is more obvious in Dalian in spring. However, in Xiamen, heavy metals accounted for 13.9%-17.9% of TSP, while heavy metals contributed to 5.5%-9.3% of TSP in Dalian. These concentrations suggest that heavy metal pollution in Xiamen was more serious. In addition, the concentrations of Na+, Cl-, Ca2+ and Mg2+ were higher in Dalian due to the influence of marine aerosol, construction activities and soil dust. The NO3-/SO42- ratios in Dalian (0.25-0.49) were lower than those in Xiamen (0.51-0.62), indicating that the contributions of vehicle emission to particles in Xiamen were higher. Coefficient of divergence values was higher than 0.40, implying that the inorganic chemical composition profiles for the particles of Dalian and Xiamen were quite different from each other.

Chemical composition, mass closure and sources of atmospheric PM10 from industrial sites in Shenzhen, China.

Concentrations of atmospheric PM10 and chemical components (including twenty-one elements, nine ions, organic carbon (OC) and elemental carbon (EC)) were measured at five sites in a heavily industrial region of Shenzhen, China in 2005. Results showed that PM10 concentrations exhibited the highest values at 264 microg/m3 at the site near a harbor with the influence of harbor activities. Sulfur exhibited the highest concentrations (from 2419 to 3995 ng/m3) of all the studied elements, which may be related to the influence of coal used as fuel in this area for industrial plants. This was verified by the high mass percentages of SO4(2-), which accounted for 34.3%-39.7% of the total ions. NO3-/SO4(2-) ratios varied from 0.64-0.71, which implies coal combustion was predominant compared with vehicle emission. The anion/cation ratios range was close to 0.95, indicating anion deficiency in this region. The harbor site showed the highest OC and EC concentrations, with the influence of emission from vessels. Secondary organic carbon accounted for about 22.6%-38.7% of OC, with the highest percentage occurring at the site adjacent to a coal-fired power plant and wood plant. The mass closure model performed well in this heavily industrial region, with significant correlation obtained between chemically determined and gravimetrically measured PM10 mass. The main constituents of PM10 were found to be organic materials (30.9%-69.5%), followed by secondary inorganic aerosol (7.9%-25.0%), crustal materials (6.7%-13.8%), elemental carbon (3.5%-10.8%), sea salt (2.4%-6.2%) and trace elements (2.0%-4.9%) in this heavily industrialized region. Principal component analysis indicated that the main sources for particulate matter in this industrial region were crustal materials and coal/wood combustion, oil combustion, secondary aerosols, industrial processes and vehicle emission.

Using energy expenditure to estimate the minute ventilation and inhaled load of air pollutants: a pilot survey in young Chinese adults.

Existing equations to estimate ventilation (VE) may not represent the Chinese population. The objective is to develop regression equations to predict the basal metabolic rate (BMR) for ventilation estimation. 80 participants underwent the incremental tests on a bicycle ergometer, wearing a fitted facial mask with an airflow sensor connected to the cardiopulmonary gas analyzer, where the energy expenditure, metabolic factors and VE were monitored simultaneously. Linear regression models were established between BMR and body weight, which were used to estimate energy expenditure and VE. Extrapolation of the regression model was evaluated by the five-fold cross-validation. And we also assessed the inhaled load of air pollutants in subgroups at the same exposure levels. Regression models for males and females were BMR (kJ/d) = 107.58 × weight (kg)-172.61 and BMR (kJ/d) = 105.61 × weight (kg)-26.94, respectively. The model showed good fitness between the measured and predicted VE. Differences between the measured and predicted VE of this model are smaller than that of other models. There were significant differences in inhaled load participants in the same exposure concentrations. The regression model showed that weight and BMR are highly correlated and can be used to estimate individual VE.

Short-term exposure to sulfur dioxide and daily mortality in 17 Chinese cities: the China air pollution and health effects study (CAPES).

Sulfur dioxide (SO(2)) is a major air pollutant and has significant impacts upon human health. Few multi-city studies in Asia have examined the acute health effects of SO(2). As part of the China Air Pollution and Health Effects Study (CAPES), this study aimed at investigating the short-term association between SO(2) and daily mortality in 17 Chinese cities. We applied two-stage Bayesian hierarchical models to obtain city-specific and national average estimates for SO(2). In each city, we used Poisson regression models incorporating natural spline smoothing functions to adjust for long-term and seasonal trend of mortality, as well as other time-varying covariates. We examined the associations by age, gender and education status. As a result, the combined analysis showed that an increase of 10 µg/m(3) of two-day moving averaged SO(2) was associated with 0.75% [95% posterior interval (PI), 0.47 to 1.02], 0.83% (0.95% PI, 0.47 to 1.19) and 1.25% (95% PI, 0.78 to 1.73) increase of total, cardiovascular and respiratory mortality, respectively. The effects of SO(2) appeared more evident among the elderly. These associations were generally independent of particles with aerodynamic diameter <10 µm (PM(10)) but did not persist after adjustment for nitrogen dioxide (NO(2)). In conclusions, this largest epidemiologic study of air pollution in China to date suggests that short-term exposure to SO(2) is associated with increased mortality risk; however, these associations may be attributable to SO(2) serving as a surrogate of other substances. Further studies are needed to tackle the independent health effect of SO(2).

[Comparative Analysis of NOx Emission Characteristics of Non-Ultra-Low- and Ultra-Low-Emission Coal-Fired Power Units During the Start-Up Process].

Based on the NOx emission information of 671 coal-fired power units, the NOx emission characteristics of non-ultra-low-emission (non-ULE) and ultra-low-emission (ULE) coal-fired power units during the start-up process were compared and analyzed. The results showed that in the start-up stage of non-ULE units, the exceeding standard rate (ESR) of NOx emission concentration was 81.53%, the average exceeding standard hours (ESHs) was 2.64 h, and the average maximum emission hourly mean concentration (MEHC) was 284.06 mg·m-3. The NOx ESR of ULE units was 79.86%, the average ESHs was 2.52 h, and the average MEHC was 231.61 mg·m-3. There was no significant difference in the ESR and the average ESHs between non-ULE and ULE units, but the difference in the average MEHC was significant. There was no significant difference in the ESR, average ESHs, and average MEHC between different grades of non-ULE units, except that the average MEHC of 300 MW units was significantly lower than that of 200 MW units. There was statistical difference in the ESR, average ESHs, and average MEHC among different grades of ULE units, and 600 MW units performed best in the ESHs control, whereas 1000 MW units performed best in the emission concentration control.

Effect modification of the association between temperature variability and daily cardiovascular mortality by air pollutants in three Chinese cities.

There is limited evidence showing the mortality effects of temperature variability (TV) on cardiovascular diseases. The joint effects between TV and air pollutants are also less well-established. This study aims to assess the effect modification of TV-cardiovascular mortality by air pollutants in three Chinese cities (Beijing, Nanjing and Chengdu). Data of daily mortality, air pollutants and meteorological factors from 2008 to 2011 was collected from each city. TV was calculated as the standard deviation of daily maximum and minimum temperatures over exposure days. The city-specific effect estimates of TV on cardiovascular mortality were calculated using a quasi-Poisson regression model, adjusting for potential confounders (e.g., seasonality and temperature). An interaction term of TV and a three-level air pollutants stratum indicator was included in the models. Effect modifications by air pollutants were assessed by comparing the estimates of TV's effect between pollutant stratums and calculating the corresponding 95% confidential interval of the differences. Multivariate meta-analysis was conducted to obtain the pooled estimates. The data showed that TV was associated with increased risk of cardiovascular mortality, especially for longer TV exposure days (0-8 days, TV08). This association was still observed after adjusting for air pollutants on current day or the previous two days. Stronger estimates were observed in females, but no significant difference between males and females was detected, indicating the absence of evidence of effect modification by gender. Estimates of TV-cardiovascular mortality varied across two season periods (warm and cool season) and age groups, but the evidence of effect modification by age and seasons was absent. Regarding the effect modification of TV-cardiovascular mortality association by air pollutants, a significant effect modification was identified for PM10, but not for NO2 and SO2 in the whole population for all TV exposure days. This finding also persisted in subgroups, specifically in females and the elderly.

Acute Effects of Nitrogen Dioxide on Cardiovascular Mortality in Beijing: An Exploration of Spatial Heterogeneity and the District-specific Predictors.

The exploration of spatial variation and predictors of the effects of nitrogen dioxide (NO2) on fatal health outcomes is still sparse. In a multilevel case-crossover study in Beijing, China, we used mixed Cox proportional hazard model to examine the citywide effects and conditional logistic regression to evaluate the district-specific effects of NO2 on cardiovascular mortality. District-specific predictors that could be related to the spatial pattern of NO2 effects were examined by robust regression models. We found that a 10 µg/m3 increase in daily mean NO2 concentration was associated with a 1.89% [95% confidence interval (CI): 1.33-2.45%], 2.07% (95% CI: 1.23-2.91%) and 1.95% (95% CI: 1.16-2.72%) increase in daily total cardiovascular (lag03), cerebrovascular (lag03) and ischemic heart disease (lag02) mortality, respectively. For spatial variation of NO2 effects across 16 districts, significant effects were only observed in 5, 4 and 2 districts for the above three outcomes, respectively. Generally, NO2 was likely having greater adverse effects on districts with larger population, higher consumption of coal and more civilian vehicles. Our results suggested independent and spatially varied effects of NO2 on total and subcategory cardiovascular mortalities. The identification of districts with higher risk can provide important insights for reducing NO2 related health hazards.

Alternative ozone metrics and daily mortality in Suzhou: the China Air Pollution and Health Effects Study (CAPES).

Controversy remains regarding the relationship between various metrics of ozone (O(3)) and mortality. In China, the largest developing country, there have been few studies investigating the acute effect of O(3) on death. We used three exposure metrics of O(3) (1-hour maximum, maximum 8-hour average and 24-hour average) to examine its short-term association with daily mortality in Suzhou, China. We used a Generalized Additive Model (GAM) with penalized splines to analyze the mortality, O(3), and covariate data. We examined the association by season, age group, sex and educational level. We found that the current level of O(3) in Suzhou is associated with death rates from all causes and cardiovascular diseases. Among various metrics of O(3), maximum 8-hour average and 1-hour maximum concentrations seem to be more strongly associated with increased mortality rate compared to 24-hour average concentrations. Using maximum 8-hour average, an inter-quartile range increase of 2-day average O(3) (lag 01) corresponds to 2.15% (95%CI, 0.36 to 3.93), 4.47% (95%CI, 1.43 to 7.51), -1.85% (95%CI, -6.91 to 3.22) increase in all-cause, cardiovascular, and respiratory mortality, respectively. The associations between O(3) and daily mortality appeared to be more evident in the cool season than in the warm season. In conclusion, maximum 8-hour average and 1-hour maximum concentrations of O(3) are associated with daily mortality in Suzhou. Our analyses strengthen the rationale for further limiting levels of O(3) pollution in the city.

Associations between short-term exposure to nitrogen dioxide and mortality in 17 Chinese cities: the China Air Pollution and Health Effects Study (CAPES).

Few multi-city studies in Asian developing countries have examined the acute health effects of ambient nitrogen dioxide (NO(2)). In the China Air Pollution and Health Effects Study (CAPES), we investigated the short-term association between NO(2) and mortality in 17 Chinese cities. We applied two-stage Bayesian hierarchical models to obtain city-specific and national average estimates for NO(2). In each city, we used Poisson regression models incorporating natural spline smoothing functions to adjust for long-term and seasonal trend of mortality, as well as other time-varying covariates. We examined the associations by age, gender and education status. We combined the individual-city estimates of the concentration-response curves to get an overall NO(2)-mortality association in China. The averaged daily concentrations of NO(2) in the 17 Chinese cities ranged from 26 µg/m(3) to 67 µg/m(3). In the combined analysis, a 10-µg/m(3) increase in two-day moving averaged NO(2) was associated with a 1.63% [95% posterior interval (PI), 1.09 to 2.17], 1.80% (95% PI, 1.00 to 2.59) and 2.52% (95% PI, 1.44 to 3.59) increase of total, cardiovascular, and respiratory mortality, respectively. These associations remained significant after adjustment for ambient particles or sulfur dioxide (SO(2)). Older people appeared to be more vulnerable to NO(2) exposure. The combined concentration-response curves indicated a linear association. Conclusively, this largest epidemiologic study of NO(2) in Asian developing countries to date suggests that short-term exposure to NO(2) is associated with increased mortality risk.

[Health risk assessment of heavy metals in drinking water based on field measurement of exposure factors of Chinese people].

This study was carried out in Biyang County, located in the junction of Yangtze river and Huaihe river. Drinking water samples of 20 sites in urban and rural areas in this county were collected to measure 14 heavy metals by ICP/MS. About 2 500 subjects with different age and sex were selected to measure exposure factors. Time-activity of drinking water by ingestion and dermal contact of each individual subject during the last three days were kept in dairy in detail by questionnaires. Intake of drinking water from direct and indirect consumption of water and time duration of dermal contact to water in each individual subject were kept in record based on real time measurements. Human health risks were assessed and sensitivity of exposure factors and uncertainty of risks were also analyzed. The results showed that the average drinking water intake rate of male and female are 2276 mL/d, 2265 mL/d in urban adults and 2464 mL/d, 2170 mL/d in rural adults respectively. Body surface area of male and female are 1.806 m2, 1.641 m2 in urban adults and 1.747 m2, 1.617 m2 in rural adults respectively. The contents of 14 heavy metals in this study area are all below the national drinking water standards. Cancer risks from exposure to As are ranged from 2.5 x 10(-6) to 5.2 x 10(-6) through ingestion and 1.1 x 10(-7) to 2.3 x 10(-7) through dermal exposure. Non-cancer risks are ranged from 2.1 x 10(-7) to 1.7 x 10(-6) through ingestion and 1.0 x 10(-8) to 6.0 x 10(-8) through dermal exposure. Non-cancer risks in rural population are 2.1 times to 5.6 times to the risks in urban populations. However all the risks are below the acceptable level. The sensitivity of various exposure factors including drinking water intake rate, dermal exposure time and body surface area are 71.5%. This indicates that exposure factors play a very important role in health risk assessment. Health risks in this research based on real measurement of exposure factors are about 0.94 time to 6.33 times higher than the risks based on the references of the data from the exposure factors handbooks in other countries. This study showed that the accuracy of health risk assessment could be improved a lot by the real measurements of exposure factors. Attentions should be attached to exposure factor investigation to decrease uncertainty of health risk assessment.