Estimated Acute Effects of Ambient Ozone and Nitrogen Dioxide on Mortality in the Pearl River Delta of Southern China

Background and objectives: Epidemiologic studies have attributed adverse health effects to air pollution; however, controversy remains regarding the relationship between ambient oxidants [ozone (O3) and nitrogen dioxide (NO2)] and mortality, especially in Asia. We conducted a four-city time-series study to investigate acute effects of O3 and NO2 in the Pearl River Delta (PRD) of southern China, using data from 2006 through 2008

Assessment of motor vehicle emission control policies using Model-3/CMAQ model for the Pearl River Delta region, China

In recent decades, the Pearl River Delta (PRO) region located in south China has been experiencing severe air pollution, arising from the rapid increase in industry and motor vehicles. As a major contributing source to VOCs and NO(x) emissions, control of vehicular emissions plays a very important role in improving regional air quality. By taking 2015 as a target year, this paper assessed the impacts of five possible motor vehicle emission control measures and a combined policy scenario on ambient air quality in the PRD region, with the use of the Model-3/CMAQ (Community Multi-scale Air Quality) model. The results show: (1) an overall decreasing pattern in SO(2), NO(2) and PM(10) concentrations was found in central-south metropolitan areas of the PRO region for all measures, but increased O(3) concentrations may occur in these areas as well. The exception to this is that a slight decrease was observed for the cases of motorcycle restriction and introduction of HEV: (2) upgrading to National IV emission standards is the most effective individual measure and can reduce daily averaged NO(2) and PM(10) concentrations by 11.7 ppbV and 21.3 mu g m(-3), respectively; but involves an increase (at maximum) of 10.3ppbV in O(3) concentration. Evaluation of the combined scenario indicates that solely controlling motor vehicle emissions is not sufficient to improve PRO regional air quality significantly. O(3) and PM(10) concentrations under the same VOC/NO(x) reduction ratios exhibit differently at different locations, suggesting that integrated and location-specific pollution control strategies, considering co-control of multi-pollutants, are needed in this region in order to decrease primary and secondary pollutant concentrations simultaneously. (C) 2011 Elsevier Ltd. All rights reserved

A refined 2010-based VOC emission inventory and its improvement on modeling regional ozone in the Pearl River Delta Region, China

Accurate and gridded VOC emission inventories are important for improving regional air quality model performance. In this study, a four-level VOC emission source categorization system was proposed. A 2010-based gridded Pearl River Delta (PRD) regional VOC emission inventory was developed with more comprehensive source coverage, latest emission factors, and updated activity data. The total anthropogenic VOC emission was estimated to be about 117.4 x 10(4) t, in which on-road mobile source shared the largest contribution, followed by industrial solvent use and industrial processes sources. Among the industrial solvent use source, furniture manufacturing and shoemaking were major VOC emission contributors. The spatial surrogates of VOC emission were updated for major VOC sources such as industrial sectors and gas stations. Subsector-based temporal characteristics were investigated and their temporal variations were characterized. The impacts of updated VOC emission estimates and spatial surrogates were evaluated by modeling O-3 concentration in the PRD region in the July and October of 2010, respectively. The results indicated that both updated emission estimates and spatial allocations can effectively reduce model bias on O-3 simulation. Further efforts should be made on the refinement of source classification, comprehensive collection of activity data, and spatial-temporal surrogates in order to reduce uncertainty in emission inventory and improve model performance. (C) 2015 Elsevier B.V. All rights reserved

Particle Growth and Variation of Cloud Condensation Nucleus Activity on Polluted Days with New Particle Formation: A Case Study for Regional Air Pollution in the PRD Region, China

New particle formation (NPF) events on polluted days at a regional supersite in the Pearl River Delta (PRD) region and its impact on the abundance and properties of cloud condensation nuclei (CCN) were investigated. Nucleation and subsequent significant growth of nanoparticles on a regional scale was observed and representative events on 2 and 6 October 2013 were chosen in this study. The measurements showed that the primary components of the particles were sulfate, ammonium, and organics as they were added continuously to secondary aerosol mass and that particles show inversion from growth to shrink if the particles comprise primarily of organics due to evaporation of semi-volatile species under favorable meteorological conditions. The effective hygroscopicity parameter. of fine particles on 2 October composed of sulfate, nitrate and ammonium (kappa = 0.26-0.42) was larger than that of fine particles on 6 October containing more organics (kappa = 0.19-0.36). Particles in the nucleation mode were observed to grow rapidly to the CCN sizes and dominate the CCN number concentrations at a water vapor supersaturation (S) over 0.46%. At an S range of 0.26-0.86%, the CCN number concentrations reached maximum values of (1.3-2.6) x 10(4) cm(-3) after the NPF event on 2 October. The sulfate component in the particles was found to increase significantly, about 50% higher than that before NPF. Results from events on 6 October showed a significant increase of the organic component and the CCN number concentrations after the NPF event were comparable or slightly lower than those before the event. Nevertheless, the average CCN number concentrations scaled with EC mass concentration with S over 0.46% in the daytime of 2 and 6 October were significantly higher than those on a non-NPF event day.National Natural Science Foundation of China [41303075, U1301234]; major national scientific instrument and equipment development project [2013YQ060569]; Pearl River New Star project on science and technology in Guangzhou [201506010079]SCI(E)[email protected]

Science policy interplay: Air quality management in the Pearl River Delta region and Hong Kong

The information provided by the scientific studies and control measures implemented in the Pearl River Delta (PRD) region of China reveals that tremendous progress has been made in the understanding of regional air pollution issues and the deployment of mitigation measures for alleviating these problems. Given the unparalleled rapid economic growth in the PRD over the past two decades, such progress was only made possible by strong, science-based support and the partnerships between government and research institutions in the region and overseas. Researchers from these partnership programs and related studies have deployed cutting-edge expertise and experience in various crucial mainland China and mainland China/Hong Kong-level projects. China recognizes the importance of protecting the environment and cleaning up the air in the pursuit of sustainable growth and economic development. To avoid falling into a cycle of event-driven clean-up efforts, China has recently taken a major step and updated the national ambient air quality standards. Clearly, China is implementing an increasing number of evidence-based policies to address air pollution problems. Thus, to bring a fresh impetus at a national level, the PRD must maintain and augment the Hong Kong-mainland collaborative momentum, inducing a "whole-China" effort to clean up air pollution. To strengthen the science-based support system and ensure continuous and concerted effort in implementing the regional multi-pollutant control strategy, there must be an over-arching and integral Hong Kong-Guangdong science consortium framework supporting the formulation of regional policy and control measures built on common goals under the "one country, two systems" principle. The "PRD Approach" of the air quality management regime reflected regional cooperative efforts in synchronous air pollutant control, catalyzed the crucial role of information disclosure and subtly transformed the air quality management approach to overcome the nation's new air pollution challenges. (C) 2013 Elsevier Ltd. All rights reserved

Systematic review of Chinese studies of short-term exposure to air pollution and daily mortality

Health effects attributable to air pollution exposure in Chinese population have been least understood. The authors conducted a meta-analysis on 33 time-series and case-crossover studies conducted in China to assess mortality effects of short-term exposure to particulate matter with aerodynamic diameters less than 10 and 2.5 mu m (PM10 and PM2.5), sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O-3) and carbon monoxide (CO). Significant associations between air pollution exposure and increased mortality risks were observed in the pooled estimates for all pollutants of interest. In specific, each 10 mu g/m(3) increase in PM2.5 was askwiated with a 0.38% (95% Confidence Interval, CI: 0.31, 0.45) increase in total mortality, a 0.51% (95% CI: 0.30, 0.73) in respiratory mortality, and a 0.44% (95% CI: 033, 0.54) in cardiovascular mortality. When current annual PM2.5 levels in mega-Chinese cities to be reduced to the WHO Air Quality Guideline (AQG) of 10 mu g/m(3), mortality attributable to short-term exposure to PM2.5 could be reduced by 2.7%, 1.7%, 2.3%, and 62% in Beijing, Shanghai, Guangzhou and Xi'an, respectively. The authors recommend future studies on the nature of air pollution concentration and health effect relationships in Chinese population to support setting stringent air quality standards to improve public health. (C) 2013 Elsevier Ltd. All rights reserved.Environmental SciencesSCI(E)EI26REVIEW100-1115

Reconstructed Light Extinction Coefficients of Fine Particulate Matter in Rural Guangzhou, Southern China

A one-year campaign was conducted to collected PM2.5 samples in the rural area of Guangzhou, the largest megacity in South China, from March 2012 to February 2013. Mass concentration of PM2.5, carbonaceous fractions (i.e., organic carbon (OC) and elemental carbon (EC)) and 6 water-soluble ions were analyzed. Light extinction coefficient (b(ext)) of fine particulate matter was reconstructed using the revised IMPROVE formula at the site. The reconstructed b(ext) was compared with the measured b(ext) converted from visibility. A good correlation was obtained between the two sets of b(ext) with a coefficient of determination (R-2) of 0.61 and a slope of 0.99. The average reconstructed b(ext) in the study was 253.7 +/- 162.9 Mm(-1). The seasonal reconstructed b(ext) was in the order of autumn (319.4 +/- 207.2 Mm(-1)) > winter (269.6 +/- 175.5 Mm(-1)) > summer (219.0 +/- 129.3 Mm(-1)) > spring (193.3 +/- 94.9 Mm(-1)). (NH4)(2)SO4 (AS) made a dominant contribution to the light extinction budget, accounting for 61.3% (155.6 +/- 108.5 Mm(-1)) annually, with highest in autumn (68.0%) and lowest in winter (55.2%). Organic matter (OM) was the second largest contributor accounting for 20.5% (52.2 +/- 42.7 Mm(-1)) with highest in winter (23.4%) and lowest in spring (18.0%). The relationship between reconstructed b(ext) and measured bext was investigated under the influence of seasonality, visibility and PM2.5 concentration. We found that b(ext) could be reconstructed using revised IMPROVE formula in high PM2.5 days (threshold value of similar to 60 mu g m(-3)). On other hand, the performance of formula was unsatisfactory for b(ext) reconstruction of in low PM2.5 days, when meteorological conditions could have significant impact on visibility

Regional ozone pollution and key controlling factors of photochemical ozone production in Pearl River Delta during summer time

An intensive field campaign including measurements from the environmental monitoring network and from two super sites took place in the Pearl River Delta region in summer 2006. Using routinely measured O3 and NOx concentrations, the spatial and temporal variation of O3 and of the total oxidant concentrations was characterized. According to the spatial variability of NO2/NO, the two super sites were found to be representative of polluted urban and downwind suburban conditions. In addition, both sites were located in high O3 regions. In-depth diagnostic of photochemical ozone production processes and their key controlling factors are achieved with an observation-based model (OBM) to gain regional perspectives. Budget analysis and sensitivity model runs show that aldehyde and HONO chemistry had significant impacts on local photochemical ozone production rates. The analysis of calculated Relative Incremental Reactivities shows that photochemical ozone production rates are mainly sensitive to anthropogenic hydrocarbons (HCs) in the polluted urban areas. In the suburban areas, sensitivity to nitrogen oxide (NO) concentrations dominated. Key anthropogenic HCs in both areas are alkenes and aromatics. Significant differences of ozone production efficiencies are identified between the urban and suburban regions, consistent with the OBM diagnosed results