THE CAMPAIGN ONATMOSPHERIC AEROSOLRESEARCH NETWORKOF CHINACARE-CHINA

Abstract Based on a network of field stations belonging to the Chinese Academy of Sciences (CAS), the Campaign on Atmospheric Aerosol Research network of China (CARE-China) was recently established as the country’s first monitoring network for the study of the spatiotemporal distribution of aerosol physical characteristics, chemical components, and optical properties, as well as aerosol gaseous precursors. The network comprises 36 stations in total and adopts a unified approach in terms of the instrumentation, experimental standards, and data specifications. This ongoing project is intended to provide an integrated research platform to monitor online PM2.5 concentrations, nine-size aerosol concentrations and chemical component distributions, nine-size secondary organic aerosol (SOA) component distributions, gaseous precursor concentrations (including SO2, NOx, CO, O3, and VOCs), and aerosol optical properties. The data will be used to identify the sources of regional aerosols, the relative contributions from nature and anthropogenic emissions, the formation of secondary aerosols, and the effects of aerosol component distributions on aerosol optical properties. The results will reduce the levels of uncertainty involved in the quantitative assessment of aerosol effects on regional climate and environmental changes and ultimately provide insight into how to mitigate anthropogenic aerosol emissions in China. The present paper provides a detailed description of the instrumentation, methodologies, and experimental procedures used across the network, as well as a case study of observations taken from one station and the distribution of main components of aerosol over China during 2012.</jats:p

Measuring OVOCs and VOCs by PTR-MS in an urban roadsidemicroenvironment of Hong Kong: relative humidity andtemperature dependence, and field intercomparisons

Volatile organic compound (VOC) control is an important issue of air quality management in Hong Kong because ozone formation is generally VOC limited. Several oxygenated volatile organic compound (OVOC) and VOC measurement techniques &ndash; namely, (1)&nbsp;offline 2,4-dinitrophenylhydrazine&nbsp;(DNPH) cartridge sampling followed by high-performance liquid chromatography&nbsp;(HPLC) analysis; (2)&nbsp;online gas chromatography&nbsp;(GC) with flame ionization detection&nbsp;(FID); and (3)&nbsp;offline canister sampling followed by GC with mass spectrometer detection&nbsp;(MSD), FID, and electron capture detection&nbsp;(ECD) &ndash; were applied during this study. For the first time, the proton transfer reaction&ndash;mass spectrometry&nbsp;(PTR-MS) technique was also introduced to measured OVOCs and VOCs in an urban roadside area of Hong Kong. The integrated effect of ambient relative humidity (RH) and temperature ( T ) on formaldehyde measurements by PTR-MS was explored in this study. A Poly&nbsp;2-D regression was found to be the best nonlinear surface simulation ( r  &thinsp;=&thinsp; 0.97) of the experimental reaction rate coefficient ratio, ambient RH, and T for formaldehyde measurement. This correction method was found to be better than correcting formaldehyde concentrations directly via the absolute humidity of inlet sample, based on a 2-year field sampling campaign at Mong Kok (MK) in Hong Kong. For OVOC species, formaldehyde, acetaldehyde, acetone, and MEK showed good agreements between PTR-MS and DNPH-HPLC with slopes of 1.00, 1.10, 0.76, and 0.88, respectively, and correlation coefficients of 0.79, 0.75, 0.60, and 0.93, respectively. Overall, fair agreements were found between PTR-MS and online GC-FID for benzene (slope &thinsp;=&thinsp; 1.23, r  &thinsp;=&thinsp; 0.95), toluene (slope &thinsp;=&thinsp; 1.01, r  &thinsp;=&thinsp; 0.96) and C 2 -benzenes (slope &thinsp;=&thinsp; 1.02, r  &thinsp;=&thinsp; 0.96) after correcting benzene and C 2 -benzenes levels which could be affected by fragments formed from ethylbenzene. For the intercomparisons between PTR-MS and offline canister measurements by GC-MSD/FID/ECD, benzene showed good agreement, with a slope of 1.05 ( r  &thinsp;=&thinsp; 0.62), though PTR-MS had lower values for toluene and C 2 -benzenes with slopes of 0.78 ( r  &thinsp;=&thinsp; 0.96) and 0.67 ( r  &thinsp;=&thinsp; 0.92), respectively. All in all, the PTR-MS instrument is suitable for OVOC and VOC measurements in urban roadside areas.</p

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&#39;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.</p