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 SO2concentrations 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 SO2standard 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.

Are current Chinese national ambient air quality standards on 24-hour averages for particulate matter sufficient to protect public health？

With rapid economic development and urbanization in recent decades, China has experienced the worsening of ambient air quality. For better air quality management to protect human health, Chinese government revised national ambient air quality standards （NAAQS） for particulate matter （PM） in 2012 （GB3095-2012）. To assess the effectiveness of current NAAQS for PM on public health in Chinese population, we conducted a meta- analysis on published studies examining the mortality risk of short-term exposure to PM with aerodynamic diameters less than 10 and 2.5μm （PM10 and PM2.5） in China. The reported 24-hour concentrations of PM10 and PM2.5 in studies ranged from 43.5 to 150.1 μg/m^3 and 37.5 to 176.7 μg/m^3. In the pooled excess, mortality risk estimates of short-term exposure to PM. In specific, per 10 μg/m^3 increase in PM10, we observed increases of 0.40% （95%CI： 0.33%, 0.47%）, 0.57% （95%CI： 0.44%, 0.70%） and 0.49% （95%CI： 0.40%, 0.58%） in total, respiratory and cardiovascular mortality, per 10/μg/m^3 increase in PM2.5, we observed increases of 0.51% （95% CI： 0.38%, 0.63%）, 0.62% （95%CI： 0.52%, 0.73%） and 0.75% （95%CI： 0.54%, 0.95%） in total, respiratory and cardiovascular mortality. Finally, we derived 125 μg/m^3 for PM10 and 62.5 μg/ m^3 for PM2.5 as 24-hour recommendation values based on the pooled estimates. Our results indicated that current Chinese NAAQS for PM could be sufficient in mitigating the excess mortality risk from short-term exposure to ambient PM. However, future research on long-term exposure cohort studies in Chinese population is also essential in revising annual averages for PM in Chinese NAAQS.

Atmospheric Environmental Capacity of S_2 in Winter over Lanzhou in China:A Case Study

The total emission control method based on atmospheric environmental capacity is the most effective in air pollution mitigation. The atmospheric environmental capacities of SO2 on representative days over Lanzhou are estimated using the numerical models RAMS, HYPACT and a linear programming model, according to the national ambient air quality standard of China （NAAQSCHN）. The results show that the fields of meteorological elements and SO2 simulated by the models agree reasonably well with observations. The atmospheric environmental capacity of SO2 over Lanzhou is around 111.7 × 10^3 kg d^-1, and in order to meet the air quality level Ⅱ of the NAAQSCHN, SO2 emissions need to be reduced by 20%.

Design and demonstration of a next-generation air quality attainment assessment system for PM_(2.5)and O_3

Due to the increasingly stringent standards, it is important to assess whether the proposed emission reduction will result in ambient concentrations that meet the standards. The Software for Model Attainment Test-Community Edition （SMAT-CE） is developed for demonstrating attainment of air quality standards of O3 and PM2.5. SMAT-CE improves computational efficiency and provides a number of advanced visualization and analytical functionalities on an integrated GIS platform. SMAT-CE incorporates historical measurements of air quality parameters and simulated air pollutant concentrations under a number of emission inventory scenarios to project the level of compliance to air quality standards in a targeted future year. An application case study of the software based on the U.S. National Ambient Air Quality Standards （NAAQS） shows that SMAT-CE is capable of demonstrating the air quality attainment of annual PM2.5 and 8-hour O3 for a proposed emission control policy.

Spatial and temporal variation of particulate matter and gaseous pollutants in 26 cities in China

O3 and PM2.5 were introduced into the newly revised air quality standard system in February 2012, representing a milestone in the history of air pollution control, and China＇s urban air quality will be evaluated using six factors （SO2, NO2, O3, CO, PM2.5 and PM10） from the beginning of 2013. To achieve the new air quality standard, it is extremely important to have a primary understanding of the current pollution status in various cities. The spatial and temporal variations of the air pollutants were investigated in 26 pilot cities in China from August 2011 to February 2012, just before the new standard was executed. Hourly averaged SO2, NO2 and PMlo were observed in 26 cities, and the pollutants O3, CO and PM2.5 were measured in 15 of the 26 cities. The concentrations of SO2 and CO were much higher in the cities in north China than those in the south. As for O3 and NO2, however, there was no significant difference between northern and southern cities. Fine particles were found to account for a large proportion of airborne particles, with the ratio of PM2.5 to PMI0 ranging from 55% to 77%. The concentrations of PM2.5 （57.5 μg/m3） and PMlo （91.2 μg/m3） were much higher than the values （PM2.5：11.2μg/m3; PMI0：35.6 μg/m3） recommended by the World Health Organization. The attainment of the new urban air quality standard in the investigated cities is decreased by 20% in comparison with the older standard without considering O3, CO and PM2.5, suggesting a great challenge in urban air quality improvement, and more efforts will to be taken to control air pollution in China.