10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
High Sectorially Resolved Inventories to Evaluate Air Quality Trends in China
SHU TAO, Peking University
Abstract Number: 1726 Working Group: Invited by Conference Chair
Abstract Based on a set of high-sectorially resolved air pollutant emission inventories, impacts of socioeconomic transition and regulations on air pollution allevation in China were evaluated. Three case studies are presented to illustrate the lessons learned: 1) Impact of rural residential energy transition on air pollution and health; 2) Health effects of banning beehive coke ovens; and 3) Effectiveness of recent emission reduction efforts of major cities.
Rural household energy use is an important source of emission of air pollutants in China. However, the magnitude of rural household energy use, especially during the transition from use of solid fuels to clean fuels and electricity, has not been well quantified. To collect first-hand data on rural energy consumption and transition, the nationwide data were collected from a 34,489-household energy mix survey and a 1670-household fuel weighing campaign. It was found that the previous information from the International Energy Agency (IEA) and Food and Agriculture Organization (FAO) had significant errors. Consumption of wood and crop residue decreased by 61% and 57%, respectively, from 1992 to 2012 in rural China, much higher than the 15% and 8% reported by IEA and FAO. The fast energy transition that China is experiencing, primarily driven by an increase in income, has resulted in a significant emission reduction and health-climate co-benefit. It was estimated that the relative contribution of the rural residential sector to exposure to ambient PM2.5 decreased from 18±13 to 14±10 mg/m3, that premature deaths decreased from 390 (360-420 as semi-quartile range) to 220 (200-250) thousand, and climate forces decreased from 0.057 ± 0.016 to 0.031 ± 0.008 W/m2 during a period from 1992 to 2012, respectively. Still, the dependency of rural residents in northern China on traditional biomass and coal for heating is one of the most important factors contributing to ambient PM2.5 associated health outcomes.
Althoiugh beehive coke ovens, which was a major souce of benzo[a]pyrene, were banned by the Coal Law in 1996, they were not totally eliminated till 2011. The heath effects of historical beehive coke oven operation, the health benefits of the ban, and the adverse impacts of the poor implementation of the ban were quantitatively evaluated. Historical emissions of benzo[a]pyrene were re-constructed based on satellite images and used to model atmospheric transport, non-occupational population exposure, and induced lung cancer risk. It was demonstrated that more than 20% of the benzo[a]pyrene in ambient air was from beehive coke production in the peak production year. The cumulative non-occupational excess lung cancer cases associated with benzo[a]pyrene from beehive coke ovens was 3,500 (±1,500) from 1982 to 2015. If there was no ban, the cases would be as high as 9,290 (±4,300), indicating significant health benefits of the Coal Law. If the ban had been fully implemented immediately after the law was enforced in 1996, the cumulative cases would be 1,500 (±620), showing the importance of implementing the law.
Measures have been taken to reduce PM2.5 concentrations in China. However, the effectiveness of these measures has not been evaluated. To do so, confunding effects of meteorological factos have to be eliminated. A novel approach is applied to address this issue by individually quantifying the influences of emissions and meteorological effects on PM2.5 concentrations.Ambient PM2.5 concentrations from 1980 to 2014 were modeled subjected to three conditional scenarios that included a realistic situation, fixed emissions, and fixed meteorology. The differences among the model outputs were analyzed to quantify the relative contributions of emissions and meteorological factors. The output from the fixed-meteorology simulation was applied to develop regression models to predict emissions-driven PM2.5 concentrations, whereas the output from the fixed-emission simulation was adopted to establish probability functions to characterize the meteorological factor-induced PM2.5 fluctuations. The models were used to assess the effectiveness of the emissions reduction efforts implemented in major Chinese cities. It is demonstrated that the current decreasing PM2.5 trends in major Chinese cities are primarily driven by mitigation efforts, whereas the rebounds occasionally occurred due to the meteorological effects. Targeted emission reduction objectives of majority of cities have been exceeded so far. If the targeted emissions reduction goals can be fully achieved, the annual mean PM2.5 concentrations in 73% (55-89% as the 95% uncertainty interval) of the 190 major cities would reach the national standard of 35 μg/m3 by 2030, and the percentage would be 94% (85-98%) if 50% extra efforts are made.