EAST ASIAN AIR POLLUTION - IMPACTS ON AIR QUALITY, PREMATURE MORTALITY AND RADIATIVE FORCING

Evaluating impacts of air pollution in China on local public health:  Implications for future air pollution and energy policies in China
Research team:  Denise Mauzerall, Xiaoping Wang (doctoral student), and collaborators

To establish the link between energy consumption and technologies, air pollution concentrations, and resulting impacts on public health in eastern China we used Zaozhuang, a city in eastern China heavily dependent on coal, as a case study to quantify the impacts that air pollution in eastern China had on public health in 2000 and the benefits in improved air quality and health that could be obtained by 2020, relative to business-as-usual (BAU), through the implementation of best available emission control technology (BACT) and advanced coal gasification technologies (ACGT).  We made significant advances over previous work by first developing a highly spatially and temporally resolved emission inventory for eastern China for 2000 and for three 2020 scenarios (Wang, Mauzerall et al., 2005) and by using use a sophisticated regional air quality modeling system (Models3 - CMAQ/MM5/SMOKE) to simulate pollution levels in 2000 and 2020 over eastern China (Wang and Mauzerall, 2006).  Uncertainties in emissions are an obstacle to accurately predicting air pollution concentrations and impacts.  We developed an emission inventory that includes both sector specific anthropogenic and biogenic emissions for 2000 and three emission scenarios for 2020 [Wang, Mauzerall et al., 2005] thus permitting an evaluation of the benefits of the use of different energy and air pollution control technologies.  We evaluated the 2000 inventory by using a regional model, Models3, to simulate ambient air pollution concentrations in eastern China and compared simulated pollutant concentrations with available measurements. Our emission estimates for year 2000 are higher than other studies for most pollutants, although our inventory evaluation suggests we likely still underestimated actual emissions.

We then used an integrated assessment approach which combined the emission inventories and air quality modeling with engineering, epidemiology, and economics, to evaluate the monetary benefit of improved air quality on health. We found that total health damages due to year 2000 anthropogenic emissions from Zaozhuang, using the ‘‘willingness-to-pay’’ metric, was equivalent to 10% of Zaozhuang’s GDP (Wang and Mauzerall, 2006). If all health damages resulting from coal use were internalized in the market price of coal, the year 2000 price would have more than tripled. With no new air pollution controls implemented between 2000 and 2020 but with projected increases in energy use, we projected health damages from air pollution exposure would be equivalent to 16% of Zaozhuang’s projected 2020 GDP.  BACT and ACGT could reduce the potential health damage of air pollution in 2020 to 13% and 8% of projected GDP, respectively. Despite significant uncertainty associated with each element of the integrated assessment approach, we demonstrate that substantial benefits to public health could be achieved in this region of eastern China through the use of additional pollution controls and particularly from the use of advanced coal gasification technology (which would also permit the sequestration of carbon dioxide). Without such controls, the impacts of air pollution on public health, considerable in year 2000, will increase substantially by 2020.

Publications
Wang, X, D. L Mauzerall, Y. Hu, A. G. Russell, E. D. Larson, J-H. Woo, D. G. Streets, A. Guenther, A High-Resolution Emission Inventory for Eastern China in 2000 and Three Scenarios for 2020, Atmospheric Environment, Volume 39: No. 32, 5917-5933, October 2005.

Wang, X. and D. L. Mauzerall, Evaluating Impacts of Air Pollution in China on Public Health: Implications for Future Air Pollution and Energy Policies, Atmospheric Environment, Volume 40, Issue 9, Pages 1706-1721, 2006.

Present and Potential future contributions of aerosols from China to global air quality, premature mortality and radiative forcing.
Research team:  Denise Mauzerall, Eri Saikawa (doctoral student), and GFDL collaborators

In this project we expanded on our earlier research to examine implications of present and potential future emissions of sulfate, black and organic carbon aerosols from China on global air quality, resulting premature mortalities both within China and globally, and in particular, the implications of possible future emissions on radiative forcing and climate (Saikawa et al., 2009).  This is the first time that health and radiative impacts of the present and potential future emission of air pollutants have been examined in a consistent fashion.

Aerosols are harmful to human health and have both direct and indirect effects on climate. China is a major contributor to global emissions of sulfur dioxide (SO2), a sulfate (SO4^2-) precursor, organic carbon (OC), and black carbon (BC) aerosols. Although increasingly examined, the effect of present and potential future levels of these emissions on global premature mortality and climate change has not been well quantified. Through both direct radiative effects and indirect effects on clouds, SO4^2- and OC exert negative radiative forcing (cooling) while BC exerts positive forcing (warming). We analyze the effect of China’s emissions of SO2, SO4^2-, OC and BC in 2000 and for three emission scenarios in 2030 on global surface aerosol concentrations, premature mortality, and radiative forcing (RF). Using sophisticated global models of chemical transport (MOZART-2) and radiative transfer (GFDL RTM), and combining simulation results with gridded population data, mortality rates, and concentration–response relationships from the epidemiological literature, we estimate the contribution of Chinese aerosols to global annual premature mortality and to RF in 2000 and 2030. In 2000, we estimate these aerosols cause approximately 470,000 premature deaths in China and an additional 30,000 deaths globally. In 2030, aggressive emission controls lead to a 50% reduction in premature deaths from the 2000 level in China and 10,000 elsewhere, while under a high emissions scenario premature deaths increase 50% from the 2000 level to 720,000 in China and to 40,000 elsewhere. Because the negative RF from SO4^2- and OC is larger than the positive forcing from BC, Chinese aerosols lead to global net direct RF of -74mWm^-2 in 2000 and between -15 and -97 mWm^-2 in 2030 depending on the emissions scenario. Our analysis indicates that increased effort to reduce greenhouse gases is essential to address climate change as reduction of aerosols from China may result in significant loss of net negative radiative forcing.

Publication

Saikawa, E., V. Naik, L.W. Horowitz, J. Liu, D.L. Mauzerall, Present and potential future contributions of sulfate, black and organic carbon aerosols from China to global air quality, premature mortality and radiative forcing, Atmospheric Environment, 43 (2009) 2814–2822, 2009.

Environmental health in China:  progress towards clean air and safe water
Team: Denise Mauzerall, Junfeng Zhang (University of Medicine and Dentistry of NJ, School of Public Health), Zhu Tong (Beijing University), Majiid Ezzati (Harvard School of Public Health), Justin Remais (Emory)

Although economic growth from industrialization has improved health and quality of life indicators in China, it has also increased the release of chemical toxins and greenhouse gases into the environment with severe effects on health.  Facing the overlap of traditional, modern, and emerging environmental dilemmas, we found that China has committed substantial resources to environmental improvement. The country has the opportunity to address its national environmental health challenges and to assume a central role in the international effort to improve the global environment.

Publication

Zhang, J, DL Mauzerall, T Zhu, S Liang, M Ezzati, J Remais. Environmental health in China: challenges to achieving clean air and safe water, The Lancet, 375: 1110–19,2010.

Impact of emission reductions, regional transport and precipitation on air quality during the 2008 Beijing summer Olympics.
Research Team:  Denise Mauzerall, Yan Zhang (doctoral student), James Smith (CEE prof.), Zifa Wang (Chinese Academy of Sciences), and collaborators.

This study is examining the influence of emission reduction measures, regional transport and precipitation on air quality during the 2008 Beijing summer Olympics.   Two sets of numerical simulations were performed with WRF-Chem, one using BAU emissions (standard summer emissions in previous years) and one using a reduced emission scenario (RES) representing reduced emissions during the summer of the Olympics.  The model was evaluated with available observations and differences between the two simulations were analyzed.  Preliminary conclusions include that emission reduction efforts, including shutting down factories, halting construction, and reducing vehicle traffic during the Olympics lead to a daily reduction in central Beijing surface emissions of SO2 by over 5%, NH3 by over 10%, NOx and CO  by over 30%, and PM2.5 and PM10 by over 70%.  The average surface concentration of SO2 was reduced by over 5%, NOx by 40%, CO by 30%, and PM2.5 and PM10 by over 10%.  Due to increased O3 production efficiency resulting from decreased NOx, O3 increased by nearly 15% in central Beijing during the Olympics. The lower reduction in surface concentration of PM (~10%) compared to the reduction in surface emissions (over 70%) was linked to regional transport of pollutants from the surrounding region where emission reductions were minimal (Zhang, Mauzerall et al., manuscript in preparation). 

Impact of Present and Potential Future Vehicle Emissions in China on Regional Air Quality:  The benefit of vehicle emission regulations.
Research team:  Eri Saikawa (doctoral student), Denise Mauzerall, Japanese and GFDL collaborators.

Along with industrialization, the number of vehicles in China is growing exponentially.   In this project we evaluate the current and possible future vehicle emissions from China and their impacts on Asian air quality. We modify the Regional Emission Inventory for Asia (REAS) for China’s road transport sector in 2000 and create two scenarios for 2020 using the updated Chinese data for vehicle numbers, annual mileage and emission factors. For the scenarios in 2020, we include a business-as-usual (same emission factors as in 2000), and a Euro 3 scenario. The Euro 3 scenario represents a case in which all vehicles meet the Euro 3 vehicle emission standards in 2020. This is plausible considering that the current national standards for new cars in China are Euro 3. Using the Weather Research Forecast model with chemistry (WRF-Chem), we further examine the regional air quality response to these three scenarios in China in 2000 and 2020. We evaluate the 2000 model results using O3 observations and find a a relatively good fit with a mean bias of 3.3 ppbv for the four simulated months (January, April, July, and October). In 2020, emissions of CO, NOx, NMVOCs, BC and OC are reduced by 78%, 74%, 63%, 63% and 58%, respectively, under the Euro 3 emission standards relative to the business-as-usual scenario. Regional air quality shows great improvement by effective implementation of the Euro 3 emission standards at the national level in China, compared to no regulations. Reduction of more than 10 ppbv O3 and more than 0.5 µg/m³ of BC surface concentrations are found in northeast China. Depending on the season, neighboring countries also see a reduction of up to 5-6 ppbv ozone and 0.05 µg/m³ of BC at the surface. We find that effective regulation of China’s road transport sector will be of significant benefit for air quality within China and more broadly within East Asia (Saikawa, Mauzerall et al., manuscript in preparation).