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CHINA RESEARCH: Impacts of air pollution on agriculture and public health with implications for energy and air pollution policy
Research Team: Denise Mauzerall, Xiaoping Wang (doctoral student) and collaborators (see references)
Due to population growth, industrialization and increasing fossil fuel consumption, China is experiencing serious and worsening air pollution and is of strategic importance in determining future background levels of air pollution in the northern hemisphere. China is also presently the second largest emitter of greenhouse gases in the world and, despite recent reductions in carbon dioxide emissions, may become the largest emitter within the next few decades.
Our objective has been, through identification of local damages to agriculture and public health , to inform the development of future energy and environmental policies which reduce emissions of both reactive air pollutants and greenhouse gases, and hence have both local and global benefits. Our work is among the first integrated assessments of air pollution impacts in Asia. Our integrated assessment approach incorporates emission estimates, atmospheric modeling, exposure-response relationships and economics to estimate the value of environmental damages due to air pollution. Although uncertainties exist at each step of such an assessment, the approach allows us to quantitatively link emissions, with concentrations of air pollutants in the atmosphere, with exposures, with impacts, and ultimately with technology/policy options that reduce damages from emissions.
Agricultural Impacts in East Asia
Ozone is well documented as the air pollutant most damaging to agricultural crops and other plants. Most crops are grown in summer when ozone concentrations are frequently sufficiently elevated to reduce yields. While extensive research on the impacts of ozone on agriculture has been conducted in the United States in the 1980s and in Europe in the 1990s, little research has focused on agriculture in Asia [Mauzerall and Wang, 2001].
Our recent work partially fills that gap. We used a sophisticated atmospheric chemistry transport model (MOZART-2) to simulate ozone concentrations in 1990 and 2020 over Asia, and available concentration-response functions to characterize yield reductions due to ozone exposure. Our estimates show that due to ozone concentrations in 1990 China, Japan and South Korea lost 1–9% of their yield of wheat, rice and corn and 23–27% of their yield of soybeans. In 2020 we project grain loss due to increased levels of ozone pollution to be 2–16% for wheat, rice and corn and 28–35% for soybeans [Wang and Mauzerall, 2004].
Although we used the best tools presently available, our estimate has uncertainties associated with the accuracy of our emission inventory for 1990 and projected for 2020, with ozone concentrations simulated by MOZART-2, and with the application of concentration-response relationships for non-Asian crop cultivars to East Asia. Our results still signify, however, that East Asia, a region that produces over 20% of the world’s grain, is potentially on the cusp of major reductions in agricultural yields due to projected increases in surface ozone concentrations.
Public Health Impacts in Eastern China
We found that public health in eastern China is heavily impacted by fine particulate air pollution. We again use an integrated assessment approach to link energy consumption and technologies to air pollution, resulting impacts on premature mortalities and morbidity and finally to the value of the resulting health damages. We make significant advances over previous work by developing a new emission inventory which is highly spatially and temporally resolved 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.
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 Models3 to simulate ambient air pollution concentrations in eastern China and comparing 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 underestimate actual emissions. We then used projected energy demand and associated emissions in 2020 to simulate air pollution levels under business-as-usual (BAU), with best available emission control technology (BACT) and with implementation of advanced coal gasification technologies (ACGT).
Our study focused on Zaozhuang (a city in eastern China heavily reliant on coal) to address two questions: 1) How much health damage does the air pollution from Zaozhuang cause based on the year 2000 and projected year 2020 emissions? 2) To what extent can alternative technologies contribute to averting premature mortality and respiratory morbidity in 2020?
To evaluate the impacts of air pollution on mortality, we used concentration-response functions in the epidemiological literature from long-term cohort studies conducted in the United States. Long-term studies best represent total effects of air pollution and no such studies are available for China. Asia differs from the United States in the nature of its air pollution, the magnitude of exposure to that pollution, and the health status of its populations. However, a recent literature review of studies of short-term exposure to air pollution in Asia found similar increases in daily mortality and morbidity as those found in Western countries, lending support to our approach.
We estimated that total health damages due to year 2000 anthropogenic emissions from Zaozhuang, using the “willingness to pay” metric, were equivalent to approximately 10% of its GDP. With no new air pollution controls implemented between 2000 and 2020 but with projected increases in energy use (BAU), health damages from air pollution exposure may 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, our study provides valuable insight into the implications of increasing air pollution levels in eastern China and different possible policy options. We quantitatively demonstrate that benefits to public health, of substantial monetary value, could be achieved in eastern China through the use of additional pollution controls and particularly from the use of advanced coal gasification technology [Wang and Mauzerall, in press]. We are sharing our research results with Chinese scientists and government officials through international meetings in China and by translating our papers into Chinese.
PUBLICATIONS:
Mauzerall, D. L. and Wang, X., “Protecting Agricultural Crops from the Effects of Tropospheric Ozone Exposure: Reconciling Science and Standard Setting in the United States, Europe and Asia,” Annual Review of Energy and the Environment, 26, pp. 237-268, 2001. [full text (pdf)]
Wang, X. and Mauzerall, D. L., “Characterizing Distributions of Surface Ozone and its Impact on Grain Production in China, Japan and South Korea: 1990 and 2020,” Atmospheric Environment, 38, pp. 4383-4402, 2004. [full text (pdf)]
Wang, X. and Mauzerall D. L., “Evaluating Impacts of Air Pollution in China on Public Health: Implications for Future Air Pollution and Energy Policies,” Atmospheric Environment, in press 2005. [full text (pdf)]
Xiaoping Wang, Denise L. Mauzerall, Yongtao Hu, Armistead G. Russell, Eric D. Larson, Jung-Hun Woo, David G. Streets and Alex Guenther, “A high-resolution emission inventory for eastern China in 2000 and three scenarios for 2020,” Atmospheric Environment, Volume 39, Issue 32, Pages 5917-5933, October 2005. [full text (pdf) supplemental information (pdf)]