Instrument to measure pollution is mounted on a tower atop a 25-story building.
PULLMAN, Wash. – Researchers from the Washington State University Laboratory of Atmospheric Research traveled to China last summer to measure air pollution in an emerging megacity and to help that country increase its understanding of air quality impacts.
The project, the first of its kind in China, is part of a three-year, multi-institutional effort to measure emissions of air pollutants and greenhouse gases in Xi’an. With 8 million people, it is one of the country’s oldest and most rapidly growing cities.
The project is supported by the National Science Foundation and was hosted by collaborators at the Institute of Earth Environment, part of the Chinese Academy of Sciences. Researchers from the National Center for Atmospheric Research (NCAR) also are participating in the study.
Intense pollution in megacities
Tim VanReken, right, with his doctoral student
George Mwaniki, left, and Chinese host scientist
Junji Cao.
The laboratory has a long relationship with NCAR and has worked on other, similar multi-institutional efforts to look at impacts of megacities on global and regional environments. Such large cities have intense urban pollution problems, said Tim VanReken, assistant professor in the WSU Department of Civil and Environmental Engineering.
As the world’s most populous country, China will have eight cities with populations of more than 10 million by 2025. The country has significant emissions and few pollution regulations, VanReken said.
Much of the country gets its electricity from coal, which is relatively cheap but can also be highly polluting. Pollution controls are expensive but concern over health impacts is growing, especially in the biggest cities.
Impacts on nearby forests, ag studied
The Xi’an study will help to answer how pollution affects people and how it impacts the surrounding agriculture, forests and biodiversity.
Xi’an is a good city to study because of its proximity to agricultural areas as well as to a nearby mountain range.
“This is a good city to look at the impacts on the natural environment,’’ said VanReken.
Many pollutants measured
As part of the study, researchers installed a 25-meter tower on a 25-story building on the campus of Xi’an Jiaotong University. They measured a variety of pollutants, including carbon monoxide, particulates, nitrogen oxides, volatile organic compounds, carbon dioxide and other greenhouse gases such as methane and nitrous oxide.
Concentrations of pollutants were averaged every five minutes to understand short-term changes. The researchers actually made measurements much more frequently, as much as 10 times per second. This will allow them to look at fluxes and determine how much of the different pollutants are being emitted by urban activities.
Efforts new to China
While urban areas of the U.S. have detailed inventories of emissions that help guide regulations, China generally doesn’t have that kind of information, VanReken said.
“This is the first step toward a very detailed emissions inventory,’’ he said. “By providing good data sets, we can build good quality models that eventually can be used in air quality policy making.’’
VanReken will present the results from this experiment and other recent LAR work on urban emissions at the Planet Under Pressure conference in London in the spring.