California Air Resources Board

"Air Pollution in Developing Mega-Cities - Something Old, Something New - Lessons from Los Angeles"

David D. Parrish, Ph.D., Colorado Institute for Research in Environmental Sciences

August 7, 2014

• Presentation
• Interview

Over half of humanity lives in cities. The number of megacities (with populations over 10 million) grew from 3 in 1975 to 19 in 2007, and is projected to increase to 27 in 2025. These megacities are the engines of growing economies, but are also very large sources of air pollutants and climate-forcing agents.

For nearly six decades major urban areas in the earlier developing countries (e.g., Los Angeles) have striven to provide acceptable air quality for their inhabitants. Increasingly stringent emission control efforts have been implemented, and have been remarkably effective in reducing ambient pollutant concentrations. Importantly, this progress has been slow, and significant problems do continue. Substantial and growing air pollution issues are also confronting today's rapidly developing mega-cities, both in Asia and in Africa. Lessons learned and the scientific and engineering knowledge accumulated as earlier developing megacities dealt with air quality problems is a crucial resource for developing megacities, both in responding to current problems and in avoiding some of the more severe problems experienced during earlier urban development. New urban areas also have their own unique character, which will require fresh examination of old approaches to air pollution control.

This talk will examine how several important air pollutants in Los Angeles have responded to control measures over the decades, and show how present pollution in Beijing compares with earlier decades in Los Angeles. A qualitative discussion of the relationship of pollutant concentrations to urban population provides some interesting insights into urban air pollution. Finally, it will be argued that the much larger population density of eastern Asia compared to the western United States is likely to greatly increase the difficulty of improving the air quality in Beijing compared to the Los Angeles experience.

Speaker Biography

David D. Parrish, Ph.D., recently retired from the National Oceanic and Atmospheric Administration (NOAA) where he was a Research Chemist and Program Leader of the Tropospheric Chemistry Group of the Chemical Sciences Division of the Earth System Research Laboratory. His work covered a wide range of topics in atmospheric composition from air quality to climate change. He has been particularly active in the development and deployment of instrumentation capable of measuring a very wide range of chemically important trace atmospheric species, and has coordinated seven of NOAA’s surface and aircraft-based field studies. Dr. Parrish has published more than 200 peer-reviewed papers and is listed as one of the world’s “highly cited” authors in geosciences. Earlier this year, Dr. Parrish completed a report for the Air Resources Board entitled “Synthesis of Policy-Relevant Findings from the CalNex 2010 Field Study”, where CalNex stands for California Research at the Nexus of Air Quality and Climate Change.

More Information

The Chair of the California Air Resources Board invites guests to speak on environmental subjects involving air pollution and global warming. Find additional lectures on the Chair's Lecture Series webpage.