About NRDC

NRDC Experts: Air

Air pollution, both indoors and outdoors, poses health risks to millions of Americans every day, contributing to asthma, emphysema, heart disease, and other potentially lethal conditions. Managing air pollution causes, and defending successful safeguards, such as the Clean Air Act, is critical to the human, economic, and environmental health of our communities. Read more.

John D. Walke

John D. Walke Director, Climate & Clean Air Program


John D. Walke is a senior attorney and clean air director for NRDC in Washington, D.C., a position he has held for more than ten years. He is responsible for NRDC’s national clean air advocacy before Congress, the courts, the U.S. Environmental Protection Agency (EPA) and the public. Prior to joining NRDC in 2000, John worked for the EPA in the air and radiation law office of the Office of General Counsel, from 1997 to 2000. At EPA, John worked on permitting, air toxics, monitoring, and enforcement issues under the Clean Air Act. Before working at the EPA, John was an associate in the Washington, D.C. law firm, Beveridge & Diamond. John graduated from Duke University in 1990 with a B.A. in English and from Harvard Law School in 1993 with a law degree.

Melissa Lin Perrella

Melissa Lin Perrella Director and Senior Attorney, Southern California Air Program

Press Contact:
Dylan Gasperik

Areas of Focus

Air pollution, environmental justice, ports, rail yards, diesel, preemption, national environmental policy act, California Environmental Quality Act.


Melissa Lin Perrella is a Senior Attorney and Director of Western Air Quality and Environmental Justice in NRDC’s Santa Monica office. Melissa specializes in representing communities adversely affected by our nation’s freight transportation system. She is an expert on the health effects of diesel emissions and on solutions for reducing air pollution from port and rail yard operations. Melissa has litigated to enforce the National Environmental Policy Act and California Environmental Quality Act, and has helped develop and defend landmark state and local clean air initiatives against federal preemption claims.

Melissa joined NRDC in 2004 after working in private practice at Orrick, Herrington & Sutcliffe LLP in Los Angeles, CA as a general litigation associate. She received her law degree from Georgetown University Law Center, and bachelor’s degrees in Ethnic Studies and Social Welfare from U.C. Berkeley. Melissa is also a mother and proud finisher of the Boston Marathon.

*Admitted to practice in California
David Pettit

David Pettit Senior Attorney, Urban Program

Press Contact:
Dylan Gasperik

Areas of Focus

Litigation, air pollution, oil spills, California Environmental Quality Act, federal natural resource damages assessment proces, sustainability, alternative energy, green development, environmental health, environmental justice and reform, environmental policy.


David Pettit is director of NRDC's Southern California air program in Santa Monica and an experienced trial and appellate lawyer. Since joining NRDC in 2007, he has focused on curbing pollution in California by litigating against polluting industries and campaigning for clean, alternative energies and greener development in urban areas.

David has litigated environmental cases in state and federal trial and appellate courts for many years in private practice and at NRDC, including major air pollution matters, offshore oil spills, groundwater pollution, habitat preservation, and natural resource damage assessment disputes. He has a B.A. in philosophy and a law degree from UCLA.

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