Distinguished atmospheric scientist Glen R. Cass died of cancer on Monday July 30 at Duke University in North Carolina. At the age of 54, he had earned widespread regard for both his professional achievements and personal integrity.

“Glen Cass was one of the most prolific publishers in ES&T, and more importantly, one of the most significant research directors in the field of atmospheric sciences in the world,” says William H. Glaze, ES&T's editor. He adds that Cass was an active member of the ES&T Editorial Advisory Board since 1998 and “heroically attended our meeting last May, although it was clear that he was suffering.”

Cass held joint appointments at the California Institute of Technology (Caltech) and the Georgia Institute of Technology (Georgia Tech). After earning his Ph.D. at Caltech in 1978, he served as a professor of environmental engineering and mechanical engineering. In 2000, Cass was hired to chair the Earth and Atmospheric Sciences department at Georgia Tech, where he was also a professor of civil and environmental engineering.

Cass made a name for himself by painstakingly sleuthing out the myriad sources of air pollution that plague Los Angeles, beginning in the 1980s. “An urban environment like L.A. is one of the hardest places to take that on,” says Christine Sloan, director of technical strategic development at General Motors, who collaborated with Cass on the project. Cass and his group ultimately generated a comprehensive database of source-emitted and ambient aerosol particles “that is without peer,” says John Seinfeld, who holds the Louis E. Nohl Professor chair at Caltech's chemical engineering department. Sloan remembers Cass making measurements everywhere possible, even inside fast food restaurants. “He knew the difference between whether [the food was] fried or grilled, and even what kind of oil they used,” she says.

The long series of papers that resulted from this ongoing study “constitutes the definitive body of work on the chemical composition of organic aerosols,” Seinfeld says. “His analytical chemistry was so meticulous that Glen was able to find traces of nicotine and cholesterol in atmospheric particles, markers for cigarette smoking and meat cooking in the ambient atmosphere. This body of work is of inestimable importance to air pollution research.”

In 1999, Cass initiated a global ozone study at 500 sites around the world that continues today. The effort includes seven monitoring stations in China, and four in India and the Maldives.

Cass's dedication to his graduate students was notable, says Janet Hering, a member of the ES&T Editorial Advisory Board and an associate professor at Caltech's Environmental Engineering Science department. “He was beloved by his grad students,” attests Lynn Hildemann, an ES&T associate editor who studied under him at Caltech before moving on to Stanford University, where she now serves as associate chair of the Civil and Environmental Engineering Department. “He took us into his family when we came to Caltech,” adds Susan Larson, now an associate professor of Civil Engineering at the University of Illinois-Champaign Urbana. “His research was always geared toward improving society,” she adds, noting that she felt that he did an outstanding job of transmitting this approach to practicing environmental science to his students.

Cass served on the U.S. EPA's advisory committee on Ozone, Particulate Matter and Regional Haze Implementation Programs and on the agency's Clean Air Scientific Advisory Committee. He was also a member of the Health Effects Institute's research advisory committee, and was named to advisory panels for the National Research Council and the South Coast Air Quality Management District. In addition to serving as an author on more than 145 scientific publications, he contributed chapters to a dozen books and dozens of technical reports. For reprints of Cass's publications, contact Caltech.

“For his many good works and his service to the profession, we will always be indebted to him,” Glaze says. The Caltech flag is being flown at half-mast in honor of his passing. —KELLYN S. BETTS