Sheldon K. Friedlander, whose work in identifying the sources of particles in Southern California smog led to new ways of studying and regulating air pollution, has died. Friedlander died Feb. 9 at his home in Pacific Palisades of complications from pulmonary fibrosis, his family said. He was 79. While a professor at the California Institute of Technology in the 1970s, he was among the founders of aerosol science - the study of gases and particles in the air. Friedlander discovered a way to analyze the chemical makeup of smog particles and trace what was creating air pollution at any given...