The next step for Russell was modeling the impact of alternative fuels. The California Air Resources Board (CARB) commissioned him to run an experiment: What would happen if all Los Angeles motor vehicles switched from gasoline to a "clean fuel" -- in particular, methanol? Hundreds of supercomputing hours later, Russell found that the change would significantly cut particulate emissions and formaldehyde, a known carcinogen, as well as ozone, the primary constituent of smog. "The alternative fuels," says Russell, "are smaller hydrocarbons, so they burn cleaner without forming aerosols." This research helped swing policy toward including fuel conversion as a recommended strategy in the 1990 revisions to the Federal Clean Air Act.