the California Air Resources Board ( carb ) has approved over us $600,000 for two research projects aimed at studying the effects of air pollution on children's health. The projects are important as they will evaluate the impacts of both compressed natural gas buses ( cng ) and diesel buses that are fitted with soot traps. The results of the projects are expected in 2003 and will be used as guidelines for formulating more effective air quality rules with regard to children's health. They will also serve as a basis for evaluating the benefits of alternative fuels and emission-control technologies. The projects are a follow up of a study, which found that exposure to some pollutants and toxic compounds is 10 times higher inside vehicles than in ambient air (see Down To Earth , Vol 10, No 1, May 31, 2001, p14).