Christian Science Monitor Between 1989 and 2008, clean-air rules in California virtually halved the concentrations of black - carbon soot in the state's skies, in effect reducing the state's carbon footprint by the equivalent of cutting carbon dioxide emissions by 21 million tons ...
KPBS A new study commissioned by the California Air Resources Board finds that the reduction of black carbon , or soot levels since the 1980s is comparable to taking 4 ...
