<P> Further amendments were made in 1990 to address the problems of acid rain, ozone depletion, and toxic air pollution, and to establish a national permit program for stationary sources, and increased enforcement authority . The amendments also established new auto gasoline reformulation requirements, set Reid vapor pressure (RVP) standards to control evaporative emissions from gasoline, and mandated new gasoline formulations sold from May to September in many states . </P> <P> Reviewing his tenure as EPA Administrator under President George H.W. Bush, William K. Reilly characterized passage of the 1990 Clean Air Act as his most notable accomplishment . </P> <P> The Clean Air Act was the first major environmental law in the United States to include a provision for citizen suits . Numerous state and local governments have enacted similar legislation, either implementing federal programs or filling in locally important gaps in federal programs . </P> <P> This section of the act declares that protecting and enhancing the nation's air quality promotes public health . The law encourages prevention of regional air pollution and control programs . It also provides technical and financial assistance for air pollution prevention at both state and local governments . Additional subchapters cover of cooperation, research, investigation, training and other activities . Grants for air pollution planning and control programs, and interstate air quality agencies and program cost limitations are also included in this section of the act . </P>

What did the clean air act allow citizens to do that no previous u.s. environmental law had allowed