One of Japan's largest pollution suits ended Thursday when about 400 Kawasaki residents signed an agreement to drop all claims, including for compensation, in exchange for a vow from the state and the Metropolitan Expressway Public Corp. to "seriously work" on improving air quality along highways.

The plaintiffs said they agreed to accept the Tokyo High Court-mediated settlement of their 17-year legal battle because it clearly states that air pollution is "an ongoing problem" in Kawasaki and that such pollution has been caused not only by factory emissions in the industrial city but also by car exhaust.

The plaintiffs claimed their illnesses, including asthma and other respiratory disorders, were caused by auto emissions as well as by industries.