Acid rain falls on 30 percent of China, according to an official government report on the nation’s environment released yesterday. The nation’s main air pollutant is coal dust laced with sulfur dioxide. The report also found that 10 percent of Chinese companies fail to follow environmental regulations. Some progress has been made in cleaning up major rivers since 1997, and there has been a drop in sulfur dioxide, smoke, and dust in the air during the same period, but the gist of the report is that overwhelming environmental problems still haunt the country.