Most of the world’s forests and lakes are not being destroyed or seriously harmed by acid deposition. Rather, this regional problem is harming forests and lakes that lie downwind from large car-dominated cities and from coal-burning facilities without adequate pollution controls (Concept 18-3). Also, acid deposition has not reduced overall tree growth in the vast majority of forests in the United States and Canada, partly because of significant reductions in SO2 and NOx emissions from coal-fired power and industrial plants under 1990 amendments to the U.S. Clean Air Act.