In rural locations, a maximum sulfur content of two percent is allowed. Nitrogen oxide emissions from cars also contribute to acid rain. In Maryland, nitrogen oxide controls are also required for new municipal waste incinerators and power plants. MDE operates acid rain monitoring stations in Rocky Gap State Park in Allegany County and at the Elms Environmental Center in St. Mary's County. Both stations were established in 1984 to determine the long-term effects of acid deposition in Maryland.
Studies are underway to measure the environmental effects of acid rain in Maryland.
The studies are conducted jointly by the Maryland Departments of Natural Resources and Environment. The results of this research help us better understand the problems and costs of controlling acid rain. The 1990 federal Clean Air Act Amendments require power plants across the nation to reduce sulfur dioxide and nitrogen oxide emissions. The amendments also impose tougher emissions standards for passenger cars and light duty trucks. These measures will reduce significantly the pollutants that contribute to acid rain formation.