The existing national air quality standards for carbon monoxide adequately protect public health and the environment, EPA said last week in announcing its decision to retain the 40-year-old rules. Since 1980, levels of CO in the air have fallen by 80%, mostly as a result of motor vehicle emissions controls, the agency said. The current health standards are 9 ppm measured over eight hours and 35 ppm measured over one hour. “CO levels at monitors across the country are quite low and are well within the standards, showing that federal, state, and local efforts to reduce CO pollution have been successful and are providing important public health protections to all Americans,” EPA said in a statement. Activist groups such as the American Lung Association called the agency’s decision a missed opportunity to strengthen the regulations. “This is a disappointing step, and a sad 40th anniversary for these weak national standards, set in 1971,” said ALA President and CEO Charles D. Connor. However, EPA said the standards are “consistent with the advice and recommendations” made by an independent panel of expert scientists who advise the agency, the Clean Air Act Scientific Advisory Committee.