The American Environmental Protection Agency (EPA) has published new guidance to help authorities that are failing to meet new pollution-reducing standards. The move comes as part of a US-wide effort to improve air quality and reduce ground-level ozone, a major contributor to smog that also damages crops and other vegetation. The new rules and guidance give advice on how to develop plans to reduce ozone pollution in areas that do not meet required standards. "This rule signifies EPA's commitment to working with communities to develop cost effective plans," the EPA's acting assistant administrator for air and radiation Bill Wehrum said.