Possibly bowing to congressional pressure, the U.S. Environmental Protection Agency said on Aug. 23 that it will delay until October its implementation of tougher ground-level ozone rules for powerplants. “We are continuing to carefully consider the proposed options” and public comment received since the rules were proposed in January, EPA said in a statement. The rules had been set to take effect on September 1. But several U.S. senators, citing economic hardships, opposed the new emissions standards in an Aug. 6 letter to EPA Administrator Lisa Jackson. The new rules would further tighten limits on sulfur dioxide and nitrogen oxide emissions, targeting powerplants in 31 states and the District of Columbia.