EPA is reconsidering a 2009 rule that set air pollution standards for various categories of chemical manufacturing operations. The action comes in response to a petition filed by the American Chemistry Council and the Society of Chemical Manufacturers & Affiliates, two industry trade associations. The final rule established national standards to reduce emissions from equipment vents of 15 hazardous air pollutants, including acetaldehyde, hydrazine, and chloroform. It applies to nine categories of chemical manufacturing: agricultural chemicals and pesticides, cyclic crude and intermediates, industrial inorganic chemicals, industrial organic chemicals, inorganic pigments, miscellaneous organic chemicals, plastic materials and resins, pharmaceuticals, and synthetic rubber. EPA estimates that the regulation covers 450 chemical plants and reduces emissions of air toxics by 248 tons per year. Compliance costs industry a total of about $3.2 million annually, according to the agency. Requirements for covers or lids on process vessels and certain inspections of leaks are among the issues EPA is reconsidering.