The Environmental Protection Agency has approved final rules governing air emissions from industrial boilers and incinerators that burn solid waste and sewage sludge. Gina McCarthy, EPA assistant administrator for air and radiation, says the rules, signed on Feb. 21, were revised significantly from the original proposal because of industry concerns. “These are achievable and realistic,” she says. The rules take effect between 2014 and 2016.

One change was to forgo numeric emission limits on some smaller facilities and instead use work-practice standards when possible. But emissions from larger coal- or biomass-fired units still must comply with numeric limits. The National Association of Manufacturers still says the new boiler rule is “harsh and inflexible.”