Faced with stiff opposition in Congress and a court-ordered deadline, the Environmental Protection Agency on Wednesday said it will make it much cheaper for companies to reduce toxic air pollution from industrial boilers and incinerators.

In an overhauled regulation obtained by The Associated Press in advance of its release, the EPA said it has found ways to control pollution at more than 200,000 industrial boilers, heaters and incinerators nationwide at a 50 percent cost savings to the companies and institutions that run them. That would save $1.8 billion and still avert thousands of heart attacks and asthma cases a year, the agency said.

These rules "put in place important public health safeguards...at costs substantially lower than we had estimated under our original proposal," Gina McCarthy, EPA's top air pollution official, said in a statement. EPA had put the initial cost at $3.9 billion. An updated jobs analysis completed by the agency shows the changes will create 2,200 jobs, and that doesn't include employment stemming from purchases of pollution-control technology.

The EPA said the cost savings for polluting industries is in line with President Barack Obama's Jan. 18 executive order to review regulations that hurt job growth.

Republicans and some Democrats in Congress have harshly criticized the EPA recently over the costs of a whole host of regulations, including the first-ever rules to control the gases blamed for global warming. At least a half-dozen bills have been introduced this year to block or curtail agency regulations, and House Republicans succeeded last week in attaching numerous anti-EPA measures to a bill aimed at funding the government for the rest of this fiscal year.

In the case of the boiler rule, EPA was under a court-ordered deadline to release a final regulation this week after a federal court in 2007 threw out regulations drafted by the Bush administration. The Obama administration had asked the court for a 15-month extension in order to review the more than 4,800 public comments that came in, but the court gave the agency 30 days. The EPA said Wednesday it would reconsider the rule and take additional public comment, since the regulation included significant changes based on data and information provided by industry.

In a letter sent to administrator Lisa Jackson Friday, six senators expressed concern about whether the EPA had enough time to make improvements to the rule. The four Republicans and two Democrats wrote that the boiler rule could make municipalities, universities, and federal facilities vulnerable to "excessive and expensive regulatory burdens."

Industrial boilers, which burn coal and other fuels to generate steam and hot water for heat and electricity, are used by refineries, chemical plants, hospitals and even churches. They are also the second-largest source of toxic mercury emissions in the United States after coal-fired power plants. Mercury is a metal that even at low levels can cause subtle but serious damage to the brain and senses.

Under the new rule, the bulk of industrial boilers at small facilities would not have to meet certain pollution standards. Instead, they would have to do tune-ups every two years to reduce emissions. The roughly 13,800 large industrial boilers at refineries, chemical plants and other factories would still have to comply with new emissions standards requiring them to install technologies to reduce pollution in three years.

The EPA also reduced compliance costs by exempting clean-burning fuels from meeting the new emissions limits, something that initially applied only to natural gas-fired boilers.