The Obama administration recently trimmed the amount of ozone allowed in the air, issuing a regulation to fight smog that will prevent hundreds of thousands of asthma attacks but cost businesses and utilities billions of dollars.

The U.S. Environmental Protection Agency (EPA) set a new standard of 70 parts per billion (ppb) for the amount of ground-level ozone allowed, from the current level of 75 ppb set under former President George W. Bush in 2008.

Ground-level ozone is a main component of smog. The cut will prevent 320,000 childhood asthma attacks a year, the EPA says.

But the new limit, envisioned under the Clean Air Act, is the least restrictive that the agency had been considering, and health experts complained it does not go far enough.

EPA head Gina McCarthy said she had tried to be guided by science in an effort to protect Americans’ health. “I did the best with what I have,” she told reporters.

It was President Barack Obama’s second major initiative in less than two months to protect the environment, after the White House announced a sweeping plan in August to reduce carbon emissions from power plants.

Industry will face costs of $3.9 billion under These new rules, the agency has estimated.

Business groups say stringent ozone rules will harm the economy by forcing manufacturers and utilities to buy expensive new “scrubbers” and other technology to make sure their plants reduce emissions of toxins.

States will have years to work with power plants, factories and refineries to limit pollutants like nitrogen oxide and volatile organic compounds, components of smog.

The American Chemistry Council, a Washington-based lobbying group, predicted that the rule will increase business uncertainty. These actions put $10 billion in chemical industry investment at risk,” it said in a statement. We are very concerned that some projects, including new facilities, plant expansions and factory restarts, will remain in limbo until EPA explains how to obtain a permit under the new standards.”

The EPA says the new standards will cut lung ailments and other respiratory illnesses, as well as cardiovascular problems.

For more information or assistance with your Environmental and Health & Safety regulatory compliance needs, contact Ralph Carito at Total Environmental & Safety, LLC (Total) at rcarito@TotalEnviron.com or 908-442-8599.