The Environmental Protection Agency decided to adopt the strictest 8-hour standard for ozone to date, the first changes to occur in this respect in the past decade, the agency announced on Wednesday. Their decision was supported by scientific evidence that points out to the fact that ozone is the primary responsible for smog.

Stephen L. Johnson, EPA Administrator, said this is a step forward to keeping America clean, by complying with the requirements of the Clean Air Act. “America is cleaner today than it was a generation ago,” said Johnson.

The 8-hour standard (the average quantity of ozone over an eight-hour period) dropped from 0.08 parts per million (ppm) to 0.075 ppm. The decision still doesn’t meet the 0.06 – 0.07 ppm scientists urged for, but it could be considered a step ahead, if it gets approval.

In addition to the ozone standards established, Johnson also established four principles that in his opinion should guide the Clean Air Act:

1. Protect public health and improve the overall well-being of citizens;

2. Allow decision-makers to consider benefits, costs, risk tradeoffs and feasibility in making decisions about how to clean the air;

3. Provide greater accountability and effective enforcement to ensure air quality requirements are met;

4. Allow the schedule for addressing NAAQS standards to be driven by the available science and the prioritization of health and environmental concerns.

“The Clean Air Act is not a relic to be displayed in the Smithsonian, but a living document that must be modernized to continue realizing results,” Johnson said. “So while the standards I signed today may be strict, we have a responsibility to overhaul and enhance the Clean Air Act to ensure it translates from paper promises into cleaner air.”

According to EPA estimations, lowering standards will bring $2 - $19 billion in health benefits and at the same time, these benefits will go beyond the prices of implementing the new standards, which are said to go no further than $8.5 billion.