A federal judge ruled Monday that the Environmental Protection Agency must announce the areas of the country that are breaking caps on smog-forming ozone by the end of next month.

Judge Haywood Stirling Gilliam Jr. of the U.S. District Court for the Northern District of California on Monday ruled that EPA Administrator Scott Pruitt broke the Clean Air Act by missing an Oct. 1, 2017, deadline and ordered the EPA to identify all areas of the nation with unsafe smog by April 30, except for San Antonio. The Texas city was given more time, as state officials are submitting more information to the EPA.

Gilliam was named to the court by former President Barack Obama.

Environmentalists sued the EPA in December for missing the deadline to implement strict standards for controlling smog-forming ozone, set in motion by the Obama administration. The EPA was required under the Clean Air Act to designate noncompliant areas of the country under the 2015 ozone rule by Oct. 1, 2017, but it failed to do so.

Attorneys general from 14 states and the District of Columbia also sued the EPA for missing the deadline.

In November, Pruitt said he was still consulting with states and local regions on how to meet the standards and needed more time before making any decisions.

Under the ozone rules, the EPA must designate regions of the country that cannot comply with the standards and then work with those states to develop plans to reduce the smog-forming pollution, which can cause respiratory problems.

In June, Pruitt tried to impose a lengthy delay on the implementation of the rules, which he reversed after legal challenges.

Pruitt in November announced that 2,646 counties in the country — about 85 percent — meet the new standards, but did not declare the remaining counties as nonattainment areas.

The EPA Monday afternoon said it reviewing the smog information from the states.

“We look forward to working with co-regulators to continue the designations process for the 2015 standards for ground-level ozone. We are evaluating the information provided by governors in February 2018 as part of that process," said EPA spokeswoman Liz Bowman.