Connecticut and eight other states have sent a letter to the U.S. Environmental Protection Agency urging immediate action to require nine upwind states to address air pollution generated within their borders that causes air quality and public health issues in downwind states, the state Department of Energy and Environmental Protection announced Thursday.

In a letter to EPA Administrator Gina McCarthy, environmental commissions of nine Northeast and Mid-Atlantic states asked EPA to act on a petition they had filed on December 10, 2013, seeking to add nine upwind states — Illinois, Indiana, Kentucky, Michigan, North Carolina, Ohio, Tennessee, Virginia, and West Virginia — to the Ozone Transport Region, DEEP said in a news release.

Granting the petition, and adding the nine upwind states to the OTR, would require them to install and operate the same air pollution controls that are required from similar sources in the Northeast and Mid-Atlantic states and improve air quality in both upwind and downwind states, DEEP said.

Under Section 176A of the federal Clean Air Act, states can petition the EPA to add any state to an air quality region such as the OTR if there is reason to believe it is the source of pollution-causing violations of air quality standards elsewhere. The EPA administrator was required to approve or disapprove the petition by June 10 but action was postponed as the states entered into a collaboration to craft a resolution to eliminate the need for the petition, DEEP said.

While the collaboration was able to obtain voluntary emissions reductions from power plants in some upwind states during the 2015 ozone season, it was but unable to achieve legally enforceable control measures to address ozone transport for 2016 and beyond, DEEP said. As a result, the petitioning states have asked EPA to take formal action on and to grant the petition.

“Connecticut continues to measures the highest ozone levels in the northeast affecting the health of our citizens,” said DEEP Commissioner Rob Klee. “Over 90 percent of our air pollution comes from out of state on ‘bad air’ days. Over the past year, DEEP has worked with the upwind states with the goal of achieving a satisfactory resolution to reduce interstate air pollution transport, but we have come to an impasse. The continued lack of meaningful and binding emissions reductions puts the health and welfare of our citizens at continued risk. It’s now time for EPA to act.”

Klee said that over the last few decades, Connecticut and other states in the Northeast and Mid-Atlantic regions have spent tens of billions of dollars to reduce air emissions.

“It is now time for the upwind states to make similar investments so that their power plants and industrial facilities operate in a clean and efficient manner and stop spewing pollution that is carried over our borders and into the lungs of Connecticut’s residents,” he said.

The states that filed the petition are Connecticut, Delaware, Maryland, Massachusetts, New Hampshire, New York, Pennsylvania, Rhode Island and Vermont.