The U.S. Supreme Court on Thursday halted, at least temporarily, a Biden administration rule that would have helped moderate Connecticut’s longstanding summertime smog and other air quality problems.

The rule would dramatically cut Midwestern and Western power plant and industrial emissions that travel east into Connecticut and contribute to the state’s high asthma rates and air quality that is perpetually out of compliance with federal standards.

The court’s action, a 5-4 decision written by Neil Gorsuch with the three liberal justices and Amy Coney Barrett dissenting, once again thwarts decades of legal efforts by Connecticut to force upwind states to do something about the cross-state pollution that disproportionately plagues Connecticut.

“This case is going to have a direct impact on the air quality of Connecticut and the entire Long Island Sound region, the entire New England region,” said Roger Reynolds, senior legal director for the environmental advocacy group Save the Sound. “Connecticut and New York are working hard to reduce emissions, but that’s being completely undermined by pollution that’s coming in through these Midwest power plants. And if we’re not able to address the pollution from the Midwest power plants, we’re never going to be able to effectively address pollution in Connecticut.”

“This disappointing decision is a serious setback for Connecticut’s air quality and public health,” said Attorney General William Tong in a statement. “As Justice Barrett states in her dissent, this injunction ‘leaves large swaths of upwind states free to keep contributing significantly to their downwind neighbors’ ozone problems for the next several years.’ That’s an unacceptable outcome. But our fight is not over. While the Supreme Court has temporarily paused enforcement of the Good Neighbor Provision, we will continue to aggressively pursue our ongoing litigation.”

The ruling adds to the list of recent pushbacks to Biden administration environmental policies by this most conservative iteration of the Roberts court. Two years ago, it prevented the Biden administration from regulating greenhouse gas emissions from existing power plants. It narrowed what bodies of water can be protected under the Clean Water Act. Before this term ends, there will a major decision that many expect will significantly weaken the power of administrative agencies like the Environmental Protection Agency to follow the science. On Tuesday, the court announced that next term it would take up a challenge to the 1970 National Environmental Policy Act that requires in-depth environmental reviews for federal projects.

“This is the worst three years for the environment in the Supreme Court ever, since the passage of our major environmental laws in the early ’70s,” Reynolds said. “There is a clear pattern of weakening the ability of agencies, and there’s a particular focus on the EPA.”

The rule at issue, known as the Good Neighbor Plan, was finalized by the Biden administration in March 2023. It ordered 23 states in the Midwest and West to reduce pollution from their power plants and industrial operations, tightening previous standards set in the Obama administration. The Trump administration took no similar action, even though to be in compliance with the Clean Air Act, it was supposed to. The Clean Air Act, in place since 1970, contains a good neighbor policy designed to keep upwind states from polluting downwind ones.

While the rule was implemented in some of the states, many states had fought the plan, resulting in a hodge-podge of court rulings that have and have not included stays of the rule. A few states that were not granted stays appealed to the Supreme Court as an emergency, and the court decided to hear the appeal to decide whether to grant the stay while the various cases continue to wind through courts.

Connecticut was among a dozen states and other entities that filed comments with the Supreme Court asking it to not impose a stay.

In the meantime, Connecticut is facing yet another summer of air pollution and bad air quality. Pollution emanating from the west and south of Connecticut typically travels east and north on the prevailing winds and in the summer essentially “cooks” in the sun, forming ozone or smog. Connecticut is its landing pad.

The EPA has noted that “southern Conn. experiences the highest ground-level ozone levels in the eastern half of the U.S. The ozone recorded at air quality monitors in Southwest Conn. comes almost entirely (90-95%) from out of state. Connecticut cannot reach attainment with EPA’s ozone air-quality standard without upwind emission reductions from sources in States south and west of Connecticut.”

The American Lung Association’s 25th annual State of the Air Report, released late last year, found that, once again, Connecticut received an F grade in four of its eight counties for high ozone levels, and that Fairfield County has the worst ozone pollution east of Texas.

For nearly half-a-century most of Connecticut has registered ozone that exceeds the National Ambient Air Quality Standards set by the EPA. Right now, the southern part of the state — Fairfield, New Haven and Middlesex counties — doesn’t even meet the more lenient 2008 standards. Officially, that’s called being “in non-attainment,” and those counties worsened in recent years to being in “severe non-attainment.” The entire state is in moderate non-attainment with the stricter 2015 standards. It’s anticipated that designation will worsen to “serious.”

Already this ozone season, which runs from March through September, the state has registered 12 bad air days. In the whole of last season there were 19, low for the state and nothing like the brown cloud pollution of the 1970s.

Some of what causes the state’s ozone problem is created locally, largely from transportation. The last coal-fired power plant in New England — the Merrimack Station near Concord, N.H. — is set to close in 2028.

The Good Neighbor Plan as conceived would have taken effect in 2026. EPA projects that in that year alone it would have prevented some 1,300 premature deaths, avoided more than 2,300 hospital and emergency room visits, cut asthma symptoms by 1.3 million cases, avoided 430,000 school absence days and 25,000 lost workdays.

The high court is likely to see the case again as the lower court challenges continue to play out.

This story was originally published by the Connecticut Mirror.