The Cardinal Power Station, a coal fired energy plant in Brilliant, Ohio. (Michael S. Williamson/The Washington Post)

Richard L. Revesz and Jack Lienke are co-authors of “Struggling for Air: Power Plants and the ‘War on Coal.’ ”

For many in the Northeast, May is a hopeful time, promising longer, warmer, brighter days ahead. But for public-health advocates, the month marks a darker turning point: the start of ozone season.

Ground-level ozone, the primary ingredient in urban smog, contributes to a variety of respiratory woes, including premature death. Ozone is of greatest concern in the summer months, because hot, sunny days are especially conducive to its formation.

Residents of the D.C. and Baltimore areas are no strangers to summer smog. But this year, they might be able to breathe easier. Under Gov. Larry Hogan (R), Maryland has petitioned the Environmental Protection Agency for help bringing ozone pollution in the state to a safe level. Granting this request should be a no-brainer for EPA Administrator Scott Pruitt, who has spent recent weeks touting a Back-to-Basics agenda for his agency that prioritizes “helping states achieve high air quality targets.”

Since the 1970s, the EPA has set nationwide limits on the permissible concentration of ozone in the air we breathe, but many states, including Maryland, do not consistently achieve the agency’s standards. Several Maryland counties have yet to satisfy ozone standards established by the George W. Bush administration in 2008, much less the more stringent limits issued by the Obama administration in 2015.

The problem isn’t that Maryland has failed to reduce ozone-forming emissions within its borders. The problem is that a great deal of Maryland’s ozone pollution — as much as 70 percent on some days — originates in other states. That’s why, last November, Maryland’s Department of the Environment formally petitioned the EPA to force 36 coal-fired power plant units in five upwind states — Indiana, Kentucky, Ohio, Pennsylvania and West Virginia — to reduce their emissions of ozone-forming nitrogen oxides.

Maryland is legally entitled to this relief. The Clean Air Act explicitly requires states to ensure that no pollution sources in their jurisdiction “contribute significantly” to another state’s inability to meet federal air-quality standards. When states don’t live up to this responsibility, the EPA must step in and control the offending sources itself. In 2011, the EPA made a major effort to reduce interstate ozone pollution when it issued the Cross-State Air Pollution Rule, which the Supreme Court upheld. But as Maryland makes clear, additional cuts are needed to protect the public.

Furthermore, Maryland’s demands are far from burdensome. It doesn’t expect the power plants named in its petition to install expensive new pollution-control technology. The plants have the necessary equipment. Maryland just wants them to use it more often. Specifically, it wants the plants to operate emissions controls every day from May through September. Maryland knows that running controls this frequently is feasible; its own plants have been required to do so since 2015.

In Washington, environmental debates tend to split along party lines, with Democrats supporting stronger protections and Republicans opposing them. But Hogan is hardly the first state official to put public health ahead of partisanship when it comes to interstate pollution. In one memorable example, Kentucky’s Jefferson County petitioned the EPA in 1979 to control emissions from a coal-fired power plant in neighboring Indiana. Jefferson County’s judge-executive at the time was Mitch McConnell, now the Senate majority leader.

Pruitt has characterized many of the EPA’s past efforts to reduce air pollution as impermissible intrusions on state sovereignty. Indeed, when he was Oklahoma’s attorney general, he sued to block at least 11 separate EPA regulations from taking effect. But even Pruitt has conceded that, when a pollution problem crosses state lines, federal intervention is sometimes the only viable solution. In this case, coal plants in Indiana, Kentucky, Ohio, Pennsylvania and West Virginia are hurting the people of Maryland, and Maryland’s elected officials do not have the power to stop them. Scott Pruitt does. He should use it.