For some Mainers, Wednesday’s balmy weather offered a sneak peek of the joys of summer. But for tens of thousands of others here – senior citizens and adults and children with respiratory illnesses – the sunshine and warmth made air quality worse and breathing more difficult. And their plight will only get worse if the Trump administration rolls back progress toward cleaner cars.

We’re glad to see Maine pushing back, joining 16 other states in suing the administration Tuesday over its plans to scrap rules designed to make cars more efficient and less polluting. With the Environmental Protection Agency and its administrator, Scott Pruitt, intent on subverting the agency’s mission, Mainers with lung conditions need somebody on their side.

The lawsuit filed this week challenges the rollback of nationwide standards that called for new vehicles to average nearly 55 miles per gallon by 2025. Automakers have pressed the White House for weaker rules – for every state in the country.

But California has long had a waiver to set its own, more-stringent tailpipe emissions standards. Maine and 11 other states have followed suit. Since cars and trucks are the largest source of both greenhouse-gas emissions and high ozone levels, revoking California’s right to tougher rules would stymie efforts to combat climate change and would make many Mainers very sick.

The rules that Pruitt is trying to dismantle would erase hundreds of millions of vehicles’ worth of the pollution that combines with sunlight to create ozone – which spikes in Maine because we’re downwind of coal-fired power plants in the South and Midwest and cars and trucks in the densely populated Northeast Corridor.

Over 24,000 Maine children and 120,000 Maine adults have asthma, the American Lung Association estimates, while 87,000 adults in Maine have chronic obstructive pulmonary disorder. For them, warmer weather doesn’t mean picnics and walks outside – it means air quality alerts, like the one issued this week by Maine environmental officials, and a greater risk of a flare-up, hospitalization or even death.

The 17 states that are suing the administration represent about 43 percent of the new-vehicle market and 44 percent of the U.S. population. Since the Trump administration will surely continue its indefensible push to lift car-efficiency standards, the millions of Americans who want – and deserve – cars that don’t make them sick should be prepared to push back. Especially in Maine, summer is too short to spend inside.