Our National Park system—the first in the world—has been dubbed “America’s best idea.” But that great idea, which offers millions a respite from our industrialized life, is now beseiged more than ever by a symptom of that life—smog.

The National Parks Conservation Association published a report last week showing that the number of bad ozone (smog) days in national parks has risen over the last three years. Flagship parks like Great Smoky Mountains, Rocky Mountain National Park, Grand Canyon, and Big Bend all had ozone violations over the last six months. Sequioa/Kings Canyon National Park suffered the worst—choking on smog for more than two months.

Smog is bad for the Parks—obscuring famous and magnificent views and depositing pollutants that foul lakes and streams.

But it’s not so good for the visitors either, since its tied to all sorts of lung and heart disease. High enough ozone levels trigger recommendations for people to stay indoors and limit outdoor exercise, which kind of ruins the whole national park experience.

Of course, many cities—and, increasingly, rural areas in the West that are surrounded by oil and gas drilling such as remote Pinedale, Wyoming—suffer from high ozone levels too, not just national parks. Which makes President Obama’s cave-in to polluters earlier this month by putting off tighter health-based protections for ozone more depressing.

But even Obama’s surrender on tougher ozone standards is not enough for some members of the House of Representatives, who have sponsored legislation to force EPA to delay implementation of life-saving limits on air pollution, including smog. The “TRAIN” Act would lock in outdated standards that lead to unnecessary asthma attacks, heart attacks, and more than 100,000 premature deaths.

If the National Park System is America’s best idea, promoting death by smog has to rank near the bottom.