Legislators had passed weak air-quality laws before, but the protests 41 years ago energized an estimated 10 percent of the nation's population and closed Congress for a day.
Within months, Congress passed the Clean Air Act, creating our first national air-quality standards and giving broad authority to the newly established Environmental Protection Agency, which was directed to regulate lead, carbon monoxide and other dangerous pollutants.
Benefits quickly followed, including a sharp drop in blood-lead levels. The law's psychological effect was also important: Americans began overcoming the myth that environmental protections would cripple industry. Over time, another important feature became the law's capacity to address new pollution threats through amendments and revised rules, something now proving critical for climate policy.
The first amendments came in 1977. Congress required cleaner technology for older facilities seeking upgrades and established special air protections for parks and wilderness areas. Later, in 1990, new amendments tightened sulfur restrictions to address acid rain, caused by burning coal, and initiated a phase-out of chemicals that destroy the Earth's ozone.
The adaptive approach has worked. The EPA reports ambient lead levels have dropped nearly 100 percent, while the particulates that cause respiratory ailments have declined 75 percent. Acid rain has diminished. Refrigerants and other household chemicals no longer eat the ozone. The Centers for Disease Control says the law has saved tens of thousands of lives and billions of dollars in health care costs.
Yet, despite these victories, coal and other industries have never stopped fighting the Clean Air Act. They opposed action on lead, mercury, acid rain, ozone and more, claiming industry would collapse and jobs would vanish.
So it's no surprise that industry's latest attacks are focused on the EPA's use of the Clean Air Act to address greenhouse gases such as carbon dioxide. The agency's action stems from a 2003 lawsuit by Washington, Oregon, California, New Mexico and eight other states, along with several cities and a host of conservation groups, all challenging the Bush administration's refusal to regulate greenhouse gases under the Clean Air Act.
In 2007, the Supreme Court agreed, saying the gases "fit well" within Clean Air Act pollutant criteria and ordering the EPA to reconsider. The agency did so, reviewing reams of research, and in 2009 concluded that the build-up of greenhouse gases threatens the health and safety of present and future generations.
But to hear some tell it, socialism guided the EPA's decision. House and Senate Republicans crafted legislation to strip the agency of its Clean Air Act authority over greenhouse gases pushing their campaign so stubbornly that they nearly shut down the federal government. Additionally, newly empowered House Republicans have made good on promises to stall EPA action through lengthy hearings, investigations and deep budget cuts. Potential presidential candidate Newt Gingrich even proposed eliminating the agency entirely.
A common claim by these clean-air foes is that greenhouse gas regulation is the job of Congress, not EPA "bureaucrats in Washington." They hope we'll forget that Republicans and coal-state Democrats recently killed any possible congressional action on greenhouse gases, leaving the Clean Air Act our only lifeline on climate.
All this should concern Westerners, who increasingly live with thinning snowpacks, dying forests and other climate-related threats to our public lands. Just last month, in the type of story that's sadly becoming common, researchers at the University of Wyoming and Wyoming Game and Fish reported that longer, drier summers are diminishing forage and helping to shrink elk herds in Yellowstone National Park.
We live in an unfolding climate crisis and the Clean Air Act is one of the few tools we have to help us act wisely. This Earth Day is a good time to remember that.
Tim Lydon is a contributor to Writers on the Range, a service of High Country News (hcn.org). He is a wilderness ranger in Alaska.