When Congress passed the Clean Air Act in 1970, it exempted the oldest dirtiest utilities from the new law’s principal environmental and public health standards. Because these dinosaurs faced certain extinction, the industry argued, it would be a waste of scarce resources to require they be retrofitted in the last days of their lives.

Congress agreed-but misjudged the staying power of these power plants. Today, more than 400 of the old, heavily polluting utilities remain in operation.

Not only are the plants still going, they are growing. From 1992 to 1998, electric generation from these sources increased by more than 15 percent-producing as much smog-forming pollution as emitted by 37 million cars a year. It’s time to close the loophole and require all utilities to operate efficiently and cleanly.

The legislative challenge has proven exceedingly difficult. The Congress has significantly amended the Clean Air Act twice since 1970, and each time the exemption was retained. The owners of these power plants have a substantial financial incentive to protect their loophole. Since the plants are old, and mostly paid for, the maintenance to keep an antiquated plant in operation almost always costs less than building a new efficient plant. And since the owners have resisted paying to clean them up, such plants earn significant profits.

Measuring pollution But while energy companies may calculate profits, we’re left calculating pollution. Emissions from these mostly coal-fired plants cause high levels of ozone, which increase the incidence of respiratory disease and premature aging of the lungs. Acid deposition from sulfur can severely degrade lakes and forests. Mercury, which is highly poisonous, accumulates in fish. Carbon dioxide pollution increases the potential for destructive and irreversible climate change.

Some in Congress and the owners of these plants may be willing to overlook environmental and public health costs because much of the pollution is carried hundreds of miles before it causes harm. Most of these dangerous plants can be found in the Midwest; Michigan’s power plants alone emit as much ozone-forming pollution as all of the power plants in New England, New York, and New Jersey combined.

But weather patterns carry pollution from coal burned in Ohio and Michigan hundreds of miles into New England’s air, forests, lakes, streams, and to our lungs. Although Massachusetts is clearly far ahead of many other states in its efforts to produce clean power, our state has work before us as well. While the five dirtiest power plants in Massachusetts-located in Sandwich, Somerset, Salem, Charlestown and Holyoke-have taken some steps to clean up, and still release more than 90 percent of pollution from utilities in the state.

If each of these plants met modern standards, it would cut pollution equal to more than 750,000 cars each year. Nowadays, we would never let any community be subject to housing a new power plant that pollutes as much as these relics.

Loopholes in the law Nevertheless, because of the loopholes in the Clean Air Act, some of our neighbors live in the shadows of these dangerous smokestacks. For these communities, we have an obligation to clean up our remaining plants.

We have an opportunity to fix this problem. There is a strong consensus in Congress, and throughout the nation, that it is time to restructure our electric utility industry. The driving force behind this consensus is the potential to save working families and businesses billions of dollars in their electricity bills, as competition replaces regulated markets and drives down costs. Many states, including Massachusetts, have moved ahead of federal government and enacted legislation of their own.

As we act to capture such savings, we will have a rare opportunity to enhance environmental and public health protections. I have joined nine other Senators from the Northeast in introducing the Clean Energy Act of 1999. The bill sets forth environmental and public health standards, the legislation closes the 30-year-old loophole for the old plants.

Fighting special interests This will be a very difficult fight. The owners of these old plants staunchly defend their special exemption. But with the introduction of the Clean Energy of 1999, we are making progress.

It is the first time that so many senators from both parties have endorsed a comprehensive approach to clean energy. Now it is critical that Congress supports the citizens who are fighting against special interests-making it perfectly clear that dirty power plants should not be protected by either political party. We know that these polluting power plants must clean up their acts, or retire, as promised.

It’s time to write that common sense principle into our environmental laws.