RECENT ENFORCEMENT actions of the Nuclear Regulatory Commission present an interesting contrast with the activity of the Environmental Protection Agency.

The NRC is working harder to make nuclear power plant operators toe the line on safety and security rules. Last week, the commission proposed the stiffest fine ever--$850,000--for alleged safety violations at a plant in New Jersey. The incidents were the most serious since Three Mile Island in 1979. They involved the failure of the reactor's automatic shut- down system, and its backup, last Feb. 22 and again on Feb. 25. The electric utility failed to notify the NRC of the breakdown promptly, which is troubling enough. But then the utility continued to operate the reactor until the second incident three days later. The NRC staff investigation concluded that lax management, deficiencies in the training of staff, and inattention to some safety procedures have been serious problems at this particular plant. The fine seems justified. Where are the thumbscrews?

Fines of this magnitude certainly won't destroy a public utility, but senior managers will sit up and take notice. This is part of a more aggressive enforcement effort at the NRC that entails more cases, processed more quickly, and larger fines. It is a welcome and much-needed sign, in view of nagging public concerns over nuclear safety.

But also remember that sulfates produced by coal- and oil-fired utility generators--nuclear power's competition--cause an estimated 30,000 early deaths each year, according to a recent study done for the congressional Office of Technology Assessment. And that's without looking at other major air polluters, such as the steel industry.

Aggressive federal enforcement of the Clean Air Act took a nose dive in the first two years of the Reagan administration, and is now starting a modest recovery. The public health risks addressed by EPA, while substantial, are more diffuse than many of those handled by the NRC. And few industries are as unpopular as nuclear utilities. But the new EPA should take a lesson from the new NRC. It should continue and accelerate the rehabilitation of its air enforcement program. Despite increasing expertise on relative health risks, the stringency of enforcement efforts across different agencies seems curiously unrelated to the number of lives immediately at stake.