It is no simple task to balance environmental concerns about climate change and health problems from carbon emissions with the equally compelling reality that Americans need electricity to heat, cool and light their homes.

In a major step to clamp down on a key source of man-made greenhouse gases, the Environmental Protection Agency has proposed rules to limit carbon-dioxide emissions from new coal-fired power plants.

Existing coal-fired plants, and those under construction within the next 12 months, would be exempt from the rules because complying with the new edict would pose an undue economic burden and require technology that is mostly experimental. But if a utility wants to build a coal-fired power plant in the future, the facility must meet the EPA’s new emissions level, less than 1,000 pounds of carbon dioxide per megawatt hour of electricity.

This is a sensible compromise between the nation’s immediate energy needs and pressing environmental concerns.

By exempting existing plants and those under construction, the EPA action should allay concerns that tougher rules would lead to power shortages and blackouts. And by setting a deadline and emissions level, the EPA also has drawn a policy bright line that should please environmentalists: Coal must be cleaner in the near future or it won’t be used.

The new rules are in line with an industry-wide shift away from coal and toward cleaner sources of electric power. Utilities have relatively few new coal-fired plants on the drawing board, and natural-gas prices are near 10-year lows. The latest generation of gas-fired power plants is expected to be able to meet the new emissions levels.

Ultimately, existing coal-fired plants must become cleaner or be retired. The benefits would be fewer health problems from bad air, including premature deaths.

Cleaner air must be the endgame, one that will save taxpayers, employers and state and local governments billions of dollars in health-related costs and other economic hardships.