The U.S. Environmental Protection Agency’s proposed new standard for ground-level ozone, if enacted, would be the most stringent ever proposed. The measure would cost industry billions of dollars to reach compliance, by the agency’s own estimates.

The proposal, signed on Jan. 6, would set the “primary” standard, which protects public health, at a level of between 0.060 parts per million and 0.070 ppm measured over eight hours. EPA also proposes a “secondary” standard to protect plants and trees. EPA estimates it will cost between $19 billion and $90 billion to implement the proposal.

In 2008, the Bush administration revised the standards for the first time in a decade to 0.075 ppm. But EPA was widely criticized at that time by environmental groups, which argued that the standard did not go far enough, and industry groups, which opposed a new standard altogether.

EPA says it opted for a more stringent standard after reviewing more than 1,700 scientific studies and public commemts. The agency contends that the stricter standard would save thousands of lives. Industry groups counter that the change could push more counties across the nation out of attainment and consequently jeopardize funds for federally supported transportation projects.

Potential restrictions on construction equipment use are another concern for construction groups. Leah Pilconis, Associated General Contractors’ senior environmental adviser, says, “As EPA continues to tighten the air-quality standards, states are challenged to find ways to reduce emissions….We’re seeing restrictions on the operations of construction equipment popping up” in contract documents across the nation.