Sunset in Shanghai. In terms of air pollution, China's in its infancy.
Sunset in Shanghai. In terms of air pollution, China's in its infancy.

The environmental laws passed in the 1970s have gone a long way toward cleaning up excesses spawned by the post-World War II economic boom.

We're a bit stumped over how best to finish the job vis-a-vis the nation's water, but not air pollution. Ozone levels fell 33% from 1980 to 2013, thanks to EPA's multipronged attack. Engine and equipment manufacturers are releasing products that meet Tier 4 vehicle-emissions requirements, and the agency's cracking down on coal-fired power plants and dust.

In 1997, EPA allowed ozone levels of 84 parts per billion (ppb). In 2008, that was lowered to 75 ppb. Now, to protect our most vulnerable citizens – children and the elderly – the agency's proposing 65 ppb to 70 ppb and is taking comment about going even further, to 60 ppb.

The agency says the "vast majority" of counties would meet the tougher standards by 2025 with the rules and programs they already have in place or are planning. But if you look at these maps, you'll see that 358 counties will have to take extra action to meet the 70 ppb goal. Another 200 would have to do the same to meet the 65 ppb goal.

Grant total: 558.

The agency's also proposing changing the “secondary” standard to between 65 ppb and 70 ppb to protect plants and trees, which studies show are stunted by ozone exposure.

The agency plans to hold three public hearings before issuing final ozone standards by Oct. 1, 2015. View the proposal and related information.