The air in hundreds of United States cities is simply too dirty to breathe, which is why Wednesday the government ordered a multibillion dollar expansion of efforts to clean up smog. That order includes North Texas.

At issue is pollution from factories, automobiles and utilities. The new national rules will require cities to set policies to reduce ground-level ozone. The bad ozone, simply put, can make people gag and lead to chest pains, coughing and congestion.

Several counties in North Texas fall short of the Environmental Protection Agency's current standard for smog, which is 85 parts per billion. Dallas, Tarrant, Parker, Denton, Collin, and Johnson counties are on that list.

That picture doesn't get better under the revised standard. It allows for even less ozone in the air, 75 parts per billion. Ellis, Hood, Rockwall, and Hunt counties would also fail under the stricter standards.

Not everyone thinks the new standards are a good idea. A spokesperson for a utilities trade association was quoted as saying it will result in higher gas and utility prices. On the other side of the debate, an EPA advisory panel of scientists said the new standard should be even stricter.

States have until 2013 to submit proposals on how to improve the air in problem counties.

E-mail chawes@wfaa.com