It sounds like it’s going to be almost impossible for any city to get to that 60 to 70 ppb 8 hr reading. Evidently in many rural areas background readings during the summer months are often above 75 ppb. Dallas is not even in the top ten US metro areas for ozone levels:
Know where your city stands. The American Lung Association’s State of the Air 2010 lists these 10 cities as the country’s most polluted by ozone:
1.Los Angeles, Calif., metropolitan area (including Long Beach and Riverside)
2.Bakersfield, Calif.
3.Visalia and Porterville, Calif.
4.Fresno and Madera, Calif.
5.Sacramento, Calif., metropolitan area (including Arden-Arcade and Yuba City)
6.Hanford and Corcoran, Calif.
7.Houston, Texas, metropolitan area (including Baytown and Huntsville)
8.San Diego, Calif., metropolitan area (including Carlsbad and San Marcos)
9.San Luis Obispo and Paso Robles, Calif.
10.Charlotte, N.C., metropolitan area (including Gastonia and Salisbury)
Another power play by the EPA which needs to be slapped down. They’ve got TExas in their sights. , Perry has done a lot of tough talking recently, let’s see if he’s actually grown a pair.
>>Evidently in many rural areas background readings during the summer months are often above 75 ppb.
Apparently trees play some role. Atlanta has had problems with the EPA over ozone often during the summer, and a large part of the reason is all of the trees here.
An article on the general subject:
Biogenic Ozone-Precursors: From Mechanism to Algorithm
http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/abstract/696/report/0