Fact Checking CARB's Mary Nichols re “Nevada County worst (rural) ozone in the nation

In short: The lady - doubted by some (Steele, KPruett) - was correct.

In the aftermath to last month's CARB Chair Mary D. Nichols talk on AB32, Kim Pruett and Russ Steele wanted evidence for her assertion that Nevada County's air quality was the worst of any rural county in the U.S. and worse than any region nationally outside of California.

I offered to look into it, which entailed a) asking her office for the reference & b) getting stymied when looking into it myself, by not looking into the document that turned out to hold the rankings.

But CARB came through, in the person of a Mr. Chris Bowman:

"In recent years, the American Lung Association has ranked Nevada County as the most ozone-polluted rural area in the nation -- and smoggier than any city outside of California and Texas. The rankings come from the ALA's annual State of the Air reports...
In 2007, for example, you'll see (p. 24) that Nevada County ranked as the 13th most ozone-polluted county in the nation. This year, Nevada County ranked 8th (p. 16).
What's striking, of course, is that Nevada County has but a fraction of the population of every higher ranking county -- including El Dorado, Tulare and Kern, where the highest ozone readings are in urban areas such as El Dorado Hills, Placerville, Visalia and Bakersfield.
The disparity begs explanation. I went searching for answers seven years ago as a reporter for The Sacramento Bee and wrote a story on what I learned...

(Thank you Chris.)

From the aforementioned 2010 A.L.A. air quality report (pdf), p. 16, the nation's "worst ozone" county rankings are:

1. San Bernardino
2. Riverside
3. Kern
4. Tulare
5. Los Angeles
6. Fresno
7. El Dorado
8. Nevada
   

A couple of details: our county's population size is just over half of the least-populated "worse" county, El Dorado, with which we're almost tied for bad air at 45 vs 47 (weighted average of #unhealthy high ozone days, 2006-2008). And #1 San Bernardino, with 20x more people, had 3x more bad ozone days.