Report: Five Smoggiest US Cities Are in California

And they’re not necessarily the ones you might guess

California may have great weather but also some of the nation’s worst air. The advocacy group Environment California has issued a report ranking the nation’s worst metropolitan areas for air quality. The five worst are in California, as are six of the top ten.

Smog in the Los Angeles Basin

Based on data from 2010, the report’s “Top Smoggiest Areas in the US” were:

1. Riverside-San Bernardino

2. Visalia-Tulare-Porterville

3. Bakersfield (tie)

3. Los Angeles-Long Beach (tie)

5. Fresno

The report tallies 110 “smog days” for worst-ranked Riverside-San Bernardino:

“…meaning that the area, home to more than 3 million residents, had unhealthy air on one out of three days in 2010. Twenty-four of those days were categorized as “red-alert days,” meaning that air quality was so poor that anyone could experience adverse health effects…”

This is a bit like golf. In this contest, a high score is not good. Among other California contenders in the top 20, Sacramento checked in at tenth (tied with St. Louis and Knoxville, TN; and San Luis Obispo-Atascadero-Paso Robles at 17th (tied with cities in New Jersey and the Carolinas). In a separate ranking of only “large metroplitan areas,” San Diego also makes the list, and the group’s ranking of “small” metro areas includes such geographically diverse California towns as Merced (tied for 2nd) and Chico-Paradise (tied for 16th), which is tucked into the foothills of the northern Sierra.

The 61-page report uses as its benchmark the (still in place) 2008 federal ozone standard for counting “smog days.” The information is parsed and sorted into several more lists by geography, metro area size, and time frame.

One of the main constituents of smog, nitrous oxide, is also a potent greenhouse gas, which contributes to global warming.

  • worse than predicted

    If you think that is bad, take a look at what the cost is of ground level ozone in terms of global warming:

    Makes your head spin. Too many people. Too many cars. Too much complacency.


  • Craig Miller

    Interesting site, Beth. Can you tell us who’s behind it, as it does not appear to have an “About us” page?

  • AnEngineer

    Many people, especially the regulators, overlook the fact that air moves quite readily so that the smoggiest places are not necessarily the place where the smog was produced. For example, the Bay Area Quality Management District is fairly lax with permitting emission sources because the fresh ocean breeze blows the NOx into the inland valley. The San Joaquin AQMD on the other hand, is stuck dealing with all the NOx created by the bay area and hence is extremely difficult to deal with. The result: bay area industries pollute and nobody cares, but agricultural businesses in the valley are fined for producing even the most trivial amount of NOx. Of course, pointing out this inconsistency gets you labeled as being an anti-environmentalist, so nothing is said.

  • Anonymous

    The biggest problem with California is that there are too many Californians!