Pollution over California’s Central Valley

[John Smith]

As seen from most of the way up Moro Rock in SEKI. You can even see what I believe to be Black's Peak in the Temblor Range, all the way across that soup of polluted air hanging over the valley.

[David K]

We noticed the air was looking quite bad as we drove north along I5 on Sunday. Is this from all the field work that is going on in the valley or are they burning ditches or rice paddies?

[David W.]

The Central Valley is consistently an EPA non-attainment area for smog and ozone. The main reason for the air polution is geography. There are mountain ranges on all of the valley and as a result pollutants get trapped. The EPA has been hammering on the Californa Air Resources Board and Regional Air Districts to improve the air quality or face penalties but there is little they can do. Agriculture is one of the main poluters but it is also the ecnonomic engine of the region. Regulating agriculture to imporve air quality would be politically unwise. There are two major north-south freeways in the valley that handle commerce. Trucking is another major polluter but can not be regulated by the local air districts. The weather is another factor. Is has been a dry winter with few storms to blow out the polution.

It sure is nice to get above in inversion layer and enjoy the clean Sierra air.

[Tipi Walter]

You guys should see the Tennessee Valley and the Smokies—it has air pollution as bad as LA. I know, I backpack thru the foul air all the time. And yet the head Park honchos won't stop cars from coming into the Park (about 10 million visitors a year) which sure wouldn't hurt to help in cleaning up the air. Every trip becomes a challenging attempt to avoid gulping in the crap. Hard to do when hauling weight up a mountain side.

[HkNewman]

+1 on the geography. Everywhere in the American west, if there's an agricultural valley, inhabitants burn agricultural wastes and also wood for fireplaces in the morning as the valleys serve as a cold sink as well. Add a built-up area and smog, you get pretty smokey inversion layers in cold weather. At a certain altitude, it stops but I've estimated that can sometimes be 6,000 ft or so on my every morning dayhike.

[Rick Dreher]

It begins with airborne pollution pushing in from the Bay Area, primarily sourced from transportation, electricity generation and manufacturing (especially refineries). Most of the year it turns right and heads south, into the San Joaquin Valley. Second is locally produced pollution–a combination of vehicles, manufacturing, electricity generation, agriculture and natural sources. Much of the year high pressure is parked above the region, creating an inversion and trapping all the crud.

In winter, it's particluates and in summer, ozone–the Central Valley is a non-attainment region for both. Interestingly, summertime ozone also pushes well into the mountains, creating health hazards and stressing forests.

This will be a big summer for forest fires, so that will be an added pollution source as well.

Breathe deep!

Rick

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