At least six times this summer there has been a violation of the 8-hour ozone standard in the San Joaquin Valley which was not recorded. The most recent one was yesterday on 9/11.
These six violations have taken place at the site of the Arvin Bear Mtn monitor which operated between 1989 and 2010. That particular monitor recorded more violations of federal ozone standards than any other monitor in the valley during that time. That monitor was predicted by the Air Board to show compliance with federal health standards for ozone later than every other monitor in the valley.
The California Air Resources Board (CARB) jumped at the chance to remove this monitor when the Arvin Edison Water Storage District balked at renewing the long term lease allowing the monitor on their property. Our local Air Board stayed silent on the matter (we don’t know what was said behind the scenes), knowing it was to their benefit to have the monitor removed in the sense that there would be fewer air quality violations in the valley and they would not have to force local polluters into as many reductions of their foul emisssions.
Fortunately, in 2010, CARB set up another monitor not too far away at a site called Di Giorgio in order to compare its data to the Bear Mtn data. Both sites were out in the country southeast of Bakersfield and near the mountains. The Di Giorgio site was further from the hills in an area where the air could not stagnate as much as the Bear Mtn site. After the summer ozone season of 2010 the Bear Mtn monitor was taken down. Today we have the Di Giorgio data which is considerably and consistently lower in the levels of ozone being measured in the area. We know that during the summer of 2010 (May through October) the Bear Mtn ozone data averaged 11% higher than the Di Giorgio data.
Because of these joint recordings from 2010 we can confidently predict when Arvin Bear Mtn would have violated an ozone standard on the basis of this year’s Di Giorgio data. For this year we find that Bear Mtn would again have the most violations in the valley with 73 days of unhealthy air recorded as of September 11, 2012. The Ash Mtn monitor in Three Rivers is second with 71. What is also important from a statistical standpoint, is six of these violations occurred on days when there were no violations recorded elsewhere in the valley. That means the valley total as of 9/11 of 86 violations should really read 92.
Anyway, this has been a bad summer for ozone so far and it is actually worse than the numbers show.