The western United States is baking under high temperatures right now. Along the Pacific coast, for the most part, the heat is not nearly as oppressive as it is farther inland.
Meanwhile, in California’s San Joaquin Valley, along with triple digit temps has come a spike in air pollution levels. By comparison, in the Central Los Angeles region today, located about 100 miles south of the southern San Joaquin Valley town of Bakersfield, ozone (smog) concentrations are low, meaning ozone is not problematic and air quality in this regard is good.
At roughly 25,000 square miles, the Valley consists of eight counties essentially ringed by the Sacramento Valley to the north, the Sierra Nevada mountains on the east, the Pacific Coast Range on the west and the Tehachapi and Tejon ranges on the south. Focusing on Fresno County on Sun., June 30, the Air Quality Index (AQI) was evidently 106 or in the “Unhealthy for sensitive groups” range. The AQI for Fresno County, presumably, was in the same range on Mon., Jul. 1 and, for today, the story is much the same, though temps are predicted to be higher today (111 degrees) than what they were yesterday (108 degrees).
What is known: Measured in parts per million (ppm), yesterday’s national 8-hour ozone standard of 0.075 ppm was exceeded by 0.013 ppm in the San Joaquin Valley or 0.088 ppm.
1-hour, 8-hour ozone standards
In the San Joaquin Valley Air Basin at this point in time 2013 versus 2012, tied at 29 are exceedances of the National 8-hour ozone standard. As for both California 1-hour and 8-hour ozone standards, the two are lower in the Valley this year compared to last – 14 (2013) versus 17 (2012) and 38 (2013) versus 41 (2012), respectively. Data though for 2013 is preliminary.
The good news is that compared to 2012 so far, 2013 is shaping up to be no worse in these respects. But, it is still way too early to draw conclusions because Valley ozone Exceedance Days could quite possibly occur even into and through November.
Meanwhile, in all of 2012, preliminarily speaking, there were a total of 105 Exceedance Days of the National 8-hour ozone standard.
National 8-hour ozone health standard-wise, the South Coast Air Basin so far this year has only one more exceedance at 44 compared to its 43 last year. However, in 2013 so far and with respect to California 1-hour and 8-hour ozone standards, there are 31 and 54 exceedances, respectively. Here again, data for 2013 is preliminary. This compares to 37 and 57 state 1-hour and 8-hour ozone exceedances, respectively, for 2012 at this time. So, with respect to the California standards, within the South Coast Air Basin as of this date, there looks to be improvement.
Nevertheless, it remains to be seen how the rest of the ozone season plays out in the two air districts. Keep posted as I plan on providing updates regularly.
Image above: U.S. National Archives and Records Administration