For Valley air quality some highs, some lows, some questions

A lot can happen in a year. Sometimes little can happen in a year’s time and it has, that is, air-quality-wise in California’s San Joaquin Valley, apparently. And, that can be good or bad news. It just depends on one’s point of view.

The San Joaquin Valley Air Pollution Control District (air district) is out with its “Report to the Community: 2014-15 Edition” document.

Based on reported findings, air in the Valley is a mixed bag. Here are several report highlights as reported by the air district:

“Using a neighborhood-by-neighborhood accounting for population exposure to ozone concentrations, Valley residents were exposed to ozone concentrations above the standards for the fewest number of days to date from 2012 through 2014. In fact, the average number of days a resident experienced ozone levels above the 1997 and 2008 8-hour ozone standards has been reduced by 91% and 73% respectively, since 2002.”

“The number of days when the 75 ppb [parts per billion] 8-hour ozone standard was exceeded anywhere in the Valley was the lowest to date during the typical peak ozone season of May through September.”

As for particulate matter smaller than 2.5 micrometers in diameter (PM 2.5), between 2012 and 2014, numbers took a turn for the worse. The 24-hour PM 2.5 design value trend rose from roughly 58 micrograms per cubic meter of air in 2012 to approximately 69 micrograms in 2014. As for the annual PM 2.5 design value trend, in 2012 in the Valley, PM 2.5 weighed in at 16 micrograms per cubic meter. This compares to 2014’s nearly 20-micrograms-per-cubic-meter-of-air-PM 2.5 concentration.

Sixty-five and 35 micrograms per cubic meter of air represent the average 24-hour 1997 and 2006 federal PM 2.5 standards, respectively, while the average annual 1997 and 2013 federal PM 2.5 standards are 15 and 12 micrograms per cubic meter, respectively. Please note, however, in the former case, attainment of the less health-protective 1997 standard of 65 micrograms per cubic meter of air was reached during the front part of but not maintained throughout the entire 2012-2014 period.¹

Indications are, though, the drought is a main contributing cause of the degradation of Valley air, or so it would seem.

The air district observed: “In addition to the low precipitation levels, the Valley also experienced long periods of atmospheric stagnation caused by temperature inversions. The combination of these conditions led to elevated PM2.5 concentrations throughout the Valley during late 2013 and early 2014.”

Adding, “[w]ith the inability to demonstrate attainment of the 1997 standards by the end of 2014, and in conjunction with recent litigation against EPA [Environmental Protection Agency] regarding its implementation of the Clean Air Act for PM2.5 standards, the District is now in the process of requesting time extensions for showing attainment of both the 1997 and 2006 PM2.5 standards.”

So, one has to wonder if atmospheric conditions in the Valley being what they are, are influencing trends in ozone and fine particulate matter in different ways or even at all.

Looking at the California Environmental Protection Agency Air Resources Board’s (ARB) ozone standard data, for years 2012, 2013 and 2014, respectively, for:

• California 1-hour ozone standard, exceedance days total 72, 41 and 48
• California 8-hour ozone, exceedance days total 134, 112 and 128
• National 8-hour ozone, exceedance days total 105, 89 and 87

Though, as the ARB notes, 2014’s numbers are preliminary.

Interesting to note is that meteorological conditions in the Valley in 2014 were a near carbon copy of those in 2013 or nearly identical, in other words – there wasn’t much variation from one year to the next.

Meanwhile, in providing comment regarding ozone status, the air district relates: “This historic ozone progress has only been made possible through the significant investment and sacrifice of Valley businesses and residents to reduce air pollution. Recognition of these efforts lends credibility to the effective strategies that have been used and builds a stronger foundation for additional work that remains in continuing to make progress toward meeting other air quality standards.”

With this news, mixed as it is, much air-quality improvement work in the San Joaquin Valley remains.

Notes

1. “Report to the Community: 2014-15 Edition,” San Joaquin Valley Air Pollution Control District, p. 6.

Department of corrections: Above in the blog post, it was originally stated that: “In no case was even the less health-protective 1997 standard ever met in this three-year span.” This statement has since been revised with the appropriate correction added.

Bottom image: NASA

– Alan Kandel