Ozone-cleanup progress in Calif. South Coast Air Basin a mixed bag?

Los Angeles has been given the infamous, inglorious distinction of being labeled as the smog capital of the United States. Coupling injury with insult, it was in the early 1940s when the scourge first surfaced in the south-state region. The early 1940s!

Though there are still dangerous smog episodes that crop up from time to time in the southland region, it’s not as prevalent or as problematic today compared to what it once was.

Here is some of what the South Coast Air Quality Management District had to say in its Apr. 24, 2024 “South Coast AQMD Statement on the American Lung Association’s 25th State of the Air Report” press release.

“Los Angeles will again be among the worst in the nation for ozone. While we have made tremendous gains in cleaning the air over the past several decades, including significant reductions in unhealthy ozone days, our fight for clean air is far from over.

“South Coast AQMD has been hard at work passing the strictest regulations in the country on the stationary sources we regulate such as factories, refineries, and power plants. . . . Our 2022 air quality management plan is the most ambitious regional plan to date and the first to rely on zero-emissions technology across all business, industry, and residential sectors where currently available that aims to reduce emissions by 70 percent by 2037. And, we continue to invest in clean technologies.”

Skipping a paragraph, the AQMD in the release added: “Most of the smog-forming emissions contributing to elevated ozone and PM 2.5 levels in our region are primarily from heavy-duty mobile sources – trucks, ships, planes, locomotives and construction equipment under federal authority. Our journey toward cleaner air demands that we come together on a local, state and federal level to develop solutions so that hopefully, one day, Los Angeles will no longer top the State of the Air Report.”

By the numbers*

The South Coast Air Basin covers a lot of ground. Approximately half of California’s 40 million residents reside there.

The southland region is a vast center of trade. Roughly 40 percent of the nation’s entire import business is channeled through the combined ports of Los Angeles and Long Beach. Contributed air pollution connected with that is considerable. Now add in all of that which comes from linked-port and non-port-linked area transportation, refining, energy generation, industry, manufacturing, agriculture, residential and business activity and it’s easy to see how, with certain meteorologic, topographic conditions, stagnant air sitting under a dome of high pressure warmed by the sun, relatively clean-air skies can turn a dingy brown or gray in the virtual blink of an eye. Vast numbers of people all across the globe are well aware of this.

Okay, so fine particulate matter (PM2.5 — particulate matter smaller than 2.5 micrometers in aerodynamic diameter) and ozone (O3) pollution numbers for two years — 2023 and 2015 — are compared here for the purpose of showing in air-quality improvement terms what progress in the South Coast Air Basin between those two years has been made.

As for the number of South Coast Air Basin Daily Avg. PM2.5 at Highest Site [in] 2023*, on six days, exceedances were recorded. This compares with year 2015 when on 39 days, there were exceedance** readings.[1]

And now, ozone. For Multiyear Ozone for the South Coast Air Basin Ending in 2024*, for all of 2023, regarding the national 8-hour (0.070 parts per million) standard, the number of exceedance days totaled 117.

In 2015, meanwhile, there were 113 national 8-hour ozone exceedance** days recorded.[1]

As to that last number, this is surprising considering the number of exceedance days was higher in 2023 than it was in 2015.

Just for your information, though preliminary, the highest number of exceedance days was registered in 2020. That year there were 157.

And why compare 2023 and 2015?

Twenty fifteen was three years or so after the end of the Great Recession and conditions had returned to near normal. Twenty twenty-three is, well, post-pandemic, and here again, conditions had, for all intents and purposes, normalized as well.

In case you’re unaware, similar numbers were presented for the state’s San Joaquin Valley region in the prior post, which bears the title: “SJValley air: Good or bad? Depends on who you ask.

Notes

1. CalEPA Air Resources Board data

* Numbers for 2023 may be preliminary.

** An exceedence corresponds to air quality in the Unhealthful for Sensitive Individuals range or worse.

In an earlier version there was this quote: “Our 2022 air quality management plan is the most ambitious regional plan to date and the first to rely on zero-emissions technology across all business, industry, and residential sectors where currently available that aims to reduce emissions by 70 percent by 2030.” The so-cited date of 2030 was incorrect. The date in question now reads correctly.

Update: Jun. 7, 2024 at 4:54 p.m. PDT.

Corresponding, connected home-page-featured image: United States Coast Guard, PA3 Louis Hebert

— Alan Kandel

Copyrighted material.

Leave a Comment