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

Los Angeles has been given the infamous and ignominious distinction of being labeled the smog capital of the United States. Combining harm with insult, it was in the early 1940s that the scourge first emerged in the southern region of the state. In the early 40s!

Although there are still dangerous episodes of smog that arise from time to time in the southern region, today it is not as frequent or as problematic compared to what it was before.

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

“Los Angeles will once again be among the worst in the country for ozone. While we have made enormous progress in cleaning the air over the past few decades, including significant reductions in unhealthy ozone days, our fight for clean air is far from over.

“South Coast AQMD has worked hard to pass 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-emission technology in all commercial, industrial and residential sectors where currently available and which aims to reduce emissions by 70 percent by 2037. Continue investing in clean technologies.”

Skipping a paragraph, the AQMD in the statement added: “The majority of smog-forming emissions that contribute to elevated ozone and PM 2.5 levels in our region come primarily from heavy-duty mobile sources: trucks, ships, airplanes, locomotives and construction equipment under federal authority. Our journey toward cleaner air requires us to come together at the local, state, and federal levels 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 large amount of land. About half of California’s 40 million residents reside there.

The southern region is a vast center of commerce. About 40 percent of all the country’s import business is funneled through the combined ports of Los Angeles and Long Beach. The air pollution contributed to this is considerable. Now let’s add everything that comes from transportation, refining, power generation, industry, manufacturing, agriculture, residential and commercial activity, both port and non-port, and it is easy to see how, with certain meteorological and topographical conditions , With air stagnant under a high-pressure dome heated by the sun, skies with relatively clean air can turn a dirty brown or gray in the blink of an eye. A large number of people around the world know this very well.

Well, the figures for pollution by fine particles (PM2.5, particles less than 2.5 micrometers in aerodynamic diameter) and ozone (O3) for two years (2023 and 2015) are compared here in order to show them in terms of improvement of air quality. what progress has been made in the South Coast Air Basin between those two years.

Regarding the daily average number of the south coast air basin. PM2.5 at the highest site (in) 2023*, for six days, exceedances were recorded. This is compared to 2015, when in 39 days there were exceedance readings**.(1)

And now, the ozone. For multi-year ozone for the South Coast Air Basin ending in 2024*, for all of 2023, with respect to the national standard of 8 hours (0.070 parts per million), the number of exceedance days amounted to 117.

Meanwhile, in 2015, 113 national 8-hour ozone exceedance days** were recorded.(1)

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

Just for your information, although preliminary, the highest number of days of leave was recorded in 2020. That year there were 157.

And why compare 2023 and 2015?

Twenty-five was about three years after the end of the Great Recession and conditions were almost back to normal. Twenty-twenty-three is, well, post-pandemic, and here again, conditions had, for all intents and purposes, normalized as well.

In case you don’t know, similar numbers were presented for the state’s San Joaquin Valley region in the previous post, which was titled: “SJValley Air: Good or Bad? “It depends on who you ask.”


1. Data from CalEPA Air Resources Board

*Figures for 2023 may be preliminary.

** An excess corresponds to air quality in the range Unhealthy for sensitive people 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 commercial, industrial and residential sectors where “It is currently available and aims to reduce emissions by 70 percent by 2030.” The cited date of 2030 was incorrect. The date in question is now read correctly.

Update: June 7, 2024 at 4:54 pm PDT.

Featured image from corresponding and connected home page: United States Coast Guard, PA3 Louis Hebert

—Alan Kandel

Copyrighted material.



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