Amid Wildfires, Los Angeles Registers Highest Ozone Pollution in 26 Years

Two spectators watch smoke generated by the Bobcat Fire in San Dimas, Calif., Wednesday. (AP Photo/Jae C. Hong)

LOS ANGELES (CN) — Over the Labor Day weekend, downtown Los Angeles recorded the highest ozone pollution in the last 26 years as multiple wildfires burn thousands of acres and force many to flee their homes. 

Even more wildfires are burning across the West Coast, with an orange hue hanging over San Francisco and 23 reported dead across California and Oregon.

The South Coast Air Quality Management District, the agency that tracks air quality for Southern California, recorded the highest ozone or smog pollution reading since 1994 for Los Angeles over the weekend. The record-breaking data was first reported by the Los Angeles Times on Thursday.

On Sunday, the hourly reading for downtown LA was 185 parts per billion, according to the agency.

“The 8-hour average at Mission Viejo was 123 ppb, which is the highest 8-hour average ever recorded in Mission Viejo since monitoring began in 2000,” said AQMD spokesperson Bradley Whitaker. “Compton recorded an 8-hour average of 115 ppb, which is the highest value in Compton since monitoring began in 2008.”

Ozone is a secondary pollutant formed when precursor gases react to sunlight and can also warm the atmosphere. Typical sources that contribute to ozone include vehicle exhaust, industrial machinery and other human activity.

High temperatures and wildfires can contribute to the jump in recorded ground-level ozone or smog levels.

Forest fires have been burning across the southern California region since late July, starting with the Apple Fire in San Bernardino County and the Lake Fire ignited in the Angeles National Forest in Los Angeles County on Aug. 12.

As of Thursday, the Bobcat Fire has burned over 23,000 acres in the Angeles National Forest, north of the city of Duarte. The El Dorado Fire has burned over 12,000 acres in nearby San Bernardino County. Both fires started in the last few weeks.

Pyrocumulonimbus clouds, the large mushroom-looking clouds that form from wildfires, can send smoke high enough to impact the ozone layer, while elevated surface ozone levels can make it hard for people to breathe, especially for sensitive groups.

In the Southland, AQMD and the LA County Public Health Department have issued smoke advisories due to the wildfires that are sending ash and smoke miles away from their origin points.

“It is difficult to tell where smoke, ash or soot from a fire will go, or how winds will affect the level of these particles in the air, so we ask everyone to remember that smoke and ash can be harmful to health, even for people who are healthy,” said LA County Health Officer Dr. Muntu Davis.

Small particles found in wildfire smoke are the main cause of irritation in the throat and eyes, along with causing people to experience a runny nose, headache and other health symptoms, according to the county health agency.

High ozone levels can also be bolstered by extreme heat, like what LA County experienced over the Labor Day weekend. The city of Woodland Hills reported record-breaking 121-degree weather on Sunday.

During the heatwave across the Southland, winds were weak and conditions were stagnant and that led to a lack of strong ventilation, according to Whitaker from AQMD. Ozone pollution has begun to subside as the temperatures have dropped.

Earlier this week, California Governor Gavin Newsom said during a wildfire briefing, “I have no patience, I say this lovingly, not as an ideologue, but as someone who prides himself on being open to argument interested in evidence, but I quite literally have no patience for climate change deniers.”

According to the California Department of Forestry and Fire Protection, 29 major wildfires are burning across the state. This includes six of the 20 largest wildfires in the state’s recorded history.

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