Smoke from at least three fires in Los Angeles has caused unhealthy and hazardous air quality, causing school closures and official warnings.

“In my lifetime I have not seen something this destructive,” said Rachel Ibrahim, a student at the University of Californina, Los Angles (UCLA).

Forced to leave campus as the fires raced within five miles of the California university, Ibrahim told Health Policy Watch that it was “not healthy for us to be here while it was happening, while it was at its peak.”

Even in her home east of the city, the wildfires blew large quantities of ash and smoke, causing her family to leave the city for the weekend for Newport Beach “where the air quality was much, much better.”

The Eaton, Palisades, and Hurst fires, which roared through homes, businesses, and schools in the US city last Tuesday have sent billows of toxic smoke throughout the region. 

“Wildfire smoke is one of the most complex aerosol exposures that exists,” said Dr Daniel Croft, a pulmonologist and researcher at the University of Rochester. “The particles such as PM 2.5_, and gasses such as NO₂ have well established risks to respiratory disease like COPD [Chronic Obstructive Pulmonary Disease] and asthma and cardiovascular diseases like heart attack and stroke.”

Fine particulate matter that is 2.5 microns or less in diameter (PM 2.5) is the most concerning aspect of wildfire smoke. PM 2.5 from burning homes, cars, asphalt and other materials contain high levels of carcinogens, according to the University of Utah. Exposure to an AQI of 200, which much of LA reached last week, is equivalent to smoking five cigarettes. 

The fires, exacerbated by hurricane-force Santa Ana winds and extreme drought, are less than a third contained and have killed 24 people. Nearly 150,000 others have been forced to evacuate, and over 12,000 structures are destroyed. 

The spike in poor air quality caused the LA Unified School District to shut schools last week, universities to send students home, and public health officials to issue warnings about the danger of wildfire smoke. 

“Predicting where ash or soot from a fire will travel, or how winds will impact air quality, is difficult, so it’s important for everyone to stay aware of the air quality in your area, make plans, and take action to protect your health and your family’s health,” said Muntu Davis, MD, MPH, Health Officer for Los Angeles County in a press release Friday. 

“Smoke and ash can harm everyone, even those who are healthy. However, people at higher risk include children, older adults, pregnant individuals, and those with heart or lung conditions or weakened immune systems.”

Wildfire smoke: Gases, particles, and toxic chemicals

Wildfires can produce unhealthy, very unhealthy, or hazardous criteria levels of pollution – standards set by the US Environmental Protection Agency (EPA) Air Quality Index (AQI) to measure a range of particles and gases hazardous to human health. 

Wildfire smoke – a mix of gases, hazardous pollutants, water vapor, and particulate matter – can cause both short and long-term health effects.  This smoke is often undetectable, with no obvious smell or haze. 

“While the direct exposure to nearby wildfire smoke is a health risk, the smoke undergoes chemical changes as it travels in the air that can potentially even increase its toxicity to cities many miles away,” said Croft. 

Furthermore, “many homes were built prior to 1970 and have lead,” noted Martina Zaghloul, a physician associate student in LA. “So there’s a lot of toxins and lead particles in the air from the burning paints and plastics.”

The highest hourly level of PM 2.5 spiked at over 480 micrograms per cubic meter last Wednesday, as reported in the LA Times. The EPA limit for a daily average concentration is 35. 

The toxicity of these particles increases the risk of negative health impacts. Respiratory distress, asthma attacks, heart attacks, and strokes are all associated with wildfire smoke. Longer-term issues include adverse pregnancy outcomes, lung disease, cancer, and asthma. 

Wildfires ‘reversed’ clean air gains

Since the Clean Air Act of 1970 and stricter vehicle and factory emissions, air quality in the US has improved. However, this is being reversed by wildfires.

Researchers at Stanford write that in the past 10 years, wildfire events “dominate” dangerous particulate matter exceedances, and have eroded air quality by 50% in western states. 

Record-breaking wildfires in 2020 contributed 20-30% of particulate matter in the contiguous United States. 

Smoke can travel thousands of miles, degrading air quality, and spiking hospital admissions for asthma, respiratory distress, and heart attacks.

The Canadian wildfires of 2023, the effects of which were felt in New York City, triggered a nearly 20% increase in asthma emergency department visits, according to the US Centers for Disease Control and Prevention. 

Climate change, which has brought hotter temperatures and drought conditions, paired with a century of fire suppression policy has meant California has abundant fuel in arid conditions. Mitigation strategies urged on homeowners, like maintaining five feet of cleared vegetation around homes, is sometimes not enough to combat the intensity of these fires.  

This reversal in air quality gains is especially concerning to high-risk groups, such as children, older adults, pregnant people, and those with pre-existing health conditions.

Masking, staying indoors, using air filters

Wildfires on the scale of those in LA generate enough smoke to reach the atmosphere and travel thousands of miles, according to the EPA. This means that wildfire smoke poses a risk beyond the immediate region affected–and why the EPA and other health agencies recommend visiting sites like Airnow.gov to check local air quality conditions. 

The LA Public Health Department has urged everyone in areas where there is “visible smoke or the smell of smoke or unhealthy air quality” to avoid unnecessary outdoor exposure and to limit physical exertion. 

The department also recommends those in sensitive groups stay indoors as much as possible even in areas where smoke, soot, or ash cannot be seen or “there is no smell of smoke,” noting in a statement to Health Policy Watch that its guidance extends beyond wildfire burn areas and ash.”

Wind conditions remain variable, but for now, the LA Unified School District has reopened schools as air quality appears to have improved over the weekend for the city. “Kids are back in school and they still have to leave their homes, meaning they are exposed even if the air filters have been changed out,” said Zaghloul. “These particles are still travelling, making it difficult to protect yourself.”

This is a developing story. For more information, visit CalFire.

Image Credits: Daria Devyatkina/Flickr, CalFire, NASA/JPL-Caltech, EPA, U.S. Interagency Wildland Fire Air Quality Response Program.