Some gas lines were still burning in Altadena, California, after the Eaton Fire moved through a burned-out neighborhood. Crews were working to shut off gas to the area. Smoke and ash from Los Angeles area fires blanketed the area. Experts suggest using caution when cleaning, even away from the immediate burn areas.
Ryan Kellman/NPR
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Ryan Kellman/NPR
Air quality in Los Angeles has improved as the Palisades and Eaton wildfires are brought under control. But as the fires ravaged homes, cars and industrial areas, they spewed large quantities of waste. smoke, ashes and harmful gases which spread throughout the city.
Indicators like Air Quality Index (AQI)commonly used to track air pollution levels, give a rough idea of the pollution floating in the sky. But these types of indicators don’t take into account some of the other potentially health-damaging materials in the air and released during fires. And many Angelenos are wondering how to assess their health risks.
NPR spoke with wildfire health and smoke experts to answer some basic questions.
What does the AQI tell us and how is it measured?
The AQI incorporates measurements of five different air pollutants regulated by the Environmental Protection Agency: fine particulate matter, ozone, carbon monoxide, sulfur dioxide, and nitrogen dioxide. Decades of health science have demonstrated that these pollutants harm the health of those who breathe them regularly. The AQI was designed to represent health risks from common pollutants, such as car exhaust or smog.
The EPA collects data for the AQI from approximately 4,000 air quality monitoring stations across the country. But air quality can vary on a hyperlocal scale, meaning the network of official sites is “pretty sparse,” says Michael Jarrettair pollution expert at the University of California, Los Angeles.
“They don’t have the spatial density or sometimes even the temporal density to tell us what’s actually happening at the localized level that really matters to people,” he says.
The EPA has created six color-coded categories ranging from green (good, when the AQI is below 50) to Bordeaux (dangerous, when the metric exceeds 301, as is often the case near active wildfires). Although Jerrett says “good” is a bit of a misnomer because even low levels of exposure has air pollution is associated with health problems.
What doesn’t the AQI tell us?
The air quality index does not take into account many contaminating gases or particles produced during wildfires, especially when homes, cars and other man-made materials catch fire. Homes, for example, are full of synthetic materials (think sofas and mattresses), as well as appliances, coolants, metal wiring, asbestos tiles, lead paint, and many other materials that can generate dangerous pollutants.
Man-made materials produce smoke laden with toxic compounds when they burn.
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Chris Pizzello/AP Photo
“They emit more toxic materials per unit burned than vegetation,” explains Colleen Reidhealth geographer who studied wildfire smoke at the University of Colorado Boulder.
Researchers conducted experiments simulating houses on fire and measured carcinogens such as benzene or formaldehyde that developed in the smoke. with a long list other harmful materials. They mice exposed to smoke. “It is more toxic to animals that breathe it than urban air pollution or wildfire smoke from biomass fuel alone,” says Luc Montrosewildfire smoke expert and environmental toxicologist at Colorado State University.
Most of these potentially harmful gases and particles go unmonitored in most of the United States.
If the AQI is “good”, should I still be concerned?
Smoke conditions in the Los Angeles area have improved as fires become more contained and winds redirect smoke away from the Los Angeles basin. AQI readings have reported “good” conditions in recent days.
But the remnants of smoke and ash that covered the city are still settling, and they pose ongoing risks, Jerrett said.
He recommends using the AQI as an indicator of the amount of potential pollution in the air. New smoke could appear quickly if wind patterns change, and potentially toxic ash that spread across the city at the start of the fires may also be released into the air by the wind.
Because the EPA’s sensors are widely spaced, several experts suggest keeping track of more localized data, like the PurpleAir network, which measures fine particles in the air. The data comes from small sensors that people can buy and place near their homes; there are thousands in the Los Angeles area. Accuracy is lower than regulatory monitors, but updates every two minuteswhile regulatory observers report an average over several hours or a full day.
Or, Montrose suggests, you can even buy personal air quality monitors, small enough to hang on a backpack.
“Knowledge is power,” he says.
Personal air monitors will not tell you what toxic contaminants are in the air. But the measurements can give you a general idea of risk.
How can I protect myself and my family from potentially dangerous air?
Even when wildfire smoke comes primarily from trees or plants rather than man-made materials, it causes serious health consequences. Recent analyzes suggest it is a factor in some 16,000 untold deaths Each year in the United States, smoke exposure is rarely considered the leading cause of death, but the added stress on people’s bodies can have such a drastic impact on their existing health problems, in some cases, that it leads to premature death.
Exposure to wildfire smoke has also been linked to higher risks of cardiovascular problemsmental health problems, skin problems and the worsening of respiratory diseases.
Toxicologists have a common saying: the dose makes the poison. So the main objective, says Lisa Patelpediatrics expert at Stanford University and member of the Science Moms group, is to reduce your dose. “Trust your nose,” says Patel. “So if you smell that pollution, go ahead and put that mask on.”
Ashes from the first days of the fires could be lifted again by wind or moving air. So Patel says if they’re concerned, parents might err on the side of caution and consider limiting their children’s outdoor activity time.
N95, KN95 and air filters for your home can protect you from fine solid pollution, including asbestos fibers. Gaseous components, such as benzene, are more difficult to process, but Joost de Gouwan atmospheric chemist at the University of Colorado at Boulder, suggests running air filters equipped with activated carbon.
As for schools, Patel says many schools have updated their HVAC systems during the COVID-19 pandemic. But if that’s not the case, she recommends helping by purchasing a portable air filter for your child’s classroom.
