Reza Ronaghi Lost her home in the Los Angeles wildfires last week.

“Not a single house on our two blocks survived,” he said.

Ronage is a pulmonologist at UCLA. As such, he's well aware of the health risks associated with inhaling wildfire smoke. But even he, a medical professional, was shocked to discover how many potential health risks lurked in the debris, ash and smoke left in the wake of fires.

"This wasn't just any fire," he said. "Thousands of homes and all the materials that went into building them, interiors, appliances, roofs, the list goes on."

But he was even more shocked that officials provided little health and safety guidance to residents who returned to the community to view the remains of their homes.

Days after the burn, he and several neighbors were allowed back into their Pacific Palisades neighborhood: the ground was still smoking. He wore an N95 mask, but soon realized he should protect himself more thoroughly—wearing gloves, goggles, respiratory mask Examples include clothing worn when handling chemicals, and long clothing that can be removed and bagged immediately after leaving the area.

After just 20 or 30 minutes, he said, his eyes were watering and his nose was inflamed. Later, he realized his skin was irritated from accidental exposure to debris and polluted air.

Previous scientific research has shown that debris left behind after fires can contain toxic compounds and gases, from heavy metals to burned plastics to asbestos. Exposure to volcanic ash or even air can cause short-term health effects, ranging from Lonergy's watery eyes to respiratory problems and more.

But Lonergy is concerned about more than just immediate health issues. He worries that the exposure people are experiencing now could lead to health effects in the future.

Exposure to the toxins left behind after a house burns "is actually much more dangerous to the lungs than the smoke," he said.

So when people return to their homes, he wants them to take care of them — because "right now, we're talking about long-term consequences."

The material you burn matters

Even if a fire primarily burns trees and vegetation, wildfire smoke and ash can pose risks to people's health. But fires that burn man-made materials are often filled with more toxic mixtures. Researchers find unusually high lead concentrations after 2018 Camp Fire in California downwind of burnthey suspected it came from a smoking house. Researchers in Los Angeles have initially found that volcanic ash there has High concentration of metals,besides. Exposure to lead can cause short-term problems such as headaches or dizziness. high exposure It has been linked to problems ranging from cognitive problems to reproductive and cardiovascular problems.

It's not just metal. Appliances, coolant, polyester curtains, cleaning products—all man-made parts of the house can produce abundant A range of compounds and gases that are hazardous to healths, such as benzene and formaldehyde, and polycyclic aromatic hydrocarbons (PAHs).

But research into the long-term effects of wildfire smoke has only begun recently. post investigation Lahaina wildfire 2023 found an increase in heart, kidney and mental health problems among residents exposed to smoke and ash. one EPA-led research Mice were exposed to smoke from military burn pits, which included many of the materials that might be found in burning homes and cars; mice exposed to the smoke showed signs of inflammation and lung damage.

In the most damaged and contaminated areas, officials often send in debris removal teams to clean up The most dangerous waste and ash. But Ronaghi stressed that anyone visiting the area before this process is complete should take precautions.

He recommends that anyone visiting a burn site use an N95 mask or respirator (if possible) and wear goggles to protect their eyes (ski or swimming goggles can work in a pinch, he said); gloves; and that they Long clothing that can be removed before returning to your accommodation. Other experts recommend bagging these garments during transport and laundering them immediately upon returning home to avoid introducing dangers into your living space.

Even those whose homes are still intact, including those far from the front lines of the fires, may be battling ash and smoke. Joost de Gouw, an atmospheric chemist at the University of Colorado Boulder, said research conducted after the 2021 Marshall Fire in Boulder, Colorado, found that in homes downwind from the fire, “smoke successfully penetrated indoors and through cracks under doors and windows Come indoors”. and the author of one of the studies. Resident reports health disordersA few weeks later, everything went from headaches to respiratory problems.

After the Marshall Fire, harmful gases associated with wildfire smoke, such as benzene and naphthalene, could still be detected in homes downwind from the fire long after the fire was extinguished. Another study suggests that these gases may be absorbed by textiles, mattresses, and even wood framing and drywall in your home.

It will take some time for the gases to dissipate, during which time residents may still be exposed, DeGouve said.

After a fire, "all the gases that were absorbed into the building materials are slowly re-released through the indoor air, and you can smell them in the indoor air," he said. "The process took about five weeks before everything was ventilated again."

How to clean

Even for those far from burned neighborhoods, cleanup efforts can be dangerous and could last for weeks.

Because residual ash and smoke can contain dangerous ingredients, experts interviewed by NPR recommend that if your home has been affected by wildfire smoke, protect yourself thoroughly every time you clean your home.

"People returning to these homes should wear N95 masks to protect themselves," said Colleen Reid, a health geographer at the University of Colorado Boulder who was involved in the Marshall Fire smoke study. "We found that when people clean , it resuspends the ash," bringing it back into the air where people may inhale it.

Reed also recommends wearing gloves, long sleeves and pants when cleaning.

She said scientists are still working to come up with rigorously tested recommendations on best cleaning practices after wildfires. But a 2023 study showed that cleaning hard surfaces in homes Dust, wipe and mop with a damp cloth It can effectively reduce the concentration of gas associated with smoke.

Reed recommends "using a HEPA vacuum filter and really cleaning all the surfaces, like wiping them down, to try to remove those sources of chemicals that are off-gassing."

Porous surfaces, like sofas and other textiles, can be an ongoing source of exposure; Reed recommends replacing them if possible.

de Gouw and other researchers found that continuously operating air filters activated carbon Reduced gas concentrations in the first weeks after a fire. But when the air filters stopped functioning, concentrations went back up, so "it's important to keep them running during those weeks," he said.

Research from Portland State University found that post-fire PAH levels can be reduced by: Simple cleaning and laundering of any washable textile. Long-term exposure to PAHs and Increased risk of cancer.

The message, de Gouw said, is to clean everything you can clean carefully and thoroughly, as smoke can affect nearly every part of a home, even those far from the line of fire. He said any efforts to reduce doses of potentially dangerous smoke and ash byproducts would help protect people.

Ronaghi is still dealing with the aftermath of the fire. Currently, his family is dealing with the loss of their home and considering how and where to rebuild their lives.

But in the process, he wants to make sure others understand the ongoing risks.

"Most of the time we hear about fires, we say, well, you know, we're going to be fine. We kind of stay out of it," he said. But for people across Los Angeles right now, there’s a good chance they’re being exposed to health-damaging toxins. "And you won't know for a long, long time," he said. "That's why it's so important to protect yourself."