The wildfires raging across the Los Angeles landscape have destroyed many thousands of homes and buildings and damaged hundreds more.
And any property, experts warn, could pose a risk to Angelenos even long after the flames have died down.
As residents begin returning to their homes, toxic threats could lurk in everything they encounter, warned Chris Field, director of the Stanford Woods Institute for the Environment.
On Thursday, residents were warned at a press conference not to return to their homes because of these toxins. L.A. Public Works spokesperson Yonah Halpern said the Environmental Protection Agency (EPA) and county fire departments will go door-to-door to assess and remove hazardous materials.
Homes and cars contain a host of potentially hazardous materials, including lead, battery acid, arsenic and carcinogens in plastics. Such materials may be in the ash of a damaged structure, or may have drifted from adjacent properties. And anyone who searches or cleans a home without proper protection runs the risk of inhaling or absorbing the substances through the skin.
“The likelihood of toxic materials being present from things that were safe before the fire is very high,” Field said. “These toxic substances are in addition to the risk already created by simply being exposed to large amounts of ash and smoke.”
In the longer term, residents should also be aware of the risks of repeated natural disasters, especially mudslides, said Joshua West, a professor of earth sciences at the University of Southern California and an expert on debris flows, the scientific name for mudslides and similar sudden movements . of earth.
Wildfires increase the risk of mudslides by making a landscape vulnerable to rapid erosion in the event of a rainstorm, West explains. For example, in January 2018, severe storms that hit an area in Montecito that had burned in the weeks before caused a mudslide that killed 23 people.
While authorities have a pretty good idea of how to assess which areas are most at risk of a mudslide after a bushfire, the relative unpredictability of rainfall patterns means it’s not an exact science, West says.
“The storm that caused these debris flows dumped a tremendous amount of rainfall on the Montecito area,” West said.
Fortunately, Field and West say, there are a number of precautions property owners can take now and in the future.
Protect yourself from toxic risks
As Angelenos consider returning to their properties, West warns that they should always pay attention to authorities first and not return until an evacuation order has been lifted.
When a home is completely destroyed, Tracey Woodruff, an environmental health expert and director of the Earth Center at the University of California, San Francisco, likened the property to an “uncontrolled hazardous materials incinerator,” noting particularly hazardous materials such as pesticides and the lithium-ion batteries now common in home appliances and electric vehicles.
Even small pieces of glass can pose a risk if inhaled. Normally, cleanup of such properties is handled by professionals or emergency response teams due to all the inherent dangers, and California Governor Gavin Newsom announced on Tuesday that teams were indeed ready to carry out the work as quickly as possible.
While it may be tempting for residents to see if they can find souvenirs or salvageable items before a property is cleared by authorities, Woodruff said the risks outweighed the likelihood of anything being found.
“People who are going to clean up these types of properties wear hazmat suits,” she noted, adding that the extremely high temperatures of devastating fires made it very unlikely that valuables would have survived.
Anyone who ignores such advice or returns to a partially damaged property should take precautions, Field added. A well-fitting N-95 mask, goggles and gloves should be the minimum protection, he said, and a professional respirator and full-body Tyvek suit would be ideal. The Federal Emergency Management Agency also maintains a fact sheet with further advice on how to safely search a home for valuables.
Protective measures should be taken even in the event that a home appears to be untouched, Field added, because of the possibility that toxic smoke has entered from elsewhere.
“Smoke and toxic dust can actually form a layer of hazardous materials even on top of things that haven’t burned. Everyone has to be careful,” he said.
Field recommended using a water fogger to assist with cleanup or moving through an affected property to prevent potentially toxic dust from becoming airborne. Ideally, every material in a home should be treated as if it were covered with such material, and properly wiped or washed. And residents should check with local authorities on how to properly handle larger or hazardous materials.
Woodruff added that children should also not be taken because their developing bodies are more vulnerable to exposure to toxins.
The long-term threat of mudslides
Once the cleanup was completed, West warned that the risk of mudslides remained. Normally, the greatest danger occurs within the first year to two years after a wildfire, as the natural vegetation that holds the landscape together rebuilds. But extremely heavy rains or other unusual variables can make the risk last longer.
The U.S. Geological Survey has developed a tool called the Debris Flow Hazard Assessment Viewer, he said, which takes into account variables such as topography, burn severity and historical weather patterns to assess the level of risk in a given area. Such information is used by state and local authorities to plan for potential mudslides, but is also available to the public as initial assessments for the Palisades and Eaton fires are expected soon.
Such information can be used by a homeowner to determine the risk of mudslides. But West reiterated that it is not an exact science, as was the case in Montecito, where areas at the highest risk of mudslides suffered less damage than adjacent areas deemed at lower risk.
A homeowner could hire a professional geotechnical engineer to create a customized risk assessment for their property, West added. Typical protective measures include physical measures such as sandbags and earthen berms to direct any debris flows away from valuable areas of a property, and keeping an emergency kit ready in case an evacuation order is issued. The California Department of Public Health offers additional preparedness tips.