Los Angeles Wildfire Air Quality Threatens Food Safety

The USDA warns that wildfires, such as those raging in the Los Angeles Area, can render food in homes unsafe to eat. And given that fires can release smoke plumes that reach up to 14 miles (23 kilometers) into the stratosphere— impacting households thousands of miles away— even homes that are relatively far from the vicinity of the fire could be at risk.

Driven by fierce Santa Ana winds and dry vegetation following an extended drought, wildfires erupted in Los Angeles on Tuesday Janury 7th, scorching tens of thousands of acres and going down in history as some of the most destructive wildfires in California’s history. Los Angeles County Sheriff Robert Luna described the devastation as resembling the aftermath of an atomic bomb.

Food poisoning occurs when individuals consume food or drinks contaminated with harmful bacteria, viruses, or other pathogens. Smoke fumes, extreme heat, as well as fire-fighting and other chemicals can introduce these harmful contaminants, affecting homes thousands of miles from the flames.

“Wildfires primarily affect the west coast and northern states in the United States,” says Mark Davidson, Manager of Marketing and Technical Materials at Camfil, a global provider of indoor air filtration solutions and clean air systems. “However, the smoke from these fires can be carried far and wide by the wind.”

Wildfire smoke is more toxic than typical air pollution, as it contains harmful gases and particulate matter from burning not only vegetation but also synthetic materials like plastics, rubber, and treated asphalt in buildings, cars, and homes. In Los Angeles, fine particulate matter recently peaked at dangerous levels of 40-100 micrograms per cubic meter— which is between 8 and 20 times the maximum recommended levels set by the World Health Organization.

The danger lies in the wildfire smoke itself. According to Camfil, more than 90% of the mass of wildfire smoke consists of PM2.5 particles— ultra fine pollutants smaller than 2.5 microns.

These particles can travel far on air currents, and harm residents miles away. They can infiltrate common food packaging, including plastic wrap, cardboard boxes, and screw-cap containers. Once contaminated, food cannot be decontaminated, posing risks to human health.

The Los Angeles Department of Public Health advises discarding plastic water bottles covered in ash, as particles can contaminate caps. Food exposed to ash and not stored in waterproof or airtight containers should also be thrown out, while sealed glass or metal jars can be cleaned and used.

Wildfires also emit harmful gases, such as nitrogen oxides and carcinogenic polycyclic aromatic hydrocarbons (PAHs) that, after infiltrating indoors— often through HVAC systems without adequate filtration— can accumulate on foods and food surfaces through particle deposition.

Camfil advises that household risks from wildfire smoke can be mitigated by utilizing “a combination of carbon filtration to control odor and gaseous contaminants and high efficiency air filters on PM2.5 particles.”

Because of their proximity to densely populated areas, the Los Angeles wildfires have destroyed thousands of structures. Fire-fighting and other chemicals released from combusted substances, such as building chemicals and plastics, can contaminate both food and cookware, leaving behind toxins that cannot be washed away.

Fires can cause chemicals to vaporize, turning them into gases, while others bind to particulate matter. The intense heat and combustion process can also alter existing chemicals, breaking them down or combining them into new, potentially harmful compounds.

Fire retardants like Phos-Chek used to control the wildfires in Los Angeles also contribute significant amounts of toxic metals to the environment, with 380,000 kg released in the U.S. between 2009 and 2021.

Heat from the wildfires further compounds the risks. Extreme temperatures can compromise the seals of cans and jars, allowing bacteria to infiltrate. In some cases, the heat activates dormant pathogens, significantly increasing the likelihood of foodborne illnesses.

And the risks don’t end there.

A study published in Ecosphere revealed that wildfire smoke can serve as a vehicle for bacteria and fungi, carrying microbial life across vast distances. Researchers exposed petri dishes to smoke at varying distances from a fire and identified more than 70 types of bacteria and fungi growing on the dishes, with microbial abundance decreasing as distance from the fire increased, raising concerns about the potential for wildfires to spread food borne pathogens.

Further research reveals that wildfires may contribute to food borne diseases by spreading heat-tolerant microbes to food. While wildfire flames typically reach temperatures of 300˚ to 1,100˚C, some soil-dwelling microbes can survive in extreme heat, with certain strains tolerating up to 800˚C.

Barbara Brown, Oklahoma State University Extension food specialist, advises that following a wildfire, fresh produce, raw foods, and any open containers exposed to fumes, water, or chemicals should be discarded to ensure safety. Similarly, pantry staples like flour, sugar, spices, and seasonings, along with items in non-airtight containers such as peel-off tops, screw-top jars, cardboard boxes, or those wrapped in foil, plastic, or cloth should be discarded. If there is a power outage, perishable items such as meat, seafood, milk, soft cheeses, eggs, prepared foods, and cookie dough must be thrown out if kept above 40°F for more than two hours.

Power outages often leave fridges and freezers full of spoiled, foul-smelling perishables. While many assume they can simply clean out the fridge, experts warn that food spoiled for even a few days can leave lingering contamination. In some cases, it may be safer to replace the fridge entirely.

As of Friday, there were hundreds of thousands of people in the Los Angeles area who had lost power to their homes. The number of people who have been displaced is approaching 200,000 and officials expect the death toll to rise in the coming days. Among the 6 active wildfires in Los Angeles county, the Palisades and Eaton fires have been recorded as the most destructive in California’s history.

The Los Angeles wildfires are a stark reminder of the far-reaching impacts of climate-related disasters, underscoring the fragility of our food systems and the urgent need for robust disaster preparedness. The connection between environmental disasters and food safety demands both immediate action and long-term solutions to protect public health.