When Kate Gammon and her family fled their home in Santa Monica, California, during the recent wildfires, they had no idea what they would find when they returned.

Although he was not under an evacuation order, Gammon, who has asthma, told CBC News that the air quality was deteriorating rapidly and the fire was uncontrollable, so he left on Jan. 8, when the fire was about six kilometers away. Four days later, he returned to find that the house had not been burnt down, but he was horrified to see ashes in his yard.

“It’s just that it’s raining at night,” he said. “They’re like big, white, bulky pieces of ash.”

Researchers now say that because of the size of these wildfires and the types of buildings that are burning, people who return home after a fire may still experience health problems from chemicals in the ash and smoke.

State firefighters are still working to contain the massive fire in Altadena and Pacific Palisades, which has killed at least 27 people and destroyed more than 12,000 homes including homes, schools and banks. Thursday, a Los Angeles County Health Office prohibiting cleanup or removal of flammable debris until a hazardous materials assessment is completed.

Ashes and dirt in household waste and house fires may contain asbestos, heavy metal and other dangerous thingsthe health director said, noting that people can be affected by toxic substances by inhaling ash or small particles of fire dust, or coming into contact with the skin or drinking contaminated water.

As an environmental reporter, Gammon has done it before reports on health hazards caused by ash, not only from the brush, but also from thousands of burned buildings. That’s why he says he avoids touching the ashes and wears a mask outside.

Earlier this week, scientists published their findings about how wildfires that burn wildlands and rural areas can affect indoor air quality. They learned 2021 Marshall Fire in Boulder, Colo., where nearly 1,000 homes burned in eight hours, which would help shed light on urban fires like the one in LA.

Post fire headache, itching eyes

Colleen Reid, a professor at the University of Colorado, studied health outcomes among people who returned to unburnt homes after the fire. He and his friends searched for people who lived near the burnt houses.

About five weeks later, they measured the concentration of volatile organic compounds (VOCs) in a house that survived the fire, but was heavily affected by smoke.

They found that excess VOCs persisted for about a month in the home before returning to the home itself.

“People who said their house smelled different six months after the fire started to have headaches, dry cough, itching, watery eyes, bad taste in the mouth and sneezing,” said Reid, an environmental epidemiologist.

SEE | Ashes from wildfires, smoke settles in unburnt buildings:

Toxic toxins from the wildfires remain in the remaining buildings

As evacuees in Los Angeles begin to consider returning home, studies show that the toxic effects of wildfires in the city can last for months in homes that survive the fire.

Reid and his team also surveyed people six months after the fire (642 respondents) and one year later (413 respondents). Results included:

• 65 percent of respondents reported that there was ash in their homes after the fire.

• Most respondents were less confident about the air quality in their home and community six months after the fire. Most regained self-confidence within a year.

Tips for cleaning up after a wildfire

Delphine Farmer, a Canadian scientist at Colorado State University, studies indoor air as part of the to try at the US National Institute of Standards and Technology in Gaithersburg, Md., where he and his team analyzed the structure of particles inside a converted home laboratory after introducing smoke from a fire.

The farmer found that The smoke covers itself on the painted surfaceand then gradually begin to return to the atmosphere, which means that the occupants of the house are exposed to indoor pollutants for a long time after the fire.

SEE | The science of indoor air after a wildfire:

To provide guidance to people who need to clean up after a fire, scientists are studying how air cleaners work and how surface cleaning affects air quality.

Based on his findings, Farmer’s cleaning recommendations include:

• Opening the windows as soon as the smoke clears. The sooner you clear the smoke, the better.
• Clean fabrics such as bedding, clothing and curtains that may have retained smoke.
• Vacuum the floor. Wear an N95 mask while doing this because it can create soot or smoke debris.
• Wash the floor with soap and water and wipe down as much as possible, including the walls if your area has a lot of smoke. Clean ceiling fans and other infrequently cleaned surfaces. Change the water when it becomes dirty.
• Clean the ‘secret areas’ of your home such as bedrooms, basements, carpets and mirrors.
• If your HVAC system is working, consider having it professionally cleaned. Change the filters on your home’s HVAC or air purifiers and run fans regularly.
• Remove and wash the furniture quickly. If you still smell smoke, consider a deep cleaning or replacement.