Harmful smoke from wildfires lingers in homes long after the initial blaze, reveals new research.
The study shows that wildfire smoke can attach to indoor surfaces – such as carpets, curtains or counters – extending the exposure for people inside and potentially causing health problems even after an initial clean-up by air purifiers.
The research, published in the journal Science Advances, illustrates the “hidden and persistent” health threats many people. are facing given the increase in wildfires over the last decade, say scientists.
Professor Delphine Farmer, of Colorado State University in the US, says the findings also show that simple surface cleanings – such as vacuuming, dusting or mopping – can reduce exposure and limit risk.
Farmer said: “This research shows that events like the Marshall Fire in Colorado, the wildfires in Canada and the recent fires in Hawaii present serious exposure potential – not just when they occur but well after.
“This paper is a key initial step towards providing actionable and practical information on how to protect yourself and clean your home.”
To better understand how smoke enters and then stays in buildings, the research team burned pine wood chips in a net zero energy residential testing facility operated by the National Institute of Standards and Technology (NIST) in Maryland.
The facility is frequently used to study how different systems impact the ways energy, water and air move through a single-family house.
Doctor Dustin Poppendieck, an environmental researcher at NIST who helped coordinate the project, said: “The NIST Net Zero House allowed the researchers to track the movement and transformation of chemicals in the air and onto surfaces in real time using instruments in ways that don’t interfere with the behavior of the smoke.”
The smoke injection sessions occurred regularly over several days.
Farmer said the total amount applied was comparable or slightly under the particulate levels seen during the Canadian wildfires.
The team then took measurements of air quality levels and surface conditions after opening exterior doors and windows, cleaning and use of the home’s built-in air cleaning systems.
Farmer said findings from the research approach could also be applicable to other large air pollution events.
Because there has not been a lot of similar indoor air research, the researchers leaned on previous findings from others around the effects of cigarette smoke to inform their approach.
Farmer said burning nicotine causes specific compounds with well-known health concerns and that the comparison to their project findings was informative.
She said: “Nicotine reacts on surfaces to create a particularly nasty set of compounds called nitrosamines, which is where the real concern from thirdhand smoke that is left behind comes from.
“Whereas with wildfire smoke, we found there was a huge diversity of organic compounds that stick to surfaces, which then slowly bleed off.”
Farmer said the amount, persistence and variety of compounds from the wildfire smoke in each case could potentially change the recommended approaches for cleaning the indoor spaces.
She says it is an area of research the team hopes to explore in the future.
For now, she said the research was able to show that the amount of smoke left on surfaces was proportional to the surface area that was cleaned.
That means simple cleaning and specifically addressing large but little-noticed spaces that may trap harmful compounds such as cabinets and HVAC systems could be beneficial right away.
Farmer said: “As we continue this research, we would like to know just how effective different cleaning approaches are and when residents should move from relatively simple steps like using commercial cleaning supplies for mopping to more drastic steps like replacing the drywall altogether.”
Her team is now looking at how smog may enter and remain in the home in much the same way as wildfire smoke.
She added: “In the future, I want to explore how the economics of making a more energy-efficient building play into these questions and help people understand the risks and potential solutions available to them.”
Produced in association with SWNS Talker
