We all know to wash our clothes after sitting at a campfire to get rid of that clinging smell of smoke. But cleaning our homes after wildfire smoke has moved through the area isn鈥檛 as commonly taught鈥攁nd according to a new study, it鈥檚 a necessary habit to keep harmful chemicals from hanging around.
New research has found that wildfire smoke can leave compounds called polycyclic aromatic hydrocarbons (PAHs), which are highly toxic, on surfaces inside a home after an area has been exposed to wildfire smoke.
鈥淭hey are associated with a wide variety of long-term adverse health consequences like cancer, potential complications in pregnancy and lung disease,鈥� Elliott Gall, associate professor in Mechanical and Materials Engineering at Portland State and lead author of the research, said in a Tuesday . 鈥淪o if these compounds are depositing or sticking onto surfaces, there are different routes of exposure people should be aware of.鈥�
While there鈥檚 consistent public messaging about closing your windows and using air purifiers to lower your risk of exposure during periods of heavy wildfire smoke, many people aren鈥檛 aware that there can still be risks post-wildfire.
PAHs are formed by the combustion process at high temperatures, and can be seriously carcinogenic. This new study, which has been accepted for publication in the journal Environmental Science & Technology, set out to assess the kinds of risks that PAHs accumulating in our home might cause after the end of a wildfire.
Researchers looked at the amount and persistence of these chemicals on three common surfaces in the home: glass, cotton and mechanical air filters. After exposing these surfaces to a wildfire smoke proxy, they allowed them to age indoors over around four months to see how long the PAHs would stick around.
What they found was that levels of PAHs on these surfaces were elevated for weeks after the initial smoke exposure.
The chemicals clung the most stubbornly to air filters, with levels only reduced by 74 per cent after 37 days. In the same time period, PAH levels went down 81 per cent on cotton and 88 per cent on glass.
While this shows that there is a significant reduction in these chemicals on surfaces over time, and that they don鈥檛 persist indefinitely, there鈥檚 still a substantial amount of time in which these chemicals are present in homes, according to this study.
The solution is fairly simple, according to researchers. Washing cotton materials just once after a smoke event reduced the PAHs by 80 per cent in one fell swoop, and using glass cleaner on windows and other glass surfaces provided a 60-70 per cent reduction in PAHs. However, air filters need to be replaced after an extreme smoke event, researchers said, as they can鈥檛 be cleaned.
鈥淓ven if there鈥檚 potentially some more life in them, over time PAHs can partition off the filter and be emitted back into your space,鈥� Gall said. 鈥淲hile it may be a slow process, our study shows partitioning of PAHs from filters and other materials loaded with smoke may result in concentrations of concern in air.鈥�
Depending on how you interact with contaminated materials in the wake of wildfire smoke, your risk of ingesting chemicals could be higher or lower. For instance, a drinking glass which was exposed to wildfire smoke could present a serious risk if held and drunk from without being cleaned first.
The study still leaves unanswered questions in terms of what other materials in the home may have PAHs on them after wildfire smoke moves through an area, but researchers say this study provides a first step in understanding how to minimize your risk of toxic exposure.
Simple household cleaners can significantly lower your exposure risk, researchers found. Future studies are hoping to build on this work to identify what other surfaces may accumulate PAHs and what the potential health impacts from this could be.
