Last night’s fish–or worse, cannabis or wildfire smoke–can persist for many months inside your home

Noxious odors such as third-hand smoke are pretty obvious to the nose, and our noses will tell us that a home smells significantly better if we remove a stinking couch or clean the drapes. However, scientists have found that smoke and other kinds of VOCs tend to permeate hard surfaces, too.  Before today, thin organic films with nanometer thickness were thought to be main surface reservoirs. A new study proves that permeable and porous materials such as painted surfaces, cement and wood are likely the major surface reservoirs in a home. (Indoor surfaces can act as massive sponges for harmful chemicals)

For several years, we’ve written about the many sources of VOCs, such as cooking, spray cleaning, personal care and our hobbies. Additional significant contributors include tobacco smoke, and increasingly, air pollution caused by wildfires.  It turns out that these VOCs can be absorbed into the large surface areas in our homes (even “hard” surfaces) and slowly vaporize back into the air for up to a year, if they’re not removed by physical cleaning.  The health risks come from inhaling compounds when they "off gas" from these surfaces and through dermal uptake when contaminated surfaces are touched.

The implication of this work means that ventilation is not enough to take away VOCs–and that even the cleaning products you use may be emitting VOCs that absorb into surfaces.  Commercial cleaners can be especially persistent, given that they are used to tackle a higher load of microbes in public spaces.  University researchers used a surface-indoor solvent extractor to directly collect films from cleaned surfaces in a controlled lab setting and on regularly washed surfaces in university buildings. While the composition of the films was different, they all contained semi-volatile organic compounds (SVOCs) that can become airborne and impact indoor air quality. (Cleaned surfaces may be germ-free, but they're not bare)

This research further highlights why it’s important to clean hard surfaces regularly, and only use non-toxic spray cleaners.  After all, you don’t want to replace burnt-food or tobacco smoke VOCs with chemical VOCs from your cleaners!  You may not get it all on the first cleaning, but slowly, you can create less “volatile” surface films in your home.  This also highlights the importance of not using plug-in air fresheners and commercially-made candles, which are prolific VOC and PM2.5 producers.  Covering VOCs with more VOCs just doesn’t make sense!  

Backing up our article on cleaning away wildfire smoke, the good news is that basic household cleaning–vacuuming, dusting and mopping with a commercial, nonbleach solution–removed most of the VOCs.  We also still recommend changing your HVAC filter and even increasing filter surface area in order to make it a whole-home air purifier. 

Photo by Towfiqu barbhuiya on Unsplash