Wednesday, August 12, 2020

Clean Air Beware


Just when you thought you knew what to do, you don't.


Ventilation is good (and a necessary part of controlling an airborne virus, by the way), but opening windows will not remove the chemicals from most homes, at least according to this work done with the HOME Chem model house.


Our indoor environments are filled with the chemicals that offgas from just about everything that surrounds us, from body care products to scented candles to building materials. Cleaning products are a major culprit here, and also an important consideration while trying to combat a global pandemic via the war against germs, aka chemical disinfectants, aka indoor environmental chemical warfare.


For almost any product you bring into your home, or any activity you perform there, chemicals are released into the air. Not all chemicals are bad, but some of them are. The problem is not even in identifying the "bad" things in the air, but in measuring how much things accumulate, no matter what they are -- everything is bad at the right dose.


Opening the windows is the most straightforward and effective way of reducing these concentrations. The problem is that at some point those windows must be closed. Experiments done in the "chem house" show that the concentrations of typical chemicals found indoors do drop precipitously when we open the windows.


But surprise -- a few minutes after they're closed, the concentrations go right back up to baseline.

The idea is that the chemicals cling to the walls, likely in the macro- and microscopic nooks and crannies on the surface. They act like reservoirs. Volatile organic compounds will offgas into the room, and especially during cleaning activities for example, where they settle onto those surface microtextures, and then re-volatilize into the air continuously.


In conclusion, opening windows is good for flushing chemicals out of the indoor air temporarily, but the real effort must be put into keeping them out in the first place. (Sorry Clorox wipes, I’m looking at you, don't act like you don't offgas.)


Image source: The Broom Maker, Victor on Flickr, 2019


Post Script:

What produces more voc’s, spraying a perfume on your wrist once a day or cleaning your house with a surface disinfectant once a week? *First of all, cleaning and disinfecting are not the same thing, and second of all, you’re probably over-disinfecting.



Opening the window in your home will not flush out the chemicals in the air

Feb 2020,


Chen Wang et al. Surface reservoirs dominate dynamic gas-surface partitioning of many indoor air constituents, Science Advances (2020). DOI: 10.1126/sciadv.aay8973


A good follow up:

Organic compounds in indoor air like to accumulate in paint

May 2020, Indoor Chem Blog


Measurements and modeling of absorptive partitioning of volatile organic compounds to painted surfaces. Algrim, L. B., Pagonis, D., de Gouw, J. A.,  Jimenez, J. L.,  and Ziemann P. J. Indoor Air, 2020. 00; 1-12


Further reading:

HOME Chem - House Observations of Microbial and Environmental Chemistry

University of Colorado and CU Boulder


ISIAQ - International Society of Indoor Air Quality and Climate


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