Thursday, August 3, 2023
Odor Hunter Extraordinaire Cliff the Z Man Zlotnick
Wednesday, November 30, 2022
Living With Friends
An experimental test home was erected in Austin, Texas during the summer of 2018. The house was designed for ordinary use and included bathrooms, a kitchen, gathering and work areas. Overnight stays were prohibited, but 45 study participants, plus visitors, spent time in the house, occupying it for approximately six hours per day for 26 days, during which they performed scripted activities, such as cooking, cleaning and socializing.The house was deep cleaned with a bleach solution. Nonetheless, researchers said traces of molecules associated with humans were still present. After almost of month of human occupation, the house was alive with molecular and microbial abundance and diversity, albeit unevenly distributed.Not surprisingly, the kitchen and toilet were hotspots of molecular and microbial diversity, though numbers fluctuated with surface cleaning and sanitation. "It appears that, even when a subset of chemistry is removed because of the cleaning, it is only temporary and/or partial, as the sum total of cleaning and human activities overall results in an increase in accumulation of richer chemistry," the authors wrote.
- Teachers did not accurately perceive mechanical ventilation sufficiency
- Air quality and temperature are conflated
- Dramatic difference in IAQ perception (but not quality) in summer vs winter
- Occupants misperceive temperature as a proxy for indoor air quality; they think cooler air is better, and confuse warm air with "stuffy, stale" air
- Teachers in classrooms with worse ventilation were more satisfied with classroom temperature
- Occupants don't understand how the systems work, and think incoming cold air in winter is a defect, for example (when in fact it is the system adding fresh air to the mix); they then say the system isn't working, and therefore they must have bad IAQ; they also think the only time the system brings fresh air is when the AC is on, which is the complete opposite of what's happening
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.
Notes:
Opening the window in your home will not flush out the chemicals in the air
Feb 2020, phys.org
https://phys.org/news/2020-02-window-home-flush-chemicals-air.html
Chen Wang et al. Surface reservoirs dominate dynamic gas-surface partitioning of many indoor air constituents, Science Advances (2020). DOI: 10.1126/sciadv.aay8973
http://dx.doi.org/10.1126/sciadv.aay8973
A good follow up:
Organic compounds in indoor air like to accumulate in paint
May 2020, Indoor Chem Blog
https://indoorchem.org/2020/05/paint/
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 doi.org/10.1111/ina.12654
https://doi.org/10.1111/ina.12654
Further reading:
HOME Chem - House Observations of Microbial and Environmental Chemistry
University of Colorado and CU Boulder
https://indoorchem.org/projects/homechem/
ISIAQ - International Society of Indoor Air Quality and Climate



