Thread by @CorsIAQ

1/ As a follow-up to my earlier email ....
First, the concentrations of ozone needed to disinfect indoor surfaces is significant and approach or exceed the IDLH (Immediately Dangerous to Life or Health) level. So, use of ozone should be done w/ great care, if done at all.

https://twitter.com/CorsIAQ/status/1434278672983203841

2/ Ozone (O3) is a moderate oxidant. It reacts with almost all indoor materials, some more than others, as well as oils that we add to or unknowingly leave behind (e.g., skin oils) on those surfaces.

3/ These reactions can (over time), lead to material degradation, e.g., brittleness of rubber seals, leaching of lead from lead-based paints, and even increased susceptibility of some materials to mold growth (research done in collaboration w/ @KerryKinney14 @ut_caee ).

4/ I once did work for a musician in Detroit that had his home heavily ozonated. In the process he had works of art, seals on toilets and water heaters destroyed and more.

5/ Ozone reactions with indoor materials ALWAYS lead to some amount of oxygenated by-products that may be irritating to the respiratory system, or worse.

6/ Some ozone reaction products have a high vapor pressure and will not persist long indoors. Others have low vapor pressure and can persist for days to weeks.

7/ I once did work for an elderly couple that had purchased an apartment in a senior living facility. The previous tenant died in the apartment and the apartment was ozonated afterward. One of the new tenants had respiratory issues after moving in.

8/ when I visited, as soon as the door opened I smelled the lingering odors of a bad mixture of carboxylic acids commonly formed when ozone reacts with indoor materials. The apartment had been ozonated weeks before and the odors persisted.

9/ Ozone also reacts with unsaturated organic compounds, e.g., terpenes emitted from wood, many green cleaning products, air fresheners, and body sprays and perfumes. This leads to formation of reaction products w/ a wide range of vapor pressures.

10/ Some of these by-products, e.g., acetaldehyde, have relatively high vapor pressures and will not persist indoors. Others have low vapor pressure and can adsorb to indoor surfaces or form secondary organic aerosols that deposit on those surfaces, leading to persistence.

11/ I have done a lot of research on indoor ozone reactions, including at elevated concentrations used for building disinfection (w/ a young @Poppendieck)
researchgate.net/publication/24…

sciencedirect.com/science/articl…

12/ Other graduate students I have worked with have also done excellent work on ozone reactions, reaction products, and control strategies, including @etgall, @LoseurPoseur, @clementcros, @joshaldred, Heidi Hubbard, Chi Hoang, Donna Kunkel, Golam Sarwar, and others.

13/ @CJWeschler was a trailblazer & remains the authoritative figure on this topic. @gcmorr has also done excellent work on ozone reactions w/ indoor materials. Ray Wells & colleagues @NIOSH have led efforts to characterize reaction products & potential health effects.

14/ The point is that a lot is known about ozone chemistry in buildings. Exposing indoor materials to elevated concentrations of ozone leads to unwanted and unintended consequences.

15/ There is little evidence to suggest fomites are nearly as important as airborne virus-laden aerosol particles. Schools should prioritize resources for the latter over the former. Turning classrooms into chemical reactors is not the right solution.

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