Thread by @CorsIAQ

1/ Very interesting study on effects of ozone on adolescent depression. The study focused on elevated ozone concentrations outdoors.

https://twitter.com/IAQsusan/status/1506295520146432003

2/ Remember that ozone of outdoor origin penetrates into buildings and reacts with indoor materials & unsaturated organic compounds in indoor air to form a wide range of reaction products, many of which are lacking tox studies.

3/ When ozone is elevated outdoors or when (unfortunately) devices are used that generate ozone indoors, more of these indoor reactions occur.

4/ Note that ozone even reacts with unsaturated compounds, e.g., squalene, in our skin oils - whether still on us, shed into dust as skin flakes, or smeared onto indoor materials. These reactions also lead to by-products that we inhale.

5/ In a recent study of indoor air quality in schools we found that nearly 75% of all ozone consumption (by reactions) in classrooms is due to ozone reactions with human bodies and clothing in the classrooms.

6/ Because of these indoor reactions, ozone concentrations tend to be much lower indoors than outdoors. However, because of human activity patterns of Americans (we are indoor creatures) ....

7/ On average about 50% of our inhalation dose of ozone of outdoor origin occurs while we are indoors. Our dose is even higher if we use devices that emit ozone indoors (a bad idea).

8/ To reduce the inhalation of ozone and its reaction products, ozone can be removed from buildings using activated carbon filters (on air intake or downstream of recirculated air in HVAC systems) or in portable air cleaners.

9/ My former PhD student - Josh Aldred - did a dissertation on the topic of the costs and benefits of using activated carbon filtration for population health. The results were fairly striking for some types of buildings.

10/ Josh's complete dissertation is here:

A paper that summarizes major results is here: tandfonline.com/doi/full/10.10…

11/ We also had a graduate student (Donna Kunkel) who studied the use of activated carbon sleeves on ceiling fan blades and showed a substantial decrease in ozone concentrations in a test house when teh amended ceiling fan was activated. sciencedirect.com/science/articl…

12/ An alternative to activated carbon are passive removal materials that can be used over large areas that decompose ozone w/ minimal reaction product formation. This lowers ozone concentrations but also precludes more reaction products formed via reaction with other materials.

13/ We have found clay-based plasters & paints that contain kaolinite to be very effective at decomposing ozone w/ minimal reaction products formed. One of my ex-PhD students (Erin Darling) did excellent work in this area for her dissertation.

14/ Erin's dissertation can be found here: repositories.lib.utexas.edu/bitstream/hand…

Some additional papers here: sciencedirect.com/science/articl…

sciencedirect.com/science/articl…

pubmed.ncbi.nlm.nih.gov/27859627/

14/ Appropriate unfired clay bricks are also being used to preserve works of art & historical artifacts in Denmark, as clay also removes organic acids and other indoor gases from air.

15/ One of the reasons that I got into the indoor air quality field nearly 3 decades ago is because it held so much promise for innovation to make the places we spend the dominant fraction of our lives healthier.

16/ As I reflect back I see a lot of innovation from many without a substantial base of federal research funding afforded other fields.

17/ As I look forward I see a lot greater interest and potential funding for indoor air quality research. I hope that those new to the field will realize the successes of the past, build on them as opposed to repeat them, and make buildings better environments for all.