Thread by @CorsIAQ

1/ Motivation for caring about indoor air quality

Prior to this pandemic, the average American lived to be 79 yo (lower now). Of those 79 years we spend, on average, 69 years domiciled inside buildings.

2/ An amazing 54 years are spent INSIDE of our homes. Approximately 26 years are spent lying horizontally on a mattress (perhaps breathing in toluene diisocyanate from your pillow).

3/ The sleep microenvironment remains understudied, but proud of our work done @ut_caee (numerous papers published w/ one more in the queue on controlling particles in breathing zone while sleeping).

4/ Six years are spent outdoors in an average American lifetime (most do not believe this, but activity pattern data indicate little deviation across regions of the US). Four years are spent inside cars/transit systems.

5/ So, Americans are INDOOR creatures (as are Canadians, Germans, etc.). The % time we spend in buildings is approximately the same or slightly more than many types of whales spend submerged below the surface of the ocean.

6/ The fact that we spend so much time in buildings means that our exposure to air pollution, even pollution of OUTDOOR origin, is dominated by the air that we breathe indoors. Even pollution of OUTDOOR origin!

7/ The equation on the first tweet in this thread shows the ratio of inhaled pollutant mass indoors to outdoors. The C ratio refers to concentration of pollutant indoors vs. outdoors. The t ratio is time spent indoors vs. outdoors.

8/ The B ratio is respiratory minute volume (volume of air inhaled per minute) indoors vs. outdoors (on average).

9/ Using typical C, t and B ratios from the literature, it is easy to show that for pollutants of outdoor origin the ratio of mass inhaled indoors vs outdoors ranges from approximately 1 to 10 (1 = ozone, which is highly reactive indoors and so has a relatively low C ratio).

10/ For pollutants w/ significant indoor sources, e.g., formaldehyde or various phthalates, the indoor/outdoor mass inhaled ranges from 25 to 100 or more.

11/ Any way you slice it, our lifetime exposure to and uptake of air pollutants is largely D*O*M*I*N*A*T*E*D by the air we breath indoors - from our homes, workplaces, schools, etc.

12/ And as somebody who studies human exposure to air pollution (and how to reduce such exposure) in the built environment, the fact that the indoor environment is so important is why I started studying it 25+ years ago.

13/ The possibility of dramatically reducing population exposure to air pollution of both OUTDOOR & INDOOR origin by paying more attention to construction, operation, and maintenance of buildings & what we bring into them remains extraordinary and (unfortunately) unfulfilled.

14/ That's what got me into the field of indoor air quality, and what continues to keep me interest in it after all of these years. I am excited that so many others are now recognizing the importance of indoro air and environmental quality. Let's all ... Just do it!