1/ I was asked in an interview today about the history of Indoor Air Quality. I surprised the journalist by starting about 1 million years ago with controlled fires brought into caves.
2/ There is evidence of early recognition of the importance of local exhaust, with fires placed below shafts to the outdoors. How many died from carboxyhemoglobin poisoning before recognition of the importance of ventilation?
3/ Perhaps we can ask the same question today but replace carboxyhemoglobin with COVID-19 and fire in caves with SARS-CoV-2 in (pick your favorite crowded and poorly ventilated indoor space).
Perhaps it is time we learn something from Homo erectus.
Just do it!
4/ I also find this history fascinating in terms of early realization of importance of ventilation to reduce exposure to products of incomplete combustion. Think cooking with gas & importance of exhaust fans.
Perhaps it is time we learn something from Homo erectus.
Just Do It!
5/ Anyway, you can imagine that given the starting point it was a lengthy interview. 😉 To be continued.
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2/ The air pollution that we breathe during our lifetime, even pollution of outdoor origin, is dominated by the air we breathe INDOORS.
3/ We can dramatically reduce our exposure to air pollution by reducing emissions from indoor sources, removing pollutants of indoor origin (ventilation & good engineering controls), & designing/operating buildings to reduce outdoor pollution from penetrating indoors.
Highest % of courses with a hands-on component in the entire CSU system.
3rd highest % of students in natural resources and STEM programs in CSU.
CSU’s highest % of STEM grads who go on to earn doctoral degrees, ranking 8th nationally among 660 master’s level institutions.
It's always had a robust Environmental (Resources) Engineering degree program, among the largest and oldest in the US. That program has graduated a large number of highly-qualified engineers who have served the State of California & beyond.
1/ I agree with @Don_Milton. It is important to distinguish between near- and far-field aerosol particles. In the near field (close contact) there is potential for much higher concentration of aerosol particles in the breathing zone of a receptor.
2/ The actual concentration depends on extent of emissions from infector, body positioning of infector and receptor, mixing conditions between infector and receptor (which depends on a number of other factors), and DISTANCE between infector and receptor.
3/ Aerosol particles do not vanish beyond the near field. They exist in the far field and will accumulate until an approximate steady-state is achieved (more on this later) as long as the infector(s) stay in the space.
Sad that we have come to this point. We are here because throughout this mess political leaders, health authorities, and the general public were irresponsible, stubborn, & impatient. Will we learn from this that "fits and starts" is the worst possible policy?
We did not invoke the precautionary principle early on this pandemic, deciding (without any scientific evidence) that only three of four transmission routes were relevant and downplaying transmission by aerosol particles.
Across the board, there was a lack of unified effort to starve this virus of its hosts & manage it. We did not need major investments. What needed to be done was obvious to many scientists from the start, but lacked acceptance by leaders, unified messaging, & public commitment.
1/ Most important thing at the moment is to starve this virus of hosts. Need political leaders, business owners, bldg managers, school officials & public all acting in concert to substantially reduce inhaled dose of virus-laden aerosol particles in indoor near- & far-fields.
2/ We will find ourselves w/ similar challenges again. So, we also need to reflect on all of the things done wrong to get us into this horrific mess, learn from mistakes, and be prepared to do the right things next time.
3/ There have been unconscionable failures of leadership that fueled this mess. But there have also been many other failures, from general public to academia, media to businesses, medical profession to much more.
1/ Reviewing data from past school study in Texas. On average ventilation rates are considerably higher in portable than in permanent classrooms, but with much greater variability.
2/ Portables are much more connected to outdoor environment - greater infiltration and opportunity for natural ventilation (open door/windows).
3/ But interestingly, portables (on average) appear to have higher rebreathed fraction of air (fraction of inhaled air that was exhaled by others in the indoor space) than permanent classrooms due to higher density (occupants per classroom volume).