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Jun 15 • 4 tweets • 2 min read
#IndoorAir2022. Arsen Melikov. Plenary. Increasing ventilation rates is expensive, requires energy. Air cleaning also use energy and placement can impact performance. CFD modeling shows variability in ventilation type impacts Infection probability by up to factor of 7. 1/
Personal ventilation is best, supply air as close to breathing activities as possible, e.g. air curtains. Should consider occupant activities when making recommendations. 2/
Source control via ventilation. Clean air at mouth. 3/
"How I was infected during CLIMA 2022 conference..." Nine experts airborne transmission in room for one hour (laughter). (Including @WBahnfleth). Two index patients. "Why did we move the tables, I don't know..." We should still keep distances. 4/

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More from @Poppendieck

Dustin Poppendieck Profile picture
Jun 16
#IndoorAir2022. Toby Carter. How do ozone and hydrogen peroxide interact with surfaces and impact IAQ? Oxidants deposit on surfaces and can release secondary VOCs. Secondary emissions are a function of deposition velocity, reaction yield, oxidant concentration and volume. 1/3
Room relevant material surface to volume ratios are important (very different for offices and bedrooms). Most deposition for ozone was on plastic/paint/skin/soft fabrics. 2/3
Hydroxyl radical concentration vary with time of day and space (highest in kitchen). Concentrations of formaldehyde and decanal increased when modeled people were introduced as a result of hydrogen peroxide and ozone reactions. 3/3
Read 4 tweets
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Jun 16
#IndoorAir2022. @licinadusan. Plenary. Can we feel as good indoors and out? Can our buildings predictively respond to outdoor changes? Can our indoor environments not impact the ecological health of the planet? 1/14
Green certified buildings attempt to achieve these goals. hundreds of certifications globally. Certification schemes started during 1970s energy crisis (BREEAM). Existing certifications focus on building energy, less emphasis on occupants, IEQ and much less on human health.2/14
We consume huge amounts of energy on non-certified buildings and have poor occupant satisfaction (highest complaint is noise). Certification improve, but don't solve occupant satisfaction issues. Improvements still don't reach expected satisfaction of other industries. 3/14
Read 14 tweets
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Jun 15
#IndoorAir2022. Michael Scholand, Piet Jacobs. Is cooking with natural gas a public health risk? "This is like living with a tailpipe in your kitchen". Gas stoves emit NO2, CO, ultrafine particles. 1/
European effort to get data to support EU/UK actions. Emulating @RockyMtnInst study. What happens if you increase hydrogen content of gas to IAQ? "You can't regulate something if you can't measure it." 2/
Phase 2 is a field campaign in winter 22-23 in EU kitchens with gas and electric stoves. What component of IAQ is gas/versus cooking? 3/
Read 4 tweets
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Jun 15
#IndoorAir2022. Plenary Discussions. @CathNoakes, Giorgio Buonanno, Arsen Melikov. Lidia Morawska. Does Monkey Pox have airborne transmission? @CathNoakes "Quite Uncertain" But potential. 1) Before pox show, with fever. Not much data. 2) Lesions. Evidence of mouth lesions.1/6
3) skin flakes could transmit in places like bedding. Potential for airborne transmission (especially from lesions), but may not be a major route. But ventilation and airborne transmission guidelines should be followed in hospitals. 2/6
Lidia: "once it (monkey pox) is in the respiratory fluid there is no limit on what is going to happen." Giorgio: paper on classroom ventilation was important as it communicated to the epi world by using epi language from data engineering studies. 3/6
Read 6 tweets
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Jun 15
#indoorair2022. Giorgio Buonanno. Plenary. In 2020, airborne modeling tools "came out like mushrooms". Most all tools used Wells-Riley and box models and assumed accurate input parameters. 1/4
Quantum = dose of airborne particles required to cause infection in 63% of individuals. Experimental validation demonstrated that volume of particle emission is main contributor to uncertainty. 2/4
Retrospective study in Italy of >10,000 classrooms. Classrooms with ventilation 1.4-10 L/s/person and >10 L/s/p. Risk reduction was 80% in higher ventilated classroom. 3/4
Read 4 tweets
Dustin Poppendieck Profile picture
Jun 15
#indoorair2022. @CathNoakes. Plenary. Breathe is a jet for 30-50 cm, then rises due to temperature, then starts to mix through turbulence. Aerosol production goes up breathe>sing>cough. BUT orders of magnitude differences between people. 1/
Respiratory aerosols are liquids that evaporate over time. Impacts virus viability and aerosol size. Aerosols 20-100 microns get smaller fast and concentrate high concentrations of virus. Variation of size and virus numbers can vary 4-5 orders of magnitude. 2/
Fomites also can have orders of magnitudes of dose. People are not stationary, we move around. But also with wide variability in our rates of interactions with other people. Does/response have orders of magnitudes differences for all aerosol diseases. 3/
Read 5 tweets

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