Discover and read the best of Twitter Threads about #AAAR2022
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Some exciting news. A few weeks ago (October 4) my twins presented their first research poster at the American Association of Aerosol Research (#AAAR2022) annual conference in Raleigh, North Carolina!! (1/5) 
It was considered as “independent study” by their school principal so it counts as going to school. (2/5) aaarabstracts.com/2022/view_abst…
Eben's air-airport cartoons #AAAR2022 out!
Incomplete combustion here, there & everywhere.
Air-lock (not)
Important article by @PatriciaFabianS & @jonlevyBU: investment in improving school air quality is critical.
Adds to reminder by @IAQinGWN at #AAAR2022 yesterday that investing in filtration can realize $10-100 return per $ spent e.g. via ⬇️ absences.
theconversation.com/investing-in-i…
Adds to reminder by @IAQinGWN at #AAAR2022 yesterday that investing in filtration can realize $10-100 return per $ spent e.g. via ⬇️ absences.
theconversation.com/investing-in-i…
Well-maintained HVAC filters or portable air cleaners can “also clean the air of pollen particles, mold spores & pollution from car exhaust and industrial operations. And in areas where wildfires are common, filters reduce the concentration of smoke particles inside buildings.”
[In schools that increase ventilation rate] “For kids and school staff, particularly those with asthma, allergies and sensitivities, this can mean fewer missed days of school, less medication, and fewer asthma attacks and subsequent trips to the hospital.”
onlinelibrary.wiley.com/doi/10.1111/in…
onlinelibrary.wiley.com/doi/10.1111/in…
Q: What is the one thing we still need to know about infectious transmission?
Ans: We talked about this a little bit already.. it would be really really nice to collect a virus and say yes/no on infectious without a lab.
Most of my stuff is PCR analysis. How do you know if it's infectious?
Avoid the culture.
Most of my stuff is PCR analysis. How do you know if it's infectious?
Avoid the culture.
#AAAR2022 Panel 1 - Lesson Learned from the COVID- 19 Pandemic and Panel 2 - Gaps in the Aerosol Science Identified During the COVID-19 Pandemic
1. Lessons
2. Gaps
Here we go! Hope I can learn some stuff.. 1/
1. Lessons
2. Gaps
Here we go! Hope I can learn some stuff.. 1/
Provide opportunity to have discussion. Recording video and audio to hopefully later -
@huffman just gave me permission to live tweet all this. Phew.
@PollittKrystal is tag-teaming on moderation.
@huffman just gave me permission to live tweet all this. Phew.
@PollittKrystal is tag-teaming on moderation.
Key thing you learned -
- Expect the unexpected. In beginning we focused on healthcare facilities.. fitness centers.. restuarants - realized homes bc of poor ventilation were highest problem areas for virus aerosols.
Expect what you don't expect
- Expect the unexpected. In beginning we focused on healthcare facilities.. fitness centers.. restuarants - realized homes bc of poor ventilation were highest problem areas for virus aerosols.
Expect what you don't expect
#AAAR2022 Improvement of Air Quality in Vehicles – Simulation of Two Different Use Cases of HEPA Filtration. Matisse Lesage, David Chalet, Jérôme Migaud, Christoph Krautner, SHIKHAR ARORA, Nilesh Tharval, Martin Lehmann, MANN+HUMMEL GmbH
Ultrafine particles matter a lot. In number. 90% of the number conc. 10% of the mass (they are not heavy). But they follow gas streamlines into your body - direct route to the deepest, dearest parts of your body. You don't want this. Lots of unknowns how terrible this..
UFPs can be solved w. improved filtration in the car cabin. Cabin air filters. We manufacturer filters. Bunch of fancy filters.
#AAAR2022 Aerosol Dispersion of Submicrometer Particles in an Aircraft Cabin. Stephanie Vannarath, Peter Kim, Mitchell Ford, Arvind Santhanakrishnan, Yu Feng, CHANGJIE CAI, The University of Oklahoma Health Sciences Center
Airplane cabins! Oh boy.. excited for this one.
infectious aerosols exist. Particularly interested in submicron ones - deep in our respir. tract. Travel further. Remain airborne longer. For the same mass, they have higher surface area.
Settling times of different particles 1 um. They can be suspended in the air for 9h.
Settling times of different particles 1 um. They can be suspended in the air for 9h.
#AAAR2022 Suppressing Spread of Viral Sneeze Droplets Using Transparent Curtains in Large Food Processing Facilities. SUNIL KUMAR, Maria King, David Klassen, Texas A&M University
Modeling rooms with and without partitions
Many studies show HVAC matters (a lot) in reducing spread of virus.
#AAAR2022 Spray Droplet Size in Liquid Sheets Containing Surfactants and Oil Emulsions. IAROSLAV MAKHNENKO, Long Nguyen, Cari Dutcher, Christopher J. Hogan, Elizabeth Alonzi, Christine Colby, Steven Fredericks, University of Minnesota
Agricultural spraying - spraying drift is a problem. 30% of all complaints come from this phenom. Droplets are traveling long distances airborne.
100-150 micron droplets.
Need to prevent spray drift: Trees around your field.
100-150 micron droplets.
Need to prevent spray drift: Trees around your field.
droplet size distribution - controls -
Chemical composition and Nozzle type
Chemical composition and Nozzle type
#AAAR2022 Cleaning the Indoor Air with Low-Cost DIY Air Cleaners. Nirmala Thomas Myers, Taewon Han, Kevin Dillon, GEDIMINAS MAINELIS, Rutgers, The State University of New Jersey
#CorsiRosenthalBox talk
#CorsiRosenthalBox talk
CR/DIY Filtration -
Measured dB, fan temp, power consump. (kWh), air velocity, particle concentraitons
Purchased a bunch of Lasko fans
Bunch of filters MERV 8-13 1-4" thick.
Measured dB, fan temp, power consump. (kWh), air velocity, particle concentraitons
Purchased a bunch of Lasko fans
Bunch of filters MERV 8-13 1-4" thick.
Made single panel versions
2-filter version (triangle)
CR 4-filter version
2-filter version (triangle)
CR 4-filter version
#AAAR2022. Plenary: @IAQinGWN
- A story about filters....
- How to improve indoor air cleaner
1- Keep it dry
2- Source control
3- Ventilation
4- Air cleaning
- Filtration (air cleaning) has the shortest history. Only 50-100 years use in buildings.
1/
- A story about filters....
- How to improve indoor air cleaner
1- Keep it dry
2- Source control
3- Ventilation
4- Air cleaning
- Filtration (air cleaning) has the shortest history. Only 50-100 years use in buildings.
1/
- ASHRAE standard 52.2 for filtration is only 23 years old.
- Measured CO2 and PM2.5 decay in a classroom that was supposed to be operated at 6 air changes per hour with ventilation and filtration. But it was actually at ~2 air change per hour.
2/
- Measured CO2 and PM2.5 decay in a classroom that was supposed to be operated at 6 air changes per hour with ventilation and filtration. But it was actually at ~2 air change per hour.
2/
- Why does filtration fail to meet goals?
- Issue #1. Air has to get to the filter. For central heating homes the recirculating rate can range from 2-8 when the fan is on. BUT the fan can often only 20% of the time, with HUGE variation on the run time.
3/
- Issue #1. Air has to get to the filter. For central heating homes the recirculating rate can range from 2-8 when the fan is on. BUT the fan can often only 20% of the time, with HUGE variation on the run time.
3/
#AAAR2022, @IAQinGWN.
- Lots of reasons filtration is not optimal.
> energy cost
> too noisy
> filtration replacement cost
1/
- Lots of reasons filtration is not optimal.
> energy cost
> too noisy
> filtration replacement cost
1/
- Trade offs between performance and runtime.
- Can they improve on the concentration threshold approach for running the portable filter?
-Unlikely to be universal threshold due to sensor and environment variability.
2/
- Can they improve on the concentration threshold approach for running the portable filter?
-Unlikely to be universal threshold due to sensor and environment variability.
2/
- Made some modeled data sets of source and removal rates.
- The threshold value changes based on the sources in each apartment.
/3
- The threshold value changes based on the sources in each apartment.
/3
#AAAR2022 Characterizing and Comparing Respiratory Aerosol Emission for Pre-adolescent, Adolescent, and Adults during Sustained Phonation. MAHENDER SINGH RAWAT et al. Clarkson University
Respiratory aerosol emissions.. size distribution matters, virality matters.
Motivation - respiratory aerosols well reported for adults - but less for kids / young adults
#AAAR2022 Say It Don't Spray It! Large Droplet Emissions from Speaking, Singing, and Playing Wind Instruments. KY TANNER, Kristen Good, Dan Goble, Nicholas Good, Amy Keisling, Christian L'Orange, Emily Morton, Rebecca Phillips, John Volckens, Colorado State University
Large salivary particle emissions! Yay. Yuck.
Focusing on these large particles.. part of a larger study that looked at the full size range of emissions. Depicted in grey. Everything in this talk is above 35 um.
#AAAR2022 Absolute Respiratory Particle Number and Mass Exhalation Rates and Size Distributions during Breathing and Vocalizing. JONATHAN P. REID et al., University of Bristol
begin - team is huge / lots of help / team effort -
150 human participant
#AAAR2022. @SarahRHaines
- Indoor dust can be resuspended by human activity. Dust can be use as a tracer to determine the presence/absence of RNA (i.e. SARS-COV2).
1/
- Indoor dust can be resuspended by human activity. Dust can be use as a tracer to determine the presence/absence of RNA (i.e. SARS-COV2).
1/
- Deployed indoor air cleaners in homes/classroom where people who COVID positive.
- In home cleaners placed in isolation room, outside and in the main living area. After 1-2 weeks dust was removed from filters => extracted => qPCR analysis.
2/
- In home cleaners placed in isolation room, outside and in the main living area. After 1-2 weeks dust was removed from filters => extracted => qPCR analysis.
2/
- Cool mist humidifiers were often used in homes/isolation rooms which greater decrease the flow rates of the air cleaners.
- Isolation rooms in homes had higher copy numbers.
- SARS-COV2 was detected in 2/7 deployed filters in classrooms/lunchrooms.
/3
- Isolation rooms in homes had higher copy numbers.
- SARS-COV2 was detected in 2/7 deployed filters in classrooms/lunchrooms.
/3
#AAAR2022. @LioraMael
- How do homes recover when impacted from wildfires.
- @LioraMael notes that her home burned down in the Marshall fire the day before she was to move in. #RealworldImpacts
1/
- How do homes recover when impacted from wildfires.
- @LioraMael notes that her home burned down in the Marshall fire the day before she was to move in. #RealworldImpacts
1/
- Looked particulate matter in a house on the edge of the Marshall fire roughly one month after the fire.
- Cleaning activities increased the particle concentrations in the home.
2/
- Cleaning activities increased the particle concentrations in the home.
2/
- Particle concentrations below 500 nm increased both with cleaning activity AND when no one was in the house.
- 500 nm and below particle burst coincide with the HVAC cycles. Cause unknown.
3/
- 500 nm and below particle burst coincide with the HVAC cycles. Cause unknown.
3/
#AAAR2022. Xiaochen Tang.
- Does long term exposure of Tobacco Specific Nitrosamines (TSNAs) lead to negative health impacts.
- Previous research shows TSNAs stick to surfaces. TSNAs hard to measure due to reactivity (esp NNN, NNK).
1/
- Does long term exposure of Tobacco Specific Nitrosamines (TSNAs) lead to negative health impacts.
- Previous research shows TSNAs stick to surfaces. TSNAs hard to measure due to reactivity (esp NNN, NNK).
1/
- Added HONO enriched air to chamber with cloth coated with nicotine to create TSNA. Examined cellulose and cotton with/without sweat and skin oil.
2/
2/
- HONO deposition increase with nicotine addition.
HONO deposition may have been inhibited by water presence in cotton materials.
-TSNA increased in production in present of sweat and skin oil.
3/
HONO deposition may have been inhibited by water presence in cotton materials.
-TSNA increased in production in present of sweat and skin oil.
3/
#AAAR2022. @ProfPeteD. ALPACA Project Overview
- ALPACA - Investigation in artic air quality in urban artic environments.
- When it is -14F(?C) people are inside. But in Fairbanks there is a high prevalence of wood burning stoves.
1/
- ALPACA - Investigation in artic air quality in urban artic environments.
- When it is -14F(?C) people are inside. But in Fairbanks there is a high prevalence of wood burning stoves.
1/
- What happens when you move polluted air from outdoors indoors with a 50 C temperature difference?
- In general outdoor PM10 concentrations higher outdoors than indoors, EXCEPT when pellet stove was used inside the house. 2/
- In general outdoor PM10 concentrations higher outdoors than indoors, EXCEPT when pellet stove was used inside the house. 2/
- Furfural and furan, gases from wood combustion, had similar concentration indoors and outdoors. But outdoors had more variability.
- Cold outdoors most SVOCs are in the particle phase. Warm indoors the chemicals move into the gas phase.
3/
- Cold outdoors most SVOCs are in the particle phase. Warm indoors the chemicals move into the gas phase.
3/
#AAAR2022. @etgall
- Can you use consumer grade sensors be used to estimate particle infiltration.
- Survey asking what mitigation method they used during wildfires: main response stay indoors and keep windows and doors shut.
1/
- Can you use consumer grade sensors be used to estimate particle infiltration.
- Survey asking what mitigation method they used during wildfires: main response stay indoors and keep windows and doors shut.
1/
- Corrected Purple Air sensor measurements to reference station.
- Outdoor PM2.5 concentrations varied by over a factor of 2 outdoors over 25 km during wildfire.
- Indoor concentrations varied from equal to outdoor data to order of magnitude lower than outdoor.
2/
- Outdoor PM2.5 concentrations varied by over a factor of 2 outdoors over 25 km during wildfire.
- Indoor concentrations varied from equal to outdoor data to order of magnitude lower than outdoor.
2/
- If you assume indoor sources are ignored, then you can use a mass balance to determine the infiltration factor.
- Assumption is better during night time (less human activity).
3/
- Assumption is better during night time (less human activity).
3/
#AAAR2022. Pradeep Prathibha. USEPA
- Do DYI filters help during wildfire events?
- For this study looked a 1 filter taped to a fan (not 4 filters and fan of #CorsiRosenthalBox) 1/
- Do DYI filters help during wildfire events?
- For this study looked a 1 filter taped to a fan (not 4 filters and fan of #CorsiRosenthalBox) 1/
- Looked a Hoopa tribe spring/fall interventions in Northern CA at 8 homes.
- Compared two weeks of no air cleaner/DYI/commercial air cleaners. 2/
- Compared two weeks of no air cleaner/DYI/commercial air cleaners. 2/
- DYI air cleaner worked just as well if not better than commercial air cleaner during study from IAQ perspective.
- Most homes had commercial filters, but not used prior to study due to cost of filter replacement.
3/
- Most homes had commercial filters, but not used prior to study due to cost of filter replacement.
3/
#AAAR2022. @EarthMechanic
- What happens on surfaces when wildfire smoke comes indoors?
- Indoor surface films are complicated, diverse, chemical mixtures, patchy and remain for periods longer than the air change rate (weeks/months).
1/
- What happens on surfaces when wildfire smoke comes indoors?
- Indoor surface films are complicated, diverse, chemical mixtures, patchy and remain for periods longer than the air change rate (weeks/months).
1/
- Gas surface reactions can happen. But so can reactions WITHIN the condensed phase film.
- You can find third hand smoke tracers in houses of people who don't smoke.
2/
- You can find third hand smoke tracers in houses of people who don't smoke.
2/
- In third hand smoke, a bunch of chemicals on surface go down in concentration over time. Some chemicals that should be reactive with ozone don't change in concentration when on surfaces.
3/
3/
#AAAR2022. @kjmayer4. (disclosure: I was involved in this study)
- Cited study showing in 2020 over 25 million Americans (8%) experienced >100 ug/m3 of PM2.5.
- #CASAChem Experiments looked at the impact of long range smoke impacts.
1/
- Cited study showing in 2020 over 25 million Americans (8%) experienced >100 ug/m3 of PM2.5.
- #CASAChem Experiments looked at the impact of long range smoke impacts.
1/
- Examined 1) fresh smoke, 2) fresh smoke plus ozone, 3) aged smoke.
- Ozone addition to fresh smoke did not change the particle composition or sized distribution significantly indoors.
2/
- Ozone addition to fresh smoke did not change the particle composition or sized distribution significantly indoors.
2/
- Aged smoke was smoke that sat in chamber for a couple hours prior to injection into the house.
- Ozone in addition to aged smoke shows change in particle chemical concentrations over time.
3/
- Ozone in addition to aged smoke shows change in particle chemical concentrations over time.
3/
#AAAR2022. @ChemDelphine discusses #CASAChem study (full disclosure I was involved).
- CASA was a huge collaborative research group project to investigate indoor chemistry experiments related to wild fires, ozone, and surface aging. 1/
- CASA was a huge collaborative research group project to investigate indoor chemistry experiments related to wild fires, ozone, and surface aging. 1/
- "Clean air act has really worked." With respect to sulfate.
- But wildfire smoke is still a big driver. 2/
- But wildfire smoke is still a big driver. 2/
- Simulated wood smoke infiltrating home by using a cocktail smoker and ponderosa pine.
- Gas Phase biomass burning markers never returned to backgrounds even after days of ventilation.
Surface/air partitioning controls long term partitioning. 3/
- Gas Phase biomass burning markers never returned to backgrounds even after days of ventilation.
Surface/air partitioning controls long term partitioning. 3/
