Thread by @jljcolorado

1/ The State of Ventilation in the US as illustrated by a trip to the #AAAR2022 conference.

Just boarded @RideRTD bus to @DENAirport. 1/3 full, so far I am the only one with a mask (N95 Aura).

CO2 already quite high 5 min. after boarding even tho NOT full: poor ventilation...

2/ Still on @RideRTD bus to @DENAirport.

CO2 steadily climbing. Now over 2600 ppm, meaning >5% of the air we are breathing is "second hand", it has been in someone else's lungs before.

POOR ventilation. ~10 ppl masked our of 45, mostly KN95, few N95, 1 surgical.

#CovidCO2

3/ Made it to @DENAirport. Eating something outdoors so that I can remove the mask as little as possible in the terminal and the plane.

The CO2 sensor is measuring typical outdoor levels.

#CovidCO2

4/ At @DENAirport Main Terminal, by the security checkpoint.

Lots of ppl, 10% masked, mostly KN95.

Ventilation ok, though probably not good enough If we are going to rely on translation is the only layer of protection.

Hopefully there is some filtering.

#CovidCO2

5/ Train at @DENAirport from Main Terminal to Departure Terminal.

Crowded, very short ride... And poorly ventilated.

#CovidCO2

6/ Bathroom at @DENAirport. As I saw in a previous trip it is very poorly ventilated. No wonder it stinks in here!

@DENAirport, you need to do better on bathroom ventilation!

#CovidCO2

7/ Boarding @united. I was lucky to board early: CO2 was low, 700 ppm

Quickly going up. Little ventilation flow, so little filtering

Annoyingly @united personnel offered only a disinfecting towel when boarding... for a virus that transmits poorly, if at all, through surfaces!

8/ @united announcement: "Safety is our top priority"... as unmasked flight attendants perform safety demonstrations and CO2 stays high...

Ah, the irony!

#CovidCO2

9/ I do choose to fly @united, when I have to fly. NOT bc they are GOOD on safety on airborne diseases. But they are the LEAST BAD of the options available to me. @SouthwestAir seems to be much worse, per CO2 measurements that people have posted. Or e.g.:

https://twitter.com/roseAtmos/status/1576718589201383425?s=20&t=5lLsxcqZMCCAQWkpZh5adw

10/ I regularly encounter some ppl, especially in the US, who have never heard of CO2 as a tracer of ventilation, and about its use as a surrogate of airborne disease transmission potential.

This article and thread give some bakground:

https://twitter.com/jljcolorado/status/1376667218960920578

11/ I have chosen to go to #AAAR2022 (Annual Conference of @AmericanAerosol) in part bc I expect it to be pretty safe: masks are required everywhere indoors, and vaccination is also required.

12/ Not surprising: we understand airborne transmission

Unlike conferences from fields that mostly DO NOT understand airborne transmission (e.g. American @PublicHealth Assoc., some medical conferences) where masks are not required... & often turn into superspreading events

13/ Although I am glad to see that @IDWeek2022, an upcoming major infectious disease conference, does require well-fitting masks and vaccination too. Maybe we are getting through, if slowly.

idweek.zendesk.com/hc/en-us/artic…

14/ But unfortunately this is indeed still pretty common:

https://twitter.com/edsuom/status/1576737777534009344

15/ During the @united flight CO2 stayed around 1100-1400 ppm. Not great, but not terrible given the HEPA filtering (which should be on when plane is on the air -- unlike being OFF when we boarded). And less bad than other airlines.

16/ Arrived to @sheratonhotels

Unfortunately CO2 in room is elevated. Either air recirculation thru filter (if I am lucky), or infiltration from other rooms (if less lucky), like studies where ppl got COVID from ppl their never met in quarantine hotels:

wwwnc.cdc.gov/eid/article/28…

17/ Day 1 of the #AAAR2022 (American Association for Aerosol Research @AmericanAerosol) Conference.

Picking up lunch at @jimmyjohns in Raleigh, NC (to eat outdoors).

Quite a few ppl, good ventilation.

18/ At the @AerodyneRes Mini Users Meeting at the #AAAR2022 conference.

40 ppl at Raleigh Convention Center @Raleigh_CC. Large room, high ceiling, ventilation is on.

CO2 staying low.

EVERYONE is masked (required), 1/2 KN95, 40% N95, 10% other (surgical and cloth). [Quite safe]

19/ Just arrived into my room ar @sheratonhotels after being away all day. Same as yesterday, CO2 is elevated, indicating some recirculation.

20/ Plenary Lecture at #AAAR2002 at @Raleigh_CC.

500 ppl in large room, good ventilation (~700 ppm CO2)

Everyone masked and vaccinated, so feeling quite safe. Much more welcoming for ppl at higher risk to be able to attend in person.

#CovidCO2