Joshua C. Agar Profile picture
Asst. Prof. | UPD | Wind Engineer | RCE | MSCE | jcagar@up.edu.ph | IAQ Fellow - UP BRS | https://t.co/36DzQIrnnn | https://t.co/UsrKOnr4wL
Dec 21, 2023 7 tweets 3 min read
Our study that developed CO2 monitors that informed occupants of the relative risk that they may be subjected to due to airborne diseases transmitted through shared room air transmission has been published. #CovidIsAirborne

doi.org/10.3389/fbuil.…
Image Using a multivariate method, the ventilation rates of different indoor spaces are determined and used for the subsequent computations using the Wells–Riley model to derive the respective infection risk, particularly of COVID-19. Image
Dec 12, 2023 4 tweets 2 min read
Part of the PowerPoint presentation to be presented on Thursday:

How aerosols move Image Conservation of Mass
Image
Image
Apr 23, 2023 7 tweets 2 min read
High humidity also attributes to high infection rates and deaths due to Covid-19.

Shown below are the trends derived from the correlation between Covid-19 deaths and relative humidity. 60% RH is the Goldilocks Zone: lesser or greater than that results in the increase of the risk Image

Why 60%?

It has to do with two things: (1) lessening evaporation rates due to inhomogeneous mixing and (2) rate of condensation which attributes to the increase of pore pressure within the mask.royalsocietypublishing.org/doi/10.1098/rs…
Feb 5, 2023 7 tweets 5 min read
When used in physical settings, the Cochrane method and RCTs are mere pretentious eminence-based assertions masquerading as empiricism (A thread).

It is important to note that the interventions mentioned are physical in nature, not clinical and medicinal. (1/n) We have two studies that use the Cochrane method:

The first one is the study headed by Derek Chu (funded by WHO) in 2020, which has determined, using the Newcastle Ottawa Scale & Cochrane method, the effectiveness of face masks in stopping transmission. (2/n)
Nov 3, 2022 4 tweets 3 min read
Testing the filtration efficiency (how much they reduce Covid-19 risk) of mask. #COVIDisAirborne

KN95 Mask Copper/Cloth Mask
Nov 1, 2022 5 tweets 2 min read
With no regard to the limits on occupancy and social distancing, here are the reproduction numbers from scenarios where a symptomatic infector within a 40-student DepEd classroom, even though the 1000-ppm CO2 ventilation requirement was satisfied. #COVIDisAirborne Image With no regard to the limits on occupancy and social distancing, here are the reproduction numbers from scenarios where an asymptomatic infector within a 40-student DepEd classroom, even though the 1000-ppm CO2 ventilation requirement was satisfied. #COVIDisAirborne Image
Aug 17, 2022 7 tweets 3 min read
Safe Schools Calculator - Ensuring that the F2F classes will be conducted safely (a thread)

You can download the tool using this link:
github.com/jcagar/SafeSch…

Part 1 - Input Parameters
In the sheet, you'll be plugging in the dimension of the room, the setting (urban or rural). Part 2 - Epidemiology, Additional Filtration, and Outputs

You can also plug in the number of possible positive cases. You can also provide the additional filtration installed.

The calculator will return the risk of infection and the reproduction number.
Aug 5, 2022 12 tweets 4 min read
Movie Theaters - Covid-19 Risk Infection (a thread)

I won't be posting photos for I don't want to use this as petty "hot takes" but rather I intend to use this as a reminder to wear properly-fitted mask and to wear them properly during the film showing. #COVIDisAirborne I literally checked the HVAC from above to verify some of the parameters. Unless the movie theaters will detail their improvements on the ventilation system, I'll simply assume that nothing was done to improve it.
Jul 20, 2022 5 tweets 2 min read
A bit of a warning on face shields is exacerbating the risk of infection. #COVIDisAirborne

Face shields attributed to the Pontresina Superspreader event in July 2020. Not only that face shields are useless, they increase the risk due to what's called street canyon vortex effect. Medical practitioners, who obviously took medicine to dodge math-intensive and physics-intensive topic, attempt to define physical phenomenon but RCTs and meta-analyses, when in fact physics can readily explain how face shields work.
Jul 19, 2022 6 tweets 2 min read
Covid-19 Risk in Public Transportation

Airconditioned buses also pose a higher risk for commuters, to address that, here are the recommended administrative measures:

* Increase the number of buses to reduce headway, decrease travel time, and reduce the # of passengers each bus. *don't allow the symptomatic in.
*disallow speaking loudly within the bus to decrease the degree of vocalization to lessen viral shedding.
Jul 18, 2022 6 tweets 2 min read
How occupancy will affect the risk of infection despite ventilation (a thread) #COVIDisAirborne

Given a constant volume of room, occupancy affects the following:

1. Optimum social distance
2. Rate of emissions of CO2 which will determine the ACH needed to ensure <1000 ppm CO2 Social distance will mainly determine the degree of exposure to the risk caused by sporadic emissions from symptomatic cases and the close-proximity asymptomatic transmissions.
Jul 18, 2022 5 tweets 2 min read
The risk of infection also varies in relation to distance. The social distance is basically inversely related to the occupancy. The more people in the room, the higher risk of infection.
(Note in this graph that the risk of infection increases due to longer durations of exposure) Wearing high-quality and well-fitting masks significantly reduces the risk of infection. However, with poor social distance due to high occupancy, the risk will be still concerning.
(Note in this graph that the no. of infected increases due to longer durations of exposure)
Feb 1, 2022 25 tweets 9 min read
Since @EdselSalvana is deleting his comments in an attempt to gaslight people after being called-out, here is the blow-by-blow sequence of what happened (a thread): It all started with @EdselSalvana sharing this post last Saturday morning:
Jan 30, 2022 7 tweets 2 min read
A bit of a brief explanation about the physics of Covid-19 transmissions (a thread)

#CovidisAirborne #CovidisAirbornePH
(1/7) Image (2/7) Image
Jan 8, 2022 21 tweets 9 min read
Admittedly there's a research gap concerning face shields since they are mainly intended for hospital settings, hence scenarios limited to hospital settings. The general consensus is that face shields are intended for ballistic droplets, not for aerosols.

Below are the studies: Lindsley et al. (2014). Efficacy of Face Shields Against Cough Aerosol Droplets from a Cough Simulator

Face shields are evaluated to stop the initial impact of the cough which brought heavy droplets, however, airborne droplets still make way around.

ncbi.nlm.nih.gov/pmc/articles/P…
Oct 12, 2021 4 tweets 2 min read
And as it turns out, the initiative of exploring the potential for wind power that led to the wind farms in Ilocos Norte...

...came from USAID!

The Marcoses have been consistent of grabbing credit from USAID!

Documentation of the Initiative:
nrel.gov/docs/fy02osti/… The study of compiling the atlas for wind energy in the Philippines started in 1996. The atlas was finished at 2000:

(Lol. They indeed did GEV analysis and interpolated using the projected wind exposure parameters)
Oct 12, 2021 10 tweets 3 min read
Re: Face shields on various scenarios (Another thread)

I was asked, in the spirit of the RCTs, whether I have explored the other scenarios concerning face shields.

Well, yes, I did. The intervention of face shields against sporadic emissions at different angles of attack was simulated and observed, and as it turned out that the ballistic protection only applies for emissions coming from the front. From other angles, risk increases:

Oct 12, 2021 6 tweets 1 min read
Misinformation and falsehoods cascade across three layers:
First is with the perpetrators who spread disorienting misinformation in social media.

Second is with the media on which some are disoriented and pass on the disorientation to the masses.

Third is with the masses. Indeed, the battleground may be dealing with the source. But the ripples of misinformation still trickled down to its main interest and intended audience: the masses.
Oct 11, 2021 31 tweets 9 min read
Debacle of face shields in the Philippines

(A thread)

I see that some of the scientists from other countries are considering recommending face shields to be worn in public.

I beg to differ, presenting how face shields represented the poorest pandemic response in the world. December 11, 2020

The Inter-Agency Task Force (IATF) against Covid-19 of the Philippine Government, through its Resolution no.88, mandated the use of face shields even in public, outside of hospital settings.
pna.gov.ph/articles/11544….
Oct 10, 2021 12 tweets 3 min read
Taytay Chronicles w/ Bayaw Erik
(October 10, 2021) The dreaded face shield
Oct 10, 2021 5 tweets 1 min read
Kindly ask those "lolo" and "lola" giving anecdotes that "attest" the Marcos regime the year-by-year state of affairs during that period. Ask them the specifics, what specifically happened in '72, '77, '81, '83, 84', and '86.

That's how historiography establishes veracity. If they can't provide any to establish the veracity of their narrative, then that points of view that they are presenting, like the other dramatis personae in the past making good light of themselves, will be rebuked, shunned, and reprimanded.