Impact of community masking on COVID-19

I find legislation that prevents mask mandates or requirements to be extremely irresponsible and abhorrent. These are made without regards to public safety and in contradiction to overwhelming scientific evidence that showed that wearing proper mask is one of the most effective means to reduce the risk of the spread of COVID-19.

I have presented several posts on this blog on the various scientific studies in support of this. Now comes another one that leave no doubt on the effectiveness of masking in reducing the virus transmission. This was very recently published in Science (a very prestigious and difficult journal to publish in, if you don't know this already), and is done across several villages and on a population of more than 300,000 adults in Bangladesh.

We designed our trial to encourage universal mask-wearing at the community level, rather than mask-wearing among only those with symptoms. We encouraged even healthy individuals to wear masks since a substantial share of COVID-19 transmission stems from asymptomatic or pre-symptomatic individuals, and masks may protect healthy wearers by reducing the inhalation of aerosols or droplets.

When you read this paper, keep this in mind. It is one thing to show scientifically of how masks reduces the spread of aerosols from our mouth and nose. This has been shown clearly and without any doubt base on the many publications and studies that I have highlighted so far. But it is another to show that it does have an impact STATISTICALLY when applied to large population. This latter part is more difficult because it involves a lot of variables. It is why this latest study is very important because it is one of the larger sampling of human population involved in masking (or lack thereof) to reduce the spread of the virus.

The sign of a valid idea is that the more you study it, the more convincing it becomes. Pseudosciences lack this kind of progression, where they continue to struggle getting to First base to prove that such-and-such even exists. In the case of the effectiveness of wearing proper mask to reduce COVID-19 transmission, the more we study it, the more the evidence we gather to point this to be valid, that wearing mask has been shown unequivocally to reduce the risk of the virus transmission.

Zz.

Why You Need To Wash Your Hands For 20 Seconds

Finally, the reason why we should wash our hands for a minimum of 20 seconds has a physics explanation.

The research work was published in the Physics of Fluids journal, which so far has been quite an active journal in publishing papers related to the physics of the coronovirus transmission, making them available widely to the public.

Zz.

Getting My COVID Vaccine This Week

Being under 65 years of age, and with no major health issues (knock on wood), I was not eligible to receive the COVID vaccine in my area during the first 2 waves of its distribution.

But suddenly, it was announced by our state that starting Monday (today), higher-education workers will be included in the expanded criteria to receive the next vaccine distribution. So, after scrambling to find an appointment, I will get my first shot of the Pfizer vaccine this coming Friday, and then the second one later in April. All I can say is : PHEW!

There is certainly a push by the school to get things back to almost normal, in the sense that many of the classes are starting to be offered in person or in a blended/hybrid modality. Certainly classes that have a significant laboratory component are the ones that will probably start to be offered in person. I definitely would prefer to have the vaccine before I have to come in to the campus, so getting the vaccine now is a major peace-of-mind aspect of this whole thing.

It is certainly looking more certain that I may have to ditch my Zoom pants on most days and have to start dressing up again when I teach my classes this Fall! 😀😁

Zz.

Tripple-Layer Mask Blocks Secondary Atomization of Cough Droplets

I had already posted several physics papers on the efficacy of masks, even single-layer ones, in reducing the airborne aerosol. Now comes another paper that deals with how cough droplets actually can break up into smaller-sized droplets that may pass through single and double-layered masks, especially when moving at such high speed from a cough.

It turns out that having a mask with 3 layers or more might be the most effective here (I wonder at how many layers will we will of suffocation? :)) The new research is to be published in Science, and you can get the paper at the link to read to your heart's content.

A review of this paper can be found here. It is fascinating to read that expertise in the study of jet engines are being leveraged in studying the dynamics of this problem. But do you think people who don't believe in wearing masks to reduce the virus transmission will buy any of this? They believe in smartphones and jet engines, don't they?

Z.

Mask Physics

There is no controversy about the need to wear a mask to reduce the possibility of COVID-19 transmission. Every scientific research that I've read supports that.

Here are some more from the physics side of it. This is approaching it from purely the point of view of physics of fluids.

Visualizing droplet dispersal for face shields and masks with exhalation valves

Visualizing the effectiveness of face masks in obstructing respiratory jets

On respiratory droplets and face masks

Zz.

Followup On Far-UVC Light Kills Airborne Coronavirus

This is a follow-up on the topic that I posted last time regarding evidence that far-UVC light can effectively reduce airborne virus transmission.

I read more about it, and found this extensive Physics World article that highlights the current development of the application of far-UVC light in virus sterilization. So obviously, this is a very active area of research right now. There are compelling evidence that far-UVC may be safe to human beings under limited exposure while still be effective in eliminating airborne viruses such as COVID-19.

But another issue that I've been trying to dig through is that, while far-UVC may be safer in terms of very short penetration depth into the skin and cornea, I haven't read much on possible ozone generation. One of the nasty effects of UVC light is that it can create ozone gas.

I sent to the International Ultraviolet Association webpage (didn't know one existed till recently), and went through their FAQs. One of them addresses the specific issue of ozone creation:

Does far UV (200 – 225 nm) generate ozone?

From a photochemical perspective, yes.

The Chapman cycle (Chapman, 1930) describes the counteractive processes of ozone formation and degradation from the interaction of light with molecular oxygen (O2) and ozone(O3). The rate of generation of ozone by far UV-C (known as the Herzberg continuum in atmospheric science) outweighs the rate of its degradation; the tipping point at which this generation/degradation balance flips is ~242 – 243 nm. (Andrew et al., 2003; Santos, Burini, and Wang, 2012), Far UVC (200-225 nm) only generates ozone in the upper atmosphere, where path lengths are very long. In a normal laboratory setting, ozone would not be generated because oxygen (O2) is a very weak absorber in the far UVC region.

As with any process, the risk of such hazards should be assessed on an application-by-application basis. A low power lamp operated in a well-ventilated area may not generate a measurable ozone concentration; a high-power system in an enclosed space may constitute a substantial risk.

Now, I don't quite understand why the "path lengths" have anything to do with ozone generation in the upper atmosphere, but it seems to imply that in a lab setting, far-UVC is not an effective ozone producer because it is a weakly absorbed by oxygen molecules. I can't get access to those articles while I'm at home, and I'm not even sure if my institution subscribes to any of those sources. So if anyone has more info on this, let's hear it.

This will be a tremendous way to reduce airborne transmission if it can be show to be effective and safe. But as with many things, it needs to be investigated carefully.

Zz.

Far-UVC Light Kills Airborne Viruses, And Safe To Humans Too?

First, let me give you the link to the paper that was published in Nature recently.

I actually have 3 separate topics to discuss here all based on this single paper.

The first is the science. UVC is used to kill viruses and sterilized stuff. We know that already. But it is also unsafe to human and we do not want to be exposed to it. But it turns out that far-UVC, having wavelengths in the range of 207-222 nm, is not totally harmful to human. In fact, ...

a regulatory limit as to the amount of 222 nm light to which the public can be exposed, which is 23 mJ/cm^2 per 8-hour exposure

means that humans can be exposed to this range of UVC for a limited amount of time. This is the basis of that research, i.e. using that wavelength and intensity of far-UVC, and see whether it can greatly "inactivate" the amount of viruses carried in airborne aerosols. They found that an exposure of just 25 minutes, very much below the regulatory limit. So there is a way to kill off viruses in airborne aerosols in the same space that human beings are around!

Certainly the implication of this research can be quite important, considering that airborne transmission of the COVID-19 virus is a strong possibility, which is why we are all wearing masks in public. There is now a way to greatly reduce such mode of transmission if this research is verified. The only thing I'm a bit weary about is the health and safety aspect. I know that they cited several sources that seems to show that the far-UVC is harmless to human, and the regulatory limits that have been imposed. Still, I'd like to have this one to be more well-established before I get really excited about it. For example, although the exposure limit is given in per 8-hour doses, how often can someone be exposed to that limit, say, in a month? Is that 8-hour dose limit per day? And certainly, long-term effect needs to be considered in anything of this sort.

But still, I find this result to be very promising, and it certainly is a new piece of information to me that far-UVC is actually not that harmful to humans.

The second aspect of this paper that I want to highlight is to the general public who often do not quite understand the nature of scientific publication. The main reason for scientists to properly publish their work is so that the rest of the community, especially those experts within the same field of study as the work, can scrutinize the work and evaluate its validity. So having something published does not automatically makes it valid. This is important to remember and understand. It requires scrutiny and verification by other experts in the field, and can sometime takes years. Think of how long of a time period from the moment the Higgs mechanism was proposed till its experimental verification at the LHC.

Therefore, it is imperative that a paper contains all the relevant information used to arrive at its conclusion or result. In this case, it is an experimental paper that produces a result. For it to be evaluated by other experts, it must contain all the necessary information. If you look closely at the end, the authors included their methodology, the exact equipment that they used, the experimental setup, the nature of the data analysis used, etc... etc. In other words, everything is as transparent as possible. It allows for someone else to repeat the experiment, and that is a crucial aspect of experimental science - REPRODUCIBILITY. It is something pseudoscience cannot do!

The third and final aspect of this paper is educational. I'm excited at the various values that they used in this paper, because I can already see myself using them in my general physics lessons. I'm already planning on using many of these numbers and asking my students to calculate (i) the amount of power per unit area based on the exposure time, (ii) the energy per photon of 222 nm light, (iii) the number of photons that impinges on a unit area during the exposure time, etc... etc. This will be perfect especially for the general physics course that I have taught that is aimed at life-science/pre-med majors. I always like taking something current, and very relevant to our times, to use as a material in our lessons. The students can immediately see first-hand that what they are learning is, in fact, very useful and has a direct effect on them beyond just wanting a good grade at the end of the semester.

So yes, I'll be holding on to this paper for quite some time.

Zz.

The Physics Of N95 Masks

Many, if not most, of us have heard of N95 masks when the pandemic first appeared, especially when there were reports of their shortages. Why are they so in high demand? This MinutePhysics video tells you why they are the ones that front-line health care workers need to be wearing.



Zz.

The Man Who Put His Head In A Particle Accelerator And Survived

OK, it is highly recommended that one doesn't try this. But it is still an amusing story.




Of course, if this were to happen today, in the US, there's a good chance that several major safety violations would have occurred and this facility would have been shut down.

Zz.

No Link Yet Between Cellphone Use And Brain Tumor

Another new studies that could not find any link between prolonged cell phone usage and brain tumors.

Y'know, people can make many speculative arguments back and forth on the issue of cell phone use and brain cancer. The FACT that we have right now are:

1. no established and clear link between cell phone and cancer, and
2. no physical mechanism for cell phone signals to cause cancer.

These are what we have currently. While people certainly are free to exercise caution if they want to, one should not confuse personal preferences and speculation with hard, valid evidence.

I'm more worried about drivers who use their cellphones while driving than I am about the cellphones causing cancers. If people are SO worried about their safety, why aren't they up-in-arms about that? There are enough documented evidence of accidents (including fatal accidents) that were direct results of using cell phones while driving. Instead, we get MORE publicity out of something that hasn't even been well-established, AND people who seem to already believe in them.

Makes no sense....

Zz.

The Physics of Weight Loss

I thought I'd post a link to this article about simple, basic, physics on weight loss. Although one can quibble a bit about 'arguing with Newton', I would say that nothing in here is surprising as far as the physics is concerned.

And we are all governed by the prevailing laws of physics that relate matter and energy. Calories are a measure of energy, and matter cannot be created without energy input. Arguments against the fundamental role of energy balance in weight regulation -- against calories in versus calories out -- are arguments with Isaac Newton. Folks, nobody wins an argument with Isaac Newton!
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There are, once we are done growing up, three ways we burn calories: physical activity, the generation of heat and just existing. There are technical terms for the second and third: thermogenesis, and resting energy expenditure (sometimes referred to as basal metabolic rate). What should be noteworthy right away is that you are not in charge of two out of the three!

You can choose how much exercise to do. But you don't get to choose how thermogenic you tend to be, and that can matter quite a lot. Like exercise, thermogenesis accounts for roughly 15 percent of total energy expenditure on average, but there is lots of variation on the theme of average. People who generate more heat from calories have fewer available with which to make fat. They tend to be people who can eat a bit more, and stay thin anyway.

 There ya go! That's your health info for the day! :)

Zz.

More Exercise = Higher GPA?

It is difficult to differentiate between the cause-and-effect observation versus the correlation observation when we deal with public health. So I wouldn't pass this out as a fact, but I'll just mention it.

It seems that the latest study presented at American College of Sport Medicine's annual meeting shows a correlation between college students who engages in daily 20 minutes of vigorous physical activity and higher GPA.

A study presented Thursday at the American College of Sport Medicine's annual meeting demonstrated the relationship and reinforced the notion that exercise reduces stress, improves performance and increases a sense of well-being.

Joshua Ode supervised the study at a university in the northern U.S., of students ages 18-22. Ode said, "If the students are improving in the classroom, it may create a better campus environment. You're creating more successful students, which is the goal of universities."

Researchers studied 266 undergraduates and defined moderate activity as those exercises which don't make you sweat or breathe hard, and vigorous activity for those which do, of any type. Their findings were consistent regardless of gender or major.

So then, let's examine this in light of the common stereotypes. We associate engineers, physicists, etc. as nerdy, wimpy looking guys, which presumably are thought to be smart and, therefore, would tend to have higher GPA. Don't look like they exercise much. Yet, we also often associate muscular, athletic, and physically fit guys as dumb jocks, not someone who would tend to have higher GPA.

So the stereotypes are in contradiction to the study, assuming that we buy into one or the other, or none. And yes, I'm being wishy-washy here. :)

Zz.