I am talking about the math 0.3 microns is actually 3 tenths of a micron, that is what I am asking the forum is about math so if you have an particle that is 0.012 nanometers how much smaller is that than 3 10th's of a micrometer because I don't really understand how to do that math. I micrometer is 6 0's, I think a nanometer would be 9 0's . What is the proper math to figure out how much smaller is one thing from another. It would be improper to discuss anything in this forum that is not math.
Nanometers are 100 smaller than micrometers, my problem is 3 tenths of a micro meter. How do I figure the difference between in size between 3 tenths of a micrometer and 0.012 nanometers? maybe some could explain or give me the equation for figuring the difference between .3 meters and 0.012 micrometers. I know that if you multiply 0.012 X 250 you get 3. I get that if you divide 3 by 0.012 you get 250. Where I get confused is once we go into decimals. if I divide 0.3 by 0.012 I get 25, but what is that 25 telling me.
The point .3 I am talking about is 3 tenths of 0.000001. I can't rap my thought around that. I struggle with numbers that go right instead of left. So if a micrometer is 0.0000001 then 3 tenths of that is 0.0000001/10 x3 I realize this must be the moron way of getting there, but would that would be correct 0.00000003, that's three tenths of a micron? Then I need to understand when it says 0.012 nanometers; nanometers have 9 0's so if it says something is .012 nanometers and there are 9 places in nanometers it is really written as 0.000000012? and if I want to know how smaller that is than 3 tenths of a micrometer then I would divide 0.00000003 by 0.000000012 and yes I understand that all the zeros cancel out and then that would mean .3/.12 and that gives me 2.5 times smaller ... I struggle with this stuff, but I am trying to think my way through it.
Rather than count zeros, you should focus on the location of the decimal point relative to the
end of the number. One micrometer has 5 0's before the 1 (0.000 001), and 11 micrometers has 4 0's (0.000 011). (Spaces help in counting.)
The way I think of it, micro means millionth, so 1 micrometer is 1/1,000,000 m; if we move the decimal place in both numerator and denominator 6 places to the left (the number of 0's in 1,000,000), we get 0.000 001/1.000000 = 0.000 001.
A nanometer is 1/1000 of a micrometer (not 100). For that, you move the decimal point 9 places: 1/1,000,000,000 = 0.000 000 001.
So 0.3 micrometer is 0.000 000 3 m, and 0.012 micrometer is 0.000 000 012, where we have 6 zeros tacked on to the left of the number of micrometers. But since the units are the same, the ratio of these is just the ratio of 0.3 to 0.012: 0.3/0.012 = 25, which says that 0.3 um is 25 times 0.012 µm, and 0.012 µm is 1/25 of 0.3 µm.
While you should be asking science questions of scientists, I want to make a couple comments about the droplet issue, based on things I have heard from good sources.
About the mask thing, there are videos that show the difference of exhaled repository water droplets, that's water droplets. Which are 1 micron to 10 microns, but we are talking about a virus that is nanometers. My brother argues that a mask if it stops 50% of then it is better than nothing. I argue it only takes 1 tiny COVID-19 to infect, kind of like facing a firing squad you have 100 guns pointed at you but only 50% have real bullets what do you think your chance is, masks are useless. But the math of trying to understand 3 tenths of a micrometer vs 0.012 nanometer, I wanted to understand that, and that is why I came to a math forum. I have lots of other math questions but they should not be asked in this forum, I am very excited I found the forum and I am looking forward to learning much more. An opinion is just that, just what one thinks, but math as far as I know is an absolute.
First, it turns out that the 0.3 micron size is used as a standard at least in part because that is the hardest size to stop; somehow (I think it involves electrostatic attraction, or just more random movement), smaller particles are actually easier to stop! In fact, your quote in post #11 said this: "when tested against very 'small' particles that are the most difficult size to filter (approximately 0.3 microns)."
I just did a quick search for good sources for this, and here are the first two I found, which are not necessarily the best, but come from reliable sources:
www.cidrap.umn.edu
Every filter has a particle size range that it collects inefficiently. Above and below this range, particles will be collected with greater efficiency. For fibrous non-electret filters, this size is about 0.3 micrometers (µm); for electret filters, it ranges from 0.06 to 0.1 µm. When testing, we care most about the point of inefficiency. As flow increases, particles in this range will be collected less efficiently.
We made measurements for three variations: combining one layer 600 TPI cotton with two layers of silk, two layers of chiffon, and one layer of flannel. The results are also compared with the performance of a standard N95 mask. All three hybrid combinations performed well, exceeding 80% efficiency in the <300 nm range, and >90% in the >300 nm range. These cloth hybrids are slightly inferior to the N95 mask above 300 nm, but superior for particles smaller than 300 nm.
The second reference says that cloth masks (properly designed) work better than N95 for the smallest sizes; and 300 nm (which is the same as 0.3 µm) is that least efficient point they are basing their study on.
Second, I have heard good people say that quantity matters; a single virus is far less likely to cause infection than a thousand of them. For the reason, you'll have to ask the scientists. But here is one reference:
Please read this link to learn about the author and background to these posts. It seems many people are breathing some relief, and I’m not sure why. An epidemic curve has a relatively predictable upslope and once the peak is reached, the back slope can also be predicted. We have robust data from...
www.erinbromage.com
In order to get infected you need to get exposed to an infectious dose of the virus; based on infectious dose studies with other coronaviruses, it appears that only small doses may be needed for infection to take hold. Some experts estimate that as few as 1000 SARS-CoV2 infectious viral particles are all that will be needed (
ref 1,
ref 2). Please note, this still needs to be determined experimentally, but we can use that number to demonstrate how infection can occur. Infection could occur, through 1000 infectious viral particles you receive in one breath or from one eye-rub, or 100 viral particles inhaled with each breath over 10 breaths, or 10 viral particles with 100 breaths. Each of these situations can lead to an infection.
Not entirely encouraging, but the point is that we need to both reduce the rate at which particles come at us, and the length of time we are exposed. Masks are far from perfect, but can help keep you from infecting others (and their masks can help keep them from infecting you). Isolation is better. I myself am not terrified, but am cautious.
Edit: Just after I sent that, my wife passed me this article on mask usage:
Masks should not be a political issue. They are a public health issue. But they seem to have stirred up a whole mess of fuss for various reasons. I hope I can break it down simply here and demonstrate their importance in reducing SARS-CoV2 infections in our communities. When we breathe, talk...
www.erinbromage.com
But, again, I'm not an expert, so I'm saying this only to suggest possibilities.
