Please understand I am not a doctor, I am just an engineer who because of allergies knows a bit about filtration, nothing more nothing less. Below is a common sense review of this “cotton mask”.
First of all it is not cotton, it is a mix of 94% cotton and 6% Lycra and this is important for 2 things. Cotton is not a very good air filter material, it will pass a lot of the virus, much better than nothing but not that good, adding Lycra to it improves its filtration significantly.
This leads us to the second point, indoors in 26C which is not at all hot, the mask became uncomfortably hot in minutes, not to the degree that i would risk my life of the life of others but it was not the best thing. N95 by comparison are much more comfortable to wear, but the difference in cost and ability to be mass produced is huge.
Comfort wise on the ears it was good for me but your mileage will vary, cotton/lycra mixes have a bit of elasticity and thus will allow for a good fit given that they are not too tight or too big, getting a good fit is important and they are offered in sizes. You will have to buy different size since once opened this is useless or even dangerous and that will lead me to an important point you can read later on.
Looks wise it is pretty ok, not a fashion statement but still nice and sharp looking, at least i look better in a mask since it hides my big nose. I am sure with time more designs will be made and those that value fashion above all may with time be satisfied.

Let me point to another important issue, wearing masks is an important part of Japanese and other Eastern cultures and it is time for the world to emulate them not just now, but anytime anybody has a cold they should wear something like this, that is just being a responsible human acting for the WE not the ME, for the ME will never be able to survive without the WE.
Lets talk about the most important part filtration.
The standards for this and others to come in Egypt all follow a standard put by the government. So lets assume it has good but not great filtration IF THE AIR PASSES THROUGH IT AND NOT FROM ITS SIDES. Unlike an N95 this does not fit the nose well nor does it have a metal adjuster on the top like the n95 so you can make air always pass through the cloth and that i think is by design.
Why would they design it so that is does not work well? Well let me tell you that even if it is not designed well i can show you how it could be closer to n95. They did not design it like the n95 because it is not an n95, it does not use a professional filter, a professional filter is an expensive piece of equipment that sacrifices re usability to give you a filter that filters well and does not make breathing through it very hard.
Let me describe it so you get it, if you breath through an n95 with all air passing only through the filter and nothing from the sides or from the nose gap area that you close with the metal in the n95 for 8 hours nothing bad will happen to you but if you do that with this material you will not be able to breathe after a few minutes, breathing through it is hard, it is not and was not initially designed to be a filter material. If this mask is closed as the n95 you might pass out in 5 minutes or so.
As is it will protect you but not like what is needed by doctors. But you can get better protection from it and i will show you how.

Now for the hard part how to make it closer to n95 all the time, you can not. If you put a nose metal part like the one on n95 you will pass out, you will die and driving in it will kill people. What you can do is the following when you are in a higher risk situation, like when going to a supermarket for a few minutes, when someone is closer to you than should be, when someone is close that looks sick, you can breath IN not out through your mouth in such a way that all the air passes only though the filter material. Look at the video below, you will see the part over my mouth move inside as I use negative air pressure of my inhalation to make a seal that makes all air i breath go through the mouth part.
Take care again you can only do this for a few minutes and some of you might not even be able to keep that for 3 minutes without feeling dizzy.
A real problem
As you know these are most probably made by hand in a factory, if the worker that did this had covid-19 breathing through this mask would be terrible, it will infect you and not protect you. I strongly suggest you wash it first as you do with most new clothes. But what I would like to see from the producers of such ( hint you know who you are ) is a production date stamp on the mask, if 3 or 4 days have passed then it is good to use. I know the supply chain from factory to end user may take more than this, but sometimes people in the supply chain will take these or sample them and that would be a great thing to have, production date and contrary to food a do not use before date.
Over all remember this is not about you not being infected it is about everybody not infecting every body, if someone is not wearing a mask tell them they should, you will not be able to grin at them because they do not see your face. Tell them that you are protecting them and they have to reciprocate.

للضحك
امي اكيد من الاويلأ
زمان لاما شافت اللباس الملون دعت عليا
يا عياقتك – الله يلبسك كوتونيل علي وشك
Does the mask reduce your oxygen?
Here comes the test. I used the oxymeter on Galaxy note 9. I made sure it works by testing in normal rest and then with deep breaths and with deep breaths my o2 level usually goes up to 97 from 95 base line.
Now to test you have to have standard conditions. I stayed in bed just typing this, after a time i did my base line multiple times all in 95 to 96 range but most in 95. Now i put on the mask and stayed doing the same stuff for half an hour and i measured making sure i did not do deep breaths a lot. After half an hour the o2 level was 94. A small change but a change none the less so i soldiered on and continuing for 45 minutes. after about 40 minutes my o2 was 96. After 43 minutes it was 94 again and finally after 45 minutes it was 94.

Then i closed the nose gap like n95 with my hand as in the picture and for 5 minutes i measured 4 measurements each 93. After i continued and breathed like in the video breathed through my mouth making sure all the air came through the fabric and exhalation was normal. O2 rose to 95,94,95, but realize this, breathing with your mouth is conscious breathing not like the automatic breathing of the above tests. I also think that closing the nose area is superior filtration wise because air through the fabric will be slower and thus deposit more particles. Although the o2 is ok, breathing with mouth and closed gap is harder, and i would not under any circumstance tell you to do it for the whole day. But in higher risk situation it could be great.
As we see there is not much change if at all under these conditions. Wearing this for people that do not do manual labor is very safe.
Of coarse the test is not indicative of real life, in real like you walk, you rest and you sometimes have to run to catch a bus, i do not know the effect of the mask in such situations where more energy is being spent and thus more oxygen needed, to do a scientific test would need something like a treadmill on a constant speed and before and after, since i can not really run i will not do unless a lot of people really demand it, then i can see how this can be tackled. Needless to say if you have an office job or even are a cashier at a supermarket, wearing the mask will not likely affect your oxygen levels.
Please do not treat the above as facts, i tried to use the scientific method but this is not a comprehensive test only a test to see if there are huge problems with wearing this mask.