This is a surgical mask. It is designed to protect You from Me. It is used during dental and medical procedures to prevent bacteria and viruses living on the medical staff from infecting the patient. During a pandemic it is useful for people who have respiratory symptoms like runny nose, cough, sneezing so that they will not spread whatever they may have to others. It however is not very effective at protecting the wearer from others. This has been shown during this pandemic and is why health care professionals tell you not to buy or use these masks for prevention. I have seen many news clips of people using these masks inappropriately and thus not getting the protection they are looking for.
This is one example of an N95 mask. It protects Me from You. This is part of the Personal Protection gear used in health care in an effort to prevent health care providers from getting the virus. If used properly they do prevent the virus from getting in the nose and mouth. (you need to add goggles or face shields to protect the eyes and gloves for hands. They are currently desperately needed in the health care setting. They will help to protect you, but if you buy and hoard them and prevent them from getting to health care providers, our providers will get sick and not be able to take care of others. Once there is an overabundance of these masks, which will happen soon, they are the best ones to use to protect your nose and mouth. If you touch the outside of the mask and rub your eyes before you have a chance to wash your hands then all bets are off. They are also very uncomfortable to wear.
This is a high filtration mask used in industry. It was not approved by the FDA for prevention of viral illness. However, theoretically it would likely work and since there is a shortage of approved masks they are being used and the federal government has has absolved the manufacturers of liability in using them for personal protection, which has increased their availabilty tremendously and help to relieve the mask shortage.
This plague mask is perhaps the first example of personal protective gear used during a pandemic. At the time they had no idea how disease spread. The belief was that it spread by bad gases or miasma. Since the plague was spread by fleas it likely did not work very well. (neither did killing all the dogs and cats) The part of the plague doctor’s garb that was likely more effective was the staff or cane. He used it to poke bodies to see if they were dead and could be removed. This was an early example of social distancing. (and cats and dogs cannot get the Covid 19 virus)
This is a halloween mask. There is no evidence that viruses will turn you into a monster but that is a common plot line in fiction. In the War of the Worlds it was germs that saved humanity since the invading aliens had no immunity to Earthly pathogenes, the book was written by H. G. Wells in 1898, made into a radio drama by Orson Welles in 1938, and made into several movies.
I hope this clears up some of the mask confusion I hear discussed nightly on Television. Stay safe stay well and carry on.