They won't protect you and you're just adding more waste to the land and water... They also don't cover your eyes which is probably how most infection gets in.

According to healthline and many other sources, COVID-19/the novel coronavirus has a diameter of ~120nm while face masks only have a filter up to 300nm. I've been looking through information on facemasks have two main purposes:
1. Industrial: This is where someone is commonly working with small particles that need to be blocked going into their respiratory tract, such as wood workers and the like. Thre is also a use case for these in China for their pollution levels since carbon particulates above 100 micrometers in size are known for increasing the risk of asthma and 300 micrometers are known for producing carcinogens pretty quickly (I hope i got that the right way round).
2. Medical: Contrary to what a lot of people would thiink, the N95 model (I'm told is the most popular in medicine) actually just stops the surgeon/practitioner from projecting salivery deposits onto a patient and aren't actually for reducing the amount of infection spread between the two - probably the reason most doctors actually don't wear these. Quarrentine outfits probably give the doctor a certain amount of time in with a patient before they're changed, or have additional tuping to allow for them to receive air from outside the quarrentine unit (either that or they have more advanced filters, there's probably some fancy electrostatics devices for this sort of thing).