How effective are cotton masks?

Are cotton masks useless? Doctors have been using masks for decades to treat patients that have been infected with different kinds of diseases, but they mostly wear surgical masks, which are more effective than standard cloth or cotton masks. According to the CDC, cloth or cotton masks are generally worse at filtering the Coronavirus, but they can provide better protection if designed properly. For example, wearing multi-layered masks designed to fit around the face with effective water droplet resistance and a higher number of threads and weaves, like N95 masks, will lead to better protection. But cloth and cotton masks are still better than nothing. The United States Environmental Protection Agency (EPA) says that the thin, three-layered mask blocked 26.5 percent of particles while a two-layer woven nylon mask with a inserted filter and metal nose bridge blocked 79 percent of particles on average. So a cotton mask is still better than nothing.