>>Sheila Kaplan, The New York Times Published: 17 Dec 2020 10:12 AM BdST Updated: 17 Dec 2020 10:12 AM BdST FILE — A wide variety of face masks, some with sports team logos, at a store in Cypress, Texas, on Nov 27, 2020. New filtration standards being developed aim to help consumers understand just how effective the masks they buy really are. (Go Nakamura/The New York Times) More than 100,000 varieties of face masks are currently for sale. They come in silk, cotton and synthetics; with filters and without; over-the-head and over-the-ears. They have sparkles and sunflowers; friendly greetings and insults; cartoon characters and teeny reindeer. "); } What they don’t have is a label that shows how well they block infectious particles, an omission that has frustrated public health officials during the coronavirus pandemic. Those experts note that there is a big range in the effectiveness of various designs, and some barely filter out particles at all.