$4.95 -Cotton Face Mask PM 2.5 Mask With Filter Washable Reusable | eBay
PM 2.5 Mask, Grey - Reusable, Washable Cotton Face Mask - 4 Pieces with 8 Filters - Adjustable Ear Bands and Nose Bridge - Removable Air Valve Protects Against Pollutants and Other Airborne Particles - Walmart.com