N95 masks made from synthetic plastic fibers are most common. These plastic fibers are similar to the fibers in synthetic and polyester shirts many people wear. Besides the filter material, N95 masks can also include other materials, such as metal. The straps of some masks are made from polyisoprene.
Click here to read more on those materials and how the plastic fiber can help to trap tiny pollutant particles: https://smartairfilters.com/en/blog/n95-masks-made-from/