1. National Institute for Occupational Safety and Health (NIOSH): “NIOSH-Approved Particulate Filtering Facepiece Respirators.” Available at https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/ (accessed June 20, 2016)
2. “3MTM Home Dust Mask.” Available at http://solutions.3m.com/wps/portal/3M/en_US/3M-Safety-NA/Safety/Product-Catalog/∼/3M-Home-Dust-Mask?N=5927440+3294427459+3294529207&rt=rud (accessed June 20, 2016).
3. “Antimicrobial Masks.” Available at http://www.breathehealthy.com/about-our-masks/antimicrobial-masks/ (ac-cessed June 20, 2016).
4. “Five and Diamond Dust Masks.” http://fiveanddiamond.com/collections/dust-masks (accessed June 20, 2016).