This report presents the results of inhalation and exhalation resistance, filtration performance, and organic vapor (OV) service life testing on NIOSH-approved and counterfeit respirator P100 filters, chemical cartridges, and combination cartridges. NIOSH’s pilot project showed: 220/240 fraudulent P100 filters 124/124 fraudulent combination cartridges 8/8 fraudulent chemical cartridges failed to meet all required NIOSH performance tests....