N95 respirators may not provide 95% protection against nanoparticles
A field test that involved placing an N95 respirator-wearing manikin at multiple sites and testing exposures using a nanoparticle counter found that while the respirator reduced exposures, in many situations it did not provide 95% protection.
Researchers positioned the manikin near concrete drilling and grinding activities, earthmoving, and woodcutting and used a commercially available nanoparticle counter to collect air samples and measure potential worker exposures and respirator efficiency.