Examples of how respirators can be altered, voiding NIOSH approval:

 A manufacturer or vendor makes a modification to a respirator, unaware of the impact of the changes or the need to obtain new testing and approval (e.g. a manufacturer may change the way the straps are attached to the facepiece).

•   A third party, who is not authorized by NIOSH, makes changes to a NIOSH-approved respirator. This could also involve attempting to copy an approved product.

•   Wearers themselves modify a respirator in some way in order to enhance comfort or appearance, compromising their own protection (e.g. decoration is applied to an approved respirator to make it a fashion statement).

•   Respirators that were previously approved by NIOSH and had the approval revoked or rescinded are repackaged and sold under another brand.