tors. Plans for any additional data gathering should be developed in consultation with experts in statistical sampling and measurement.

Conclusion 5-4: Manufacturers of multiple-sized facepieces often have difficulty obtaining certification for each individually sized facepiece.

Recommendation 5-4: Modify Certification Requirements. NIOSH should modify its certification requirements to encourage manufacturers to develop specific sizes designed to fit underrepresented anthropometric categories. Certification requirements should be modified to allow families of respirators (e.g., small, me-dium, and large) to be certified against a fit-test panel and not specify what por-tion of the panel each individual size respirator must fit, provided that the family adequately covers the entire panel.

Conclusion 5-5: The current size designations of small, medium, and large for respirators in product literature are not adequately informative for wearers and fit testers.

Recommendation 5-5: Develop Improved Descriptions of Face Mask Sizes. NIOSH should encourage manufacturers to develop improved methods of de-scribing facial sizes and shapes in product literature. For example, NIOSH and manufacturing companies should further explore the use of face panel images, and respirator containers should include corresponding pictures of small, me-dium, and large sizes, and long/narrow and small/wide face pictures.