There are differences across the major guidance documents regarding the limits for both viable and non-viable particulates. The ISO 14644-1 deals entirely with non-viable particulate sizes for various clean-room classifications. The European Commission Annex one and the United States Pharmacopeia focus on both viable and non-viable particulates within grades A (class 100), B (class 1000), C (class 10,000), and D (class 100,000). The tables below compare the guidance documents and help to display the inconsistencies between all the main clean-room classifications.