CFR › Title 7 › Part 51 › §51.21267 CFR §51.2126Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗Copy linkParticles and dust means fragments of almond kernels or other material which will pass through a round opening 8/64 of an inch (3.2 mm) in diameter.