42 CFR §84.178

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗

Resistance to airflow will be measured with a breathing machine as described in § 84.88.

(a)Minimum inhalation resistance must be greater than zero mm of water-column height.
(b)Maximum exhalation resistance must be less than 89 mm of water-column height.