Mass. Gen. Laws ch. 149, § 18B: Confined spaces; ventilation; longshore and waterfront operations

Section 18B. Before allowing employees to enter confined spaces where flammable, poisonous, asphyxiant, suffocant or anesthetic vapors, gases or dusts are likely to exist, the area shall be made free of the hazardous substance; employees shall be advised of the hazard; adequate ventilation shall be provided; and proper respiratory equipment shall be provided where necessary.