29 CFR §1915.32

1. (a)When toxic solvents are used, the employer shall employ one or more of the following measures to safeguard the health of employees exposed to these solvents.
   1. (1)The cleaning operation shall be completely enclosed to prevent the escape of vapor into the working space.
   2. (2)Either natural ventilation or mechanical exhaust ventilation shall be used to remove the vapor at the source and to dilute the concentration of vapors in the working space to a concentration which is safe for the entire work period.
   3. (3)Employees shall be protected against toxic vapors by suitable respiratory protective equipment in accordance with the requirements of subpart I of this part and, where necessary, against exposure of skin and eye contact with toxic solvents and their vapors by suitable clothing and equipment.
2. (b)The principles in the threshold limit values to which attention is directed in § 1915.4 will be used by the Department of Labor in enforcement proceedings in defining a safe concentration of air contaminants.
3. (c)When flammable solvents are used, precautions shall be taken in accordance with the requirements of § 1915.36.