June 1, 1973

MEMORANDUM FOR: REGIONAL ADMINISTRATORS/OSHA

FROM: DONALD E. MACKENZIE Director, Field Coordination

SUBJECT: Clarification of 29 CFR 1910.107 (b)(5)(i) Average Air Velocity of Spray Booths

The average air velocity requirements over the open face of the booth stated in this paragraph for spray finishing operations using flammable and combustible liquids were taken from NFPA-33-1969 and pertain to those hazards associated with fire protection or the removal of flammable vapor accumulation from the interior of the booth during spraying operations. This paragraph applies to maintaining the concentration of flammable vapors below the lower explosive limit (LEL) in a spray booth but does not apply to maintaining operator exposures to within the permissible exposure limits (PEL).

The paragraph does not apply to the determination of feasible engineering controls of potential health hazards found from the use of toxic materials (i.e. zinc chromate, toluene, etc.). In areas where a health hazard has been established the CSHO/IH shall determine on a case by case what is to be adequate engineering controls and effective work practices that would reduce employees exposure to within the health standards. This may include modification or new booth design, modification in application, or increasing the air velocity beyond that stated in 107(b)(5)(i).