Must either spray booths or spray rooms be used to enclose or confine all spraying operations covered by 29 CFR 1910.94 and 29 CFR 1910.107?

OSHA says that the health hazards of spray finishing operations are primarily covered under the OSHA standard at 1910.94—Ventilation, although that standard also deals with fire and explosion hazards. Only the latter hazards of spray finishing operations are covered by 1910.107—Spray finishing using flammable and combustible materials. 1910.94(c)(2) states that spray booths or spray rooms are to be used to enclose or confine all spray finishing using organic or inorganic materials. Since the primary purpose of 1910.94(c) is to protect health, failing to perform spraying operations in a spray booth or spray room would be considered a de minimis condition of 1910.94(c), if the appropriate PEL in Subpart Z of Part 1910 is not exceeded. See the attached letter to Dee Woodhull, dated March 28, 2008.

Thus, if no OSHA PEL is exceeded during spray finishing operations, only then does the OSHA standard at 1910.107 apply. That standard does not have an enclosure provision similar to 1910.94(c) requiring that all spray finishing using flammable and combustible materials be confined to spray booths or spray rooms. However, the 1910.107 standard allows spraying operations only in predetermined spraying areas. Paragraph 1910.107(g)(l) requires that “[spraying shall not be conducted outside of predetermined spraying areas.” Paragraph 1910.107(a)(2) defines a “spraying area” as “[any area in which dangerous quantities of flammable vapors or mists, or combustible residues, dusts, or deposits are present due to the operation of spraying processes.” OSHA interprets “dangerous quantities of flammable vapors or mists” in 1910.107(a)(2), to be areas with concentrations exceeding 25% of the lower flammable limit (LFL) of any chemical used at any time during the spray finishing operations, without the benefit of ventilation required under the standard. See 1910.107(d)(2) (adequate ventilation shall be provided to remove flammable vapor, mists, or powder) and 1910.106(a)(31) (ventilation is adequate if it prevents significant quantities of vapor-air mixtures in concentration over one-fourth of LFL). OSHA interprets “combustible residues ... [or] ... deposits” as residues or deposits of any sprayed material whose MSDS or other sources indicate combustibility, and which have not been cleaned from the previous day's spraying activities. See 1910.107(g)(2) ( “All spraying areas shall be kept as free from the accumulation of deposits of combustible residues as practical, with cleaning conducted daily if necessary.”) For an explanation of dangerous quantities of combustible dusts, see the last paragraph of this memorandum.

However, OSHA says that one operation that does require an enclosure is the spraying of organic peroxides or other dual component coatings, which according to paragraph 1910.107(m) must be conducted in approved sprinklered spray booths. Section 16.2 of NFPA 33-2007, Standard for Spray Application Using Flammable or Combustible Materials, provides that spray application operations that involve the use of organic peroxide formulations and other plural component coatings may be performed in spray areas (and not spray booths) that are protected by approved automatic sprinkler systems. OSHA regards that provision as effective as 1910.107(m). Thus, with regard to fire and explosion hazards associated with spraying organic peroxides or other dual component coatings, if an employer has met all of the requirements of NFPA 33-2007, but the employer's spray finishing operation is not enclosed and not conducted within spray booths or spray rooms in accordance with 1910.107(m), then OSHA would consider the lack of enclosure as a de minimis condition and no citation would be issued for this condition.