Standard Interpretations - Table of Contents Standard Interpretations - Table of Contents
• Standard Number: 1910.94; 1910.94(c); 1910.107; 1910.107(a)(2); 1910.107(c)

OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.


July 14, 2009

MEMORANDUM FOR: JOHN M. HERMANSON
Regional Administrator

FROM: RICHARD FAIRFAX, Director
Directorate of Enforcement Programs

SUBJECT: SPRAY FINISHING OPERATIONS CITATION GUIDANCE

This is in response to your request for guidance in the issuance of citations related to spray finishing operations. You asked three questions:

  1. 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?

  2. May a citation be issued for a violation of paragraph (b)(1) or paragraph (b)(2) of 29 CFR 1910.303 instead of 1910.107(c)(6) if:

    1. the electrical equipment used in or near an area where the spray finishing operation is performed is not subject to deposits of combustible materials; and

    2. the location where the spraying operation is performed does not meet the definition of a "spraying area" in 1910.107(a)(2)?

  3. How should compliance officers document dangerous quantities of flammable vapors or mists, or combustible residues, dusts or deposits before citations under 1910.107(c) are issued?

In response to your first question, 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, 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 shall be issued for this condition.

In answer to the first part of your second question concerning citation guidance for electrical violations in or near an area not subject to deposits of combustible materials, citations under 1910.107(c)(6) shall be issued because it is the vertical standard, rather than 1910.303 or .307(c)(2), which are horizontal standards. In accordance with 1910.107(c)(6), electrical and wiring equipment [not] subject to deposits of combustible dust residues but located [in] a spraying area shall be of explosion-proof type approved for Class I, group D locations and shall otherwise conform to the provisions of subpart S of this part, for Class I, Division 1, Hazardous Locations. In accordance with 1910.107(c)(6) electrical wiring, motors, and other equipment outside of but within 20 feet of a spraying area and not separated by partitions shall not produce sparks under normal operating conditions and shall otherwise conform to the provisions of subpart S of Part 1910 for Class I, Division 2 Hazardous Locations.

In response to the second part of your second question, which pertains to an area where a spraying operation is performed, but the location does not meet the definition of a spraying area, citations for violations of Subpart S shall be issued, as appropriate.

In order to issue a citation for a violation of 1910.107(c) or (d), the compliance safety and health officer (CSHO) must document the area in which dangerous quantities of flammable vapors or mists, or combustible residues, dusts, or deposits may be present due to a spraying process. There must either be dangerous quantities of flammable vapors or mists or there must be combustible residues, dusts, or deposits in order to cite the employer for violations of the provisions noted above. In order to document flammable vapors or mists, the CSHO must use a combustible gas detector (indicator). However, if a spraying operation is not being performed during an OSHA inspection, then CSHOs should determine the composition of the sprayed material from its MSDS or other sources, and refer to the example and the associated formula provided in 1910.94(c)(6)(ii) to determine whether the volume of air being ventilated is greater than or equal to the volume of air in cubic feet necessary to dilute the vapor from one gallon of any of the solvents in the sprayed material to 25% of the LFL. To document combustible residue or deposits, the CSHO must document whether the MSDS or other sources for the sprayed material indicate combustibility and whether the deposits or residue is removed daily. To document combustible dust accumulations, CSHOs should consult NFPA 654, Standard for the Prevention of Fires and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids (2006 Edition). Annex D of NFPA 654 contains guidance on dust layer characterization and precautions. The material in Annex D is an idealized approach based on certain assumptions, including uniformity of the dust layer covering the surfaces, a bulk density of 75 lb per cubic foot, a dust concentration of 0.35 oz/per cubic foot, and a dust cloud height of 10 ft. It indicates that immediate cleaning is warranted whenever a dust layer of 1/32-inch thickness accumulates over a surface area of at least 5% of the floor area. Also, dust samples must be sent to the Salt Lake City Testing Center to determine if there are any violations of 1910.107(c), which deals in part with electrical sources of ignition.

If you have any questions, please contact Sanji Kanth of the Office of General Industry Enforcement at (202) 693-2135.

[Corrected on 01/23/2012]

If you have any questions, please contact Sanji Kanth of the Office of General Industry Enforcement at (202) 693-2135.


Standard Interpretations - Table of Contents Standard Interpretations - Table of Contents