Ask the Expert, Personnel Safety

Ask the Expert: Paint Booth Ventilation

In our latest installment of Ask the Expert, brought to you by the team of industry experts at EHS Hero®, we look at a recent question from a subscriber asking about whether paint booth ventilation shafts are permit-required confined spaces. See what the experts had to say.

Spray Painting

Q: Is a paint booth ventilation shaft a permit-required confined space? Our entire system is locked out and a strong air flow always brings in fresh air. Although access to the booth is tight, the worst thing about the space is minimal paint dust buildup.

A ventilation shaft for a paint booth could be considered a permit-required confined space under OSHA rules if it is large enough for a person to physically enter (i.e., placing any part of the face or body into the space), has limited or restricted means of entry or exit, is not designed for continuous occupancy, AND it has at least one of the following four characteristics:

  • Contains or has a potential to contain a hazardous atmosphere;
  • Contains a material that has the potential for engulfing an entrant;
  • Has an internal configuration in which an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor that slopes downward and tapers to a smaller cross section; or
  • Contains any other recognized serious safety or health hazard (e.g., residues on surfaces that could cause slips and falls, objects or equipment that could restrict movement, hazardous chemicals, hazardous energy from electrical equipment, steam pipes, or pressurized systems)

The OSHA confined space rule at 29 CFR 1910.146(a) requires you to evaluate potential spaces to determine whether permit entry is required, or if entry is allowed without a permit. For example, you mention that paint dust buildup is “minimal,” but “minimal” concentration of dust in the atmosphere needs to be quantified: the paint dust may be a recognized serious health hazard or contribute to a hazardous atmosphere until you quantify the potential exposure through air monitoring.

According to OSHA’s FAQ page about confined spaces, a paint spray enclosure is considered to have restricted means of entry or exit if an employee has to crawl to gain access to his or her intended work location. Similarly, an access door or portal that is too small to allow an employee to walk upright and unimpeded through it will be considered to restrict an employee’s ability to escape. See the OSHA confined space FAQ page at

There are criteria to classify a confined space as not requiring an entry permit. For example, if you can demonstrate and document that the only hazard is an actual or potentially hazardous atmosphere, and it has been determined that the forced air ventilation alone is sufficient to maintain safe entry, and monitoring is conducted, then the space may be classified as non-permit required. See the BLR analysis for confined spaces at, then scroll down to the section ALTERNATIVE TO FULL PERMIT ENTRY for the bulleted list of criteria for entry without a permit.

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