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Workers entering into confined spaces may be entering into areas that could have accumulated hazardous gases or that can become low oxygen environments, which can pose a risk for asphyxiation.  In addition, isocyanates and other agents contained in the SPF are potentially flammable and present a fire hazard when used in spaces that are not properly ventilated.  For example, the improper use of SPF in a confined space led to a fire in Falmouth, Masachussetts (May 2008) when a worker was trapped in an attic space and died.  The worker was installing SPF insulation in the attic and did not have proper ventilation or an escape route.

In addition, workers can be exposed to mechanical or electrical equipment inside confined spaces.  Some of the areas that workers enter inside a construction/retrofitting site may be considered confined spaces.
  • A confined space has limited or restricted means for entry or exit, and it is not designed for continuous employee occupancy. Confined spaces include, but are not limited to, underground vaults, tanks, storage bins, manholes, pits, silos, process vessels, and pipelines. For construction or reconstruction work attics, crawl spaces and overhangs with limited ceiling space or small space can be considered a confined space - especially for the purpose of SPF (29 CFR 1926 – General construction standard).
  • OSHA uses the term "permit-required confined space" (permit space) to describe a confined space that has one or more of the following characteristics: contains or has the potential to contain a hazardous atmosphere; contains a material that has the potential to engulf an entrant; has walls that converge inward or floors that slope downward and taper into a smaller area which could trap or asphyxiate an entrant; or contains any other recognized safety or health hazard, such as unguarded machinery, exposed live wires, or heat stress.
Employers need to look at the spaces that workers enter to determine if they meet OSHA’s definition of a confined space, and, if so, whether the space has any other associated hazards that make it a "permit-required" confined space. If workers need to enter a "permit-required" confined space, then the employer must develop entry procedures, including an entry permit, and train the workers. For further information on confined space hazards, the OSHA topic page on Confined Spaces should be consulted. In addition, the Confined Space Advisor software program is available as an additional resource for employers and workers in this industry.


Additional safety and health information is available on OSHA's web site and from the links listed below:

Accessibility Assistance: Contact the OSHA Directorate of Technical Support and Emergency Management at (202) 693-2300 for assistance accessing PDF and PPT materials.

*These files are provided for downloading.