Does this scenario sound far-fetched? Believe it or not, it’s a very real and very common occurrence. Fires caused by spontaneous combustion or chemical reaction accounted for an estimated average of 14,070 fires per year between 2005 and 2009, according to the United States Fire Administration’s National Fire Incident Reporting System (NFIRS) and the National Fire Prevention Association’s (NFPA) survey.
According to the NFIRS, fires caused by spontaneous combustion contributed to:
- 3,200 structure fires
- 1,150 vehicle fires
- 5,250 outside non-trash and unclassified fires
- 4,460 outside trash or rubbish fires
Because the fires are coded as spontaneous combustion or chemical reaction, there is no way to determine what the exact circumstances were (spontaneous combustion versus some other kind of chemical reaction). In addition, the NFIRS reports that these fires tend to occur in the afternoon or evening hours after they have had an opportunity to smolder and eventually ignite.
What causes spontaneous combustion? One of the major culprits at construction sites involves paint, stain or solvent-soaked rags improperly stored or discarded in a trash can or cardboard box in the project’s garage or structure.
Oily rags improperly stored or discarded can slowly heat to its ignition point through oxidation. If this heat has no way to escape, the temperature can elevate enough to ignite the rags. The hotter the air temperature, the faster the rags can ignite.
Contractors can reduce their risk of this hazard by sharing the following mitigation actions:
- Provide metal containers with self-closing lids and store outside of the project in an area free and clear of combustible debris, brush and organic materials
- Do not dispose of rags in cardboard boxes, trash containers or debris piles
- Consider utilizing noncombustible solvents or water-based materials whenever possible
- Store oily rags in a “listed disposal container” per NFPA 241, 5.4.3, OSHA 1926.25(c) and OSHA 1926.252.
- Dispose of and remove combustible wastes daily per NFPA 241, 5.4.1.
- Ensure fire extinguishers are available in accordance with all OSHA requirements at job sites
Fires due to the spontaneous combustion of oily rags can cause significant property damage and potentially the loss of life. The appropriate use, storage and disposal of rags can help reduce or eliminate the risk of spontaneous combustion fires.