Alert: Flammable vapours from polyethylene (packing) foam
Learn about the necessary precautions for handling and storage of polyethylene foam.
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A worker was killed after entering an unventilated trailer that was filled with polyethylene foam and stored over a warm weekend. The worker entered the trailer and reportedly lit a match. The worker received severe and extensive burns following an intense fire from within the trailer.
As part of the manufacturing process, isobutane (2-methylpropane) is used as a "blowing agent" to expand solid plastic into polyethylene foam. The isobutane initially fills the airspaces within the foam but, over time, it leaks out and dissipates into the atmosphere. This is most rapid immediately after manufacturing. Before being shipped, the product should be cured in a ventilated warehouse to allow for the safe escape of gases. Also, experts should be consulted to establish the specific time period required for this to be considered complete.
If stored in an environment that is unventilated, the gas will accumulate. Furthermore, if temperatures are elevated, the rate at which the gas escapes from the foam will increase.
Isobutane gas is flammable at concentrations in air between 1.9 per cent and 8.5 per cent.
This resource does not replace the Occupational Health and Safety Act (OHSA) and its regulations, and should not be used as or considered legal advice. Health and safety inspectors apply and enforce these laws based on the facts they find in the workplace.
Locations and sectors
This type of hazard can be found in any industrial establishment involved in the manufacturing of polyethylene packing foam and in any workplaces that use, handle or store it, e.g., in warehousing, loading/unloading areas, during transportation, etc.
The Regulation for Industrial Establishments [R.R.O. 1990, Regulation 851] under the Occupational Health and Safety Act requires that any process likely to produce a gas, vapour, dust or fume that can accumulate to form an explosive mixture, be situated in an area separate from other operations and have adequate ventilation. No potential sources of ignition, including smoking, are permitted in areas of an industrial establishment where there are potentially explosive concentrations of a gas, vapour, dust or fume.
The Workplace Hazardous Materials Information System (WHMIS) Regulation [R.R.O. 1990, Regulation 860] applies to any controlled products used, handled or stored within a workplace to which a worker is likely to be exposed.
Under the Occupational Health and Safety Act, employers are required to develop and post a workplace health and safety policy and develop a workplace program to implement the policy. Good practices for employers to implement in order to address the hazards as part of a workplace health and safety program, include, but are not limited to, the following:
- Adequate and unobstructed ventilation for the storage of products manufactured with flammable agents such as isobutane which may build up in the surrounding air as by-products.
- Storage in environments where temperatures are kept as cool and constant as possible.
- Written notification to carriers alerting them to the potential hazards associated with the load they are to haul.
- Pre-qualification of carriers with respect to their health and safety policy and program; e.g., carrier program that trains and informs all workers and subcontractors about potential hazards, monitors adherence to procedures to avoid sources of ignition and to provide adequate ventilation, ensures identification of hazards on bills of lading and trucks/trailers, driver cautions, etc.
Reference for flammable concentration in air
Dangerous Properties of Industrial Materials, 11th Edition, Vol. III, N. Irving Sax and Richard J. Lewis, Sr., 2004, Wiley Interscience, New Jersey