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Alert: Flammable Vapours from Polyethylene (Packing) Foam

  • ISSN: 1195-5228
  • Revised: July 2009
  • Content last reviewed: July 2009

Hazard Summary:

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.

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.

Legal Requirements:

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

This Ministry of Labour Alert has no legal effect and does not constitute and is not a substitute for legal advice. If you require specific assistance with respect to the interpretation of a legislative provision and its potential application to you please contact your legal counsel.

Remember that while complying with occupational health and safety laws, you are also required to comply with applicable environmental laws.

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