Exposure to CO₂ release from dry ice storage

IMCA has learned of the following incident whereby an unexpected hazard arose when stowing refrigerated stores. A vessel was in the process of mobilising for a prolonged spell offshore and had ordered a significant amount of food stores, which arrived in a non-refrigerated truck. Fresh vegetables and fresh milk had been loaded into the fridge, to be stored by a steward.

While storing the milk and vegetables, the steward began to feel unwell. He was relieved by the chief cook, who almost immediately detected a strange atmosphere and felt unwell as well. He left the fridge and was noticed by the first officer to be unsteady on his feet as he was climbing the stairs near the food stowage area. The first officer assisted the chief cook up the stairwell to an office, where the steward was still recovering from what was initially assumed to have been a cold operating environment. The steward received oxygen as a precaution. He was transported to a local medical care facility for further evaluation and released to full duty. The chief cook recovered immediately after leaving the area.

An ‘all stop’ was called and the area was evacuated. Ventilation and appropriate PPE were utilised to carry out an investigation. During early investigations it was found that the (fridge) area was oxygen deficient. At this time, the type and concentration of gas were undeterminable.

A refrigeration technician was requested and arrived on board later that day. He was able to confirm, with detection equipment, that the gas was carbon dioxide. The CO₂ was found to be emanating from solid CO₂ blocks used to pack the fresh milk. This had not been noticed as the stores had been loaded, but as it evaporated into the atmosphere in and around the stowage area, it had caused a build up of CO₂ which displaced the oxygen content.

All actions taken were analysed by using a job safety analysis process to identify all hazards and the appropriate steps to mitigate each. The two crew members entering the contaminated area used self-contained breathing apparatus (SCBA) and removed all packages of milk and the CO₂ blocks to outside the vessel, where the CO₂ would safely dissipate. The refrigeration unit was then restarted and the area was ventilated overnight to ensure complete discharge of the gas.

Historically, only frozen goods had come with dry ice packing which, in this instance, caused an unidentified hazard to be brought into the confined space stowage area by the galley crew.

The company involved has noted the following lessons learned:

  • Confined or enclosed spaces may present hazards such as oxygen-deficient or enriched atmospheres, flammable atmospheres, toxics atmospheres, or a combination of these;
  • When working in confined areas, it is extremely important that personnel maintain awareness of their environment and the problems that result when foreign substances are released into the atmosphere. In this case it was dry ice that caused the problem.
  • Through the actions of the crew in evacuating, ventilating, conducting atmospheric testing, completing a JSA and using SCBA to remove the dry ice before re-entering the enclosed environment, a more serious scenario was avoided.