TT Talk - It's only a steel box
It may be difficult to look at a container and equate it to an enclosed or confined space. However, most dry freight containers have very limited ventilation, with just two small openings on the side walls. The requirement for maintaining a weatherproof interior necessitates that the gaskets around the door prevent water ingress but also reduce ventilation. Additionally, the steel structure of the container absorbs atmospheric heat resulting in higher than ambient interior temperatures. High temperatures, low ventilation and of the cargo characteristics can result in a toxic internal atmosphere.
The development of globalised trade has driven the need for effective and speedy transport of goods. Now, containers - the choice of many shippers - may be packed one week in China, India or South America, and reach their destination within tight transit times to service a just in time stock management culture.
Alongside this, pressures to minimise the movement of pests from one country to another has resulted in an increase in fumigation. Annex 9 to the IMO/ILO/UNECE Code of Practice for packing cargo transport units (CTU Code) describes fumigation as a method of pest control that completely fills an area with gaseous pesticides, or fumigants, to suffocate or poison the pests within - or personnel subsequently entering a container.
"fumigation completely fills an area with gaseous pesticides to suffocate or poison the pests within - or personnel subsequently entering a container"
Efficacy in fumigation
About 15% of the eight million containers handled through the port of Rotterdam during any one year will have been fumigated and by the time the container reaches its destination fumigant gas will have dissipated. However, not all of these fumigated containers needed to be treated. There are reports of containers being routinely filled with fumigants by persons who have knowledge of neither the cargo, nor the properties of the gas. Containers exclusively filled with TV sets have been fumigated as well as containers packed with mattresses, clothes and food.
"There are reports of containers being routinely filled with fumigants by persons who have knowledge of neither the cargo, nor the properties of the gas"
Equally, fumigant cylinders intended to protect the cargo for several weeks may be used even though the transport time may be significantly shorter. The gas development, therefore, may be at its peak when the container arrives to be opened.
Broader cargo risks
Even cargoes that do not require fumigation, for example bulk cargo wood chips, pulp wood and wood pulp pellets may generate a risk to the unpacker. During the transport of such cargoes chemical processes takes place that deplete oxygen and may emit carbon monoxide or carbon dioxide through oxidisation.
Chemicals associated with the manufacture of certain goods, such as furniture and footwear, will also be released over time. If these goods are packed before the high concentrations of these dangerous gases have dissipated - and particularly where the transport time is short - there is a risk to those involved in unpacking the container at the destination.
Practice & compliance
Research carried out in the Netherlands found that 10% of containers had dangerously high concentrations of hazardous or dangerous gases. 2% had been actively fumigated, while the remaining 8% were found with toxic gases associated with the manufacturing process. For example, containers carrying shoes were found to have a number of hazardous gases such as toluene, benzene, 1.2 dichloroethane, methyl bromide and formaldehyde.
The CTU Code echoes the
requirement that containers that have been fumigated are marked with an appropriate label, though the Dutch research also found that significant numbers of containers that had been fumigated carried no label. Containers carrying non-hazardous goods, such as shoes, but found with high concentrations of toxic gases resulting in hazardous internal atmospheres also carried no indication. Legislation in the Netherlands now requires that containers that have been found to carry hazardous gases or non-hazardous goods with hazardous internal atmospheres must be subjected to testing prior to the initial opening of the container doors.
"even after ventilation a container should still be considered as an enclosed space"
Additionally, the CTU Code recommends that before entering a container the doors are opened to allow the internal atmosphere to regularise with the ambient surroundings. However, even after such ventilation a container should still be considered as an enclosed space and personnel remain at risk from residues left within the container when entering. Fumigant packages left in the container after the cargo has been unpacked remain a hazard; should such a package come in contact with water it may generate phosphine gas in large quantities, not only affecting those within the container but also those in the immediate area. Further, hazardous atmospheres within containers generated by the venting of processing chemicals can be transferred to adjacent storage areas.Safe system of workHealth and safety recommendations generally would be that all personnel should avoid entering confined or enclosed spaces. However, in the case of container operations, where such avoidance is impossible, entities need to implement a safe system of working inside.
This should include ensuring that the atmosphere is safe to enter and that the activity is overseen by a supervisor to monitor precautions are taken and to check safety at each stage - and who may remain present during the packing and/or unpacking process.
"ensure that the atmosphere is safe to enter and that the activity is overseen by a supervisor to monitor precautions are taken and to check safety at each stage"
Sadly, incidents recur. All too often, multiple personnel are injured or die. In part, this is due to the natural human response to assist. Don't be a statistic - establish safe working practices, ventilate empty units prior to commencing packing and full units prior to unpacking. Be prepared to test the atmosphere before deploying personnel. Establish, communicate and test an effective rescue procedure.
We gratefully acknowledge the assistance in the preparation of this article of Bill Brassington of ETS Consulting.
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