New pre-ventilation techniques to eliminate hazardous chemicals in container air

In our research at Karolinska Institutet, we have found that one out of eight shipping containers arriving in Sweden had high levels of hazardous chemicals (exceeding the Swedish occupational exposure limit), including carcinogens, in the air. Most of these chemicals are emitted from the transported goods. As these containers are very tight the chemicals tend to accumulate in the air during transport, and more so at high temperatures. Some containers may also have residues of fumigants (e.g. phospine or sulfuryl fluoride) used for pest control. These chemicals constitute a significant health risk for people entering e.g. during customs inspection or unstuffing at distribution centers. Based on our findings, we developed techniques and specially designed equipment to pre-ventilate containers by two methods. (Method 1) A “suction plate” (patented, design protected) is mounted over one of the corner vents found near the ceiling on all ISO containers. The vacuum created by an extraction turbine keeps the plate firmly attached to the container wall and at the same time draws contaminated container air through the vent at a flow of approximately 140 m3/h. The chemical vapors are reduced by around 90% in one hour. Method 1 allows pre-ventilation without breaking the seal of the container. (Method 2) The container door is opened a few centimeters, a “door nozzle” (design protected) is inserted and the door is closed again. The same turbine as in method 1 is used,. Method 2 requires less equipment, is easier to handle, and allows a higher air flow (240 m3/h), compared to method 1. Regardless of method used, it is important to continue the ventilation until the doors are opened, otherwise the chemicals will reaccumulate in the container air. In conclusion, people should not enter an unventilated container as this means a health risk that can easily be avoided by pre-ventilation. The transport chain logistics is minimally disturbed as only one hour is required. Meanwhile, most companies and employees are unaware of both the risk and how to avoid it.