Informative Material 10 - Testing CTUs for hazardous gases
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Informative Material 10 - Testing CTUs for hazardous gases

 1 Introduction

1.1 The risk of "hazardous gases in CTUs" is relevant to all companies that handle CTUs, such as distributors, warehouses, wholesalers, transport companies, importers, retailers and manufacturing companies. It includes both acts that fall within the internal business processes (manufacturing), and actions performed on behalf of third parties (service providers and logistics companies).

1.2 Hazardous gases in CTUs can come from:

  • .1 deliberately adding gases to prevent decay and deterioration of the load or CTUs by pests;
  • .2 the evaporation of substances used in the manufacture of products or dunnage;

  • .3 (chemical) processes in the cargo.

1.3 In addition, incidents can occur through leakage of CTUs with hazardous substances. Several substances are often found simultaneously in CTUs.

 2 An example of a possible action plan for checking for hazardous gasesfootnote

2.1 This action plan focuses on employees of companies, involved in opening and unpacking of CTUs. Wherever this action plan refers to 'the company', it refers to the company, not necessarily the ultimate consignee, with responsibility and authorization for opening and unpacking the CTU, which can occur at different points in the supply chain.

2.2 The action plan "Safe handling of gases in CTUs" includes a policy process and an operational process. The policy process indicates how a company can design a policy to deal safely with gases in CTUs. The operational process leads to the "safe" opening and entering of CTUs.

2.3 At the end of the description of the process steps, the activities, the moments of choice and the required information may be presented in flowcharts.

2.4 The action plan consists of the following steps:

  • - the drawing up of a company policy;
  • - taking delivery of CTUs;

  • - measurement survey;

  • - measures;

  • - safe opening and entering of CTUs;

  • - registration.

 3 Possible action plan structure

3.1 Step 1 – Drawing up of a company policy

3.1.1 The company should gather information about the CTU issue and the chain approach. Then an inventory of the CTUs to be received, their cargo and origin should be made. These are referred to as CTU flows. Finally the company should draw up a risk profile for every CTU flow.

3.1.2 Based on this preliminary examination, the CTUs should be assigned to one of the following categories. This category classification determines the further processing of the CTU (flow):

3.1.2.1 Category A: The CTU contains hazardous gases. The gases in question and their expected concentration are known.

A CTU falls into category A if, based on available information, e.g. a previous measurement survey, analysis of the CTU flow and the shipping documents – it has been determined which harmful substances are to be found. In such a case, there is a homogenous CTU flow. Upon receipt of the CTUs, random controls (incl. measurement survey) should be carried out to determine that no changes have occurred in the supply chain.

3.1.2.2 Category B: It is not known if the CTU contains hazardous gases.

A CTU falls into category B if it is not known whether the CTU contains hazardous gases. That would apply for every CTU that is not part of a homogeneous CTU flow and that cannot be shown to belong to category A or C.

3.1.2.3 Category C: The CTU does not contain any hazardous gases.

A CTU falls into category C if the following four conditions are met:

  • - the preliminary examination shows that the container flow cannot contain hazardous substances;
  • - there is a homogenous container flow;

  • - previous measurement research shows that no measurable hazardous gases have been found in this container flow and the data are statistically sound;

  • - upon receipt of the CTUs, random controls (incl. gas measurements) confirm that no changes have occurred in the chain.

Based on the preliminary examination, the company should draw up a company policy regarding container gases, a company procedure and an employee-training programme. Where possible, the company should arrange with other companies that are part of the same logistics chain to limit or manage the risks when opening and entering the CTUs.

The company should periodically evaluate its policy "Safe handling of gases in CTUs". Reasons for adjustment of the policy may include:

  • - (abnormal) readings;
  • - incidents;

  • - changes in current knowledge and legislation;

  • - changed agreements with chain partners.

3.2 Step 2 – Receiving CTUs

A company that receives CTUs should have verified in step 1 to which category a CTU belongs. Once the category has been determined, the CTU should be dealt with according to the corresponding procedure:

  • - Operational Process: category A CTUs;
  • - Operational Process: category B CTUs;

  • - Operational Process: category C CTUs.

The action plan and the procedures described in the operational process should not distinguish between different origins of the hazardous substances that are present.

3.3 Step 3 – Measurement survey

3.3.1 A gas measurement expert should set up a measuring strategy and carry out the measurement survey. The company may outsources the measurement. The gas measurement expert should be properly trained and keep his or her knowledge and skills up to date. The gas measurement expert should record the measurement results, the findings (in relation to the acceptable limitfootnote) and the recommendations in a measurement report. The recommendations should focus on:

  • - release of CTU, with or without conditionsfootnote;
  • - ventilation / degassing of the CTU.

3.3.1.1 Category A CTUs:

The first consideration should be to check whether a limited or an extensive measurement survey should take place. In a limited survey only the hazardous substances are measured on the basis of a previous measurement survey. However, the company should be able to demonstrate its assumptions. If the assumptions are not correct, the CTU flow should no longer belong to category A, but to category B.

For a category A CTU, based on available data, it may be decided to carry out the measurement before or after ventilation.

The reading can lead to the following findings:

  • - The expected gases are not detected. Based on the preliminary examination, it should be assessed whether the classification in category A is correct;
  • - The expected gases are detected and the concentrations are below the limits. The concentration further within the CTU may be higher. A gas measurement expert should advise the company whether the CTU may be released or what additional measures, if any, should be taken (via step 4 to 5 described below);

  • - The expected gases are detected and the concentrations exceed the limits. The CTU should not be entered. Additional measures should be applied (via step 4 to 5 described below).

3.3.1.2 Category B CTUs:

A measurement survey should always be carried out on a CTU of category B. The reading may lead to the following findings:

  • - No gases are detected. The CTU may be released and may be opened and entered (via step 5 below);
  • - Gases are detected but the concentrations are below the limits. The concentration further within the CTU may be higher. A gas measurement expert should advise the company on whether the CTU may be released or what additional measures, if any, should be taken (via steps 4 and 5 below);

  • - The expected gases are detected and the concentrations exceed the limits. The CTU should not be entered. Additional measures should be applied (via step 4 to 5 described below).

3.3.1.3 Category C CTUs:

It is highly unlikely that the CTU from category C contains hazardous gases. However, the company should demonstrate this by randomly carrying out a measurement. If the spot check shows that the assumptions are correct, the procedure for a category C container is followed (step 5 below). If the assumptions are not correct, the container flow no longer belongs to category C but to category B.

3.4 Step 4 – Measures

3.4.1 The company should take measures based on the results of step 3. Examples of such measures are:

  • - ventilation followed by new measurements;
  • - the removal of fumigant residues by trained personnel wearing appropriate personal protective equipment;

  • - unpacking by a specialized company.

3.5 Step 5 – Safe opening and entering of CTUs

3.5.1 The company may release the CTU and it may be opened and entered if:

  • .1 previous research shows the CTU is safe to enter (category C);
  • .2 the gas measurement expert indicates in his recommendations that employees can safely open and enter the CTU (category A, B and C (spot check)); and

  • .3 the history and knowledge of the CTU flow corresponds with the measurement results and the recommendations of the gas measurement expert (category A and C (spot check));

3.5.2 If a company releases a CTU, it should be able to demonstrate that it has done so on the basis of a documented action plan. At this stage, the company also should decide, after the gas measurement expert has submitted a recommendation, whether additional measures are needed during the unpacking process. The CTU may then be released subject to conditions defined by the expert.

3.5.3 The company should also carry out repeat measurements if the following situations have arisen or may arise:

  • .1 intentionally fumigated CTUs where residues of pesticides or herbicides, such as magnesium or aluminium phosphide powder, are still present in the CTU;
  • .2 if measurements taken through the door gaskets indicate the presence of hazardous substances at concentrations below the permissible limit(s). Practical experience has shown that, in such cases, the concentration inside the CTU can be higher;

  • .3 if there is a possibility that the gas may concentrate beneath and/or inside the packages and may be released at a later stage;

  • .4 if the CTU consists of more than one compartment;

  • .5 if there is a possibility that a hazardous substance will be released as a result of damage to the packaging;

  • .6 if a gas may evolve from the goods;

  • .7 if the nature of the goods is such that it is difficult or impossible to degas them; and

  • .8 if the gas measurement expert submits a recommendation to that effect.

3.5.4 Whenever a dangerous work situation arises all personnel should be withdrawn, the CTU closed and the adjacent area cordoned off. The company should determine the next steps which could be (see step 4):

.1 (Renewed) Ventilation/degassing of the CTU;

.2 Have the CTU unpacked by a specialized company. This can be at a specifically designed degassing location and/or unloading by specialized personnel; and

.3 Continuous measuring during unloading and if necessary active ventilation.

3.6 Step 6 – Registration

3.6.1 The company should retain the data collected. These are:

  • .1 registration of container flows and assignment to categories;
  • .2 measurement records; and

  • .3 measures taken.


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