Fumigation Gas Risk When Opening Containers

Fumigation gas risk: what builds up behind the closed door?

A container that has travelled for weeks from a distant port to your warehouse is a closed box until the moment it is opened. Two types of gas can build up inside. The first is fumigants: toxic gases used to rid the cargo or wooden packaging of insects and pests. The second is product-derived gases: formaldehyde and solvent vapours released over time from furniture, textiles, footwear, plastics and electronics. With live produce such as fresh fruit and vegetables, oxygen may also be depleted.

Fumigation gas risk is these gases hitting the unloading team in the face when the container door is opened, or being released gradually while the cargo is unloaded. Symptoms start with headache, dizziness, nausea, chest tightness and shortness of breath; with some fumigants the effect may worsen hours later. Port, bonded warehouse, free zone and import warehouse employees are the first to face this risk. For warehouses around the Gemlik ports and the free zone in Bursa, and for importers in the region, the issue is directly relevant.

Which gases, and where do they come from?

The limit values are taken from Annex 1 of the Regulation on Health and Safety Measures for Working with Chemical Substances. For how to read the table, see our article on occupational exposure limit values.

The four-gas detector commonly used in confined spaces (oxygen, flammable gas, carbon monoxide, hydrogen sulphide) does not measure fumigants reliably. A "clear" reading on this instrument does not mean the container is safe; read our article on confined space gas testing for the limitations of detectors.

How can you tell a container has been fumigated?

The IMDG Code applied in international maritime transport requires a fumigation warning sign to be placed on the door of fumigated cargo transport units, where anyone trying to enter will easily see it. The sign shows the name of the fumigant used and the date and time of application; if the container has been ventilated, the ventilation date is also written on the sign. Fumigated units are referred to in these rules by the number UN 3359.

Before opening the door, look for these signs:

1. Is there a fumigation warning sign on the door? Can the fumigant name and date be read?
2. Is there a fumigation note in the transport documents, the bill of lading or the fumigation certificate?
3. Do the wooden pallets bear an "MB" stamp showing treatment with methyl bromide?
4. Are there tablets, sachets or powder residues visible through the gap in the door?

Import container gas measurement: before opening the door

Opening a container door is like opening the hatch of a confined space. The following sequence should be turned into a written instruction in the risk assessment:

1. Document check: If there is a fumigation note or warning sign, the cargo is treated as "fumigated" and is not opened until the measurement result is known.
2. Location: If possible, the container is opened in an open, windy place away from the warehouse door and work areas.
3. Measurement before opening: Measurement is made without opening the door, using a sampling hose inserted through the gap in the door seal or between the door locks. It is carried out by a person trained for this work, with an instrument suitable for the gas concerned and with valid calibration.
4. If the result is not safe: The door is not opened, the area is cordoned off, and the importer and, if necessary, an authorised fumigation company are informed.
5. If the door is to be opened: The doors are opened with the wind at the back, the person opening them moves away immediately and no one waits at the doorway.

How is the container ventilation period determined?

There is no fixed period in the legislation of "ventilate for this many minutes", nor can there be, because the time needed varies with the type of gas, the type of cargo, the temperature and how full the container is. The correct approach is the ventilate, measure, decide cycle:

• Natural ventilation: The doors are left open and the area is cordoned off. If fans or portable ventilation are used, the gas is directed into the open air, not into the work area.
• Repeat measurement: At the end of the set waiting time, measurements are taken at different points: at the doorway, at the top of the cargo and with a hose inserted into the cargo. If the values are not below the safe level, ventilation continues.
• Absorbent cargoes: Cargoes such as cardboard, textiles, foam and grain absorb gas and release it slowly. A clean measurement at the doorway does not show that no gas remains deep within the cargo. For these cargoes, measurement is repeated throughout unloading.
• Records: Measurement times, values and the person making the decision are written down. For a gas without a limit value in Annex 1, the target is agreed in advance with the workplace physician and the OHS specialist.

The approach is the same in official quarantine fumigations: Art. 12 of the Plant Quarantine Fumigation Regulation requires it to be established by measurement at the end of the fumigation period whether the space has been adequately ventilated and suitable working conditions for staff have been achieved.

Entering and unloading the container

Even if measurement shows a safe level, the inside of a container is a space with limited ventilation. Therefore:

• The person entering, or the forklift operator, carries a personal detector that measures the gas concerned; if unloading takes a long time, measurement is repeated at intervals.
• No one works alone at the far end of the container; someone outside can see them.
• Anyone feeling headache, nausea, dizziness or shortness of breath leaves immediately, is taken into fresh air and 112 is called. In suspected poisoning, information can be obtained from the 114 National Poison Information Centre. Information on which gas was used is given to the medical team.
• Fumigant tablet and sachet residues are not touched with bare hands; collecting them is the fumigation company's job.
• A filter mask is not a safe solution when the type and concentration of the gas are unknown. For some fumigants there is no suitable filter or the filter's life is short; for selection, see our article on gas mask filter colour codes, but give priority to ventilation and measurement.

For the general rules of working inside containers, read our article on working in confined spaces.

Responsibility at ports, bonded warehouses and warehouses

Art. 24 of the Regulation on the Carriage of Dangerous Goods by Sea and Loading Safety gives the administration the power to make arrangements, taking IMO legislation into account, on gas measurement, degassing and entry into enclosed spaces for fumigated cargo transport units at coastal facilities and on ships. However, once the container leaves the port and arrives at your warehouse, the safety of your employee who opens the door is your responsibility: under Art. 4 and 10 of Law No. 6331, this work is included in the risk assessment, an instruction is written and employees are trained.

The minimum arrangement for an importing warehouse is: a written container opening instruction, a suitable gas measuring instrument and at least one person who knows how to use it, a designated opening area, requesting fumigation information from the supplier, and writing what to do in an incident into the emergency plan. For other risks around the port, see our article on forklifts and cranes at the Gemlik ports, and for warehouses with heavy container traffic, our article on OHS in e-commerce warehouses.

We prepare the container opening instruction and measurement arrangement for import warehouses as part of the risk assessment and monitor implementation on site through our OHS specialist service. We plan workplace atmosphere measurements with accredited laboratories. For other sector-specific topics, see our logistics and warehousing sector page, and for the penalties for breaching measurement and inspection obligations, our OHS administrative fines tool.

Frequently Asked Questions

How long should a fumigated container be ventilated?

There is no fixed period. The doors are opened and the container is ventilated, then measured again at different points. Ventilation continues until measurement shows a safe level; for cargoes that absorb gas, measurement is also repeated during unloading.

Is measurement needed if there is no warning sign on the container?

Yes. The sign may have been forgotten or removed, and no sign is applied for product-derived gases. For high-risk product groups and cargoes with unclear fumigation information, measurement must be made before the door is opened.

Does a four-gas detector measure fumigation gas?

Not reliably. Oxygen, flammable gas, carbon monoxide and hydrogen sulphide sensors are not designed for phosphine, methyl bromide or sulfuryl fluoride. A gas-specific sensor or colour-change tube is used.

What should be done for an employee who collapses inside a container?

The rescuer does not enter without protection. If possible, the employee is talked out by calling from outside; rescue requires measurement and suitable respiratory protection. 112 is called and the name of the gas used is given to the medical team.