Oxygen depletion: Sea transportation of bulk cargoes of an organic nature such as wood, paper pulp and agricultural products may result in rapid and severe oxygen depletion and formation of carbon dioxide. Thus apparently harmless cargoes may create potentially life threatening conditions. The cargo holds and communicating spaces in bulk carriers are examples of confined spaces where such toxic atmospheres may develop. Several fatal accidents can occur when people enter unventilated spaces. The IMSBC code lists the following cargoes as potentially oxygen depleting: coal, direct reduced iron, sponge iron, sulphide concentrates, ammonium nitrate based fertilisers, linted cotton seed. Various gaseous products are formed including carbon monoxide, carbon dioxide, hydrogen sulphide and hydro carbons. Entry of personnel into enclosed spaces should be permitted only when adequate ventilation and testing of the atmosphere is done with appropriate instruments. Emergency entry may be undertaken with SCBA. Some cargoes also use up oxygen within the cargo space. The main examples are rusting of steel swarf cargoes. Some grain cargoes may also deplete the oxygen content in the cargo space.