It is not safeto store osmium in ordinary laboratory plastic containers. Osmium penetrates polyolefin plastics (polyethylene, polypropylene) to some depth, and reacts with them, so containers made from these plastics or of polystyrene or polycarbonate with polyolefin closures are not recommended.

Osmium is usually supplied with some protective packaging and, should further security be desired, I would consider placing the glass ampoules inside polyethylene or polypropylene tubes. This would allow considerable shock protection and, if the ampoule did break, the outer container would protect against leakage for the short time required to get it to a fume cupboard. The same principle can be applied to osmium solutions prepared in glass bottles: enclosure in an outer polyethylene bottle will give shock protection and temporary containment. Also, its blackening indicates how much leakage has occurred from the supposedly closed glass container.

In this regard, we have a rule that osmium solutions are never stored in the laboratory refrigerator.