The European market is demanding that cables used in LANs, WANs, etc. meet LSZH specification. The IEC 60332-1 governs the Flame Retardant Grade specifications in reference to LSZH cables.
Reduction of dangerous/poisonous gases
Essentially, the compound used in manufacturing cables meeting the above specification reduces the amount of dangerous/poisonous gases in case of fire.
The main difference in specifications between IEC 60332-1 versus UL® 1581, UL 1666 and UL 910 is that the cable under the IEC spec can continue to burn while still emitting very low gases. The UL specs demand that the flame be extinguished, but it can still emit dangerous/poisonous gases.
Today virtually all medium and large installations in Europe must meet the IEC specification. Many public authorities are already demanding that new installations must meet IEC 60332-3 which is a more demanding flammability specification for LSZH.