In short, the correct nitrox mix can be safer than air for the diver. However, we need to qualify that; by correct I mean the most appropriate mix for your dive and it’s safer provided you follow the guidelines for its use. There are some additional guidelines to follow (when compared to air) and some priorities have changed. Some of the benefits are listed below, for hyperoxic mixes (i.e. EANx), but it should be noted that some of these are a double edged sword and could also be disadvantages if the guidelines are not followed.

• Longer NDL – because we work to an EAD the NDL for our actual depth on nitrox is the one that applies to our EAD. This will be shallower than our actual depth, thus the NDL will be longer than if we were using air
• Reduced decompression penalty due to the lower level of nitrogen absorbed during the dive. This may be realised by surfacing according to the nitrox tables or as an additional safety factor by following the standard air tables.
• Shorter surface intervals and longer subsequent dives due to the lower residual nitrogen level following a dive. The surface interval is followed for the EAD not the actual depth. Again it may be used as safety padding by following the standard air surface interval.
• Nitrox provides faster off gassing than air during decompression. It may be used to reduce the length of the decompression penalty by following a nitrox decompression schedule, or it may be used as padding to increase the safety factor by following an air decompression schedule. This is similar to the use of pure oxygen during decompression. On the surface it also provides an alternative to pure O2 in situations where it is desirable to breath a mix with a higher O2 percentage than air.
• The reduced level of nitrogen in your system has also been claimed to reduce the feeling of lethargy or tiredness following a dive, this is thought to be due to a reduction in sub clinical DCS i.e. a reduction in the number of asymptomatic bubbles in our system after a dive.