For a dive planned at 40 meters, what is the NDL according to IANTD air dive tables?

For a dive planned at 40 meters, the no-decompression limit (NDL) is determined based on the amount of nitrogen that can be safely absorbed by the body without increasing the risk of decompression sickness upon ascent. According to IANTD guidelines and air dive tables, the NDL at this depth is established considering various factors like depth, time, and the physiological effects of nitrogen uptake.

In this case, the NDL of 15 minutes at 40 meters indicates that divers can spend up to that duration at this depth without needing to perform decompression stops during their ascent. Spending more time at this depth than the NDL would necessitate compliance with specific ascent protocols to mitigate the risk of decompression illness.

The other options reflect longer times that exceed the established NDL for this depth, which would not be safe according to the IANTD air dive tables. Thus, the value of 15 minutes is correctly supported by the IANTD guidelines for safe diving practices at the planned depth.