While the PDC's calculations are based on current decompression research and technology, it is important to realize that the PDC cannot monitor the actual physiological functions of an individual diver. All decompression schedules currently known to the authors, including the U.S. Navy tables, are based on theoretical mathematical models that are intended to serve as a guide to reduce the probability of DCI.
Diving with nitrox may provide you with an opportunity to increase bottom times or possibly reduce the risk of DCI by reducing the nitrogen content in the gas mix. This requires specialized training that is not covered in this program.
Freediving, in combination with scuba diving, may present risks that have not been researched and are not commonly known. It is recommended to wait a minimum of 24 hours after scuba diving before freediving.