Introductory study: medical monitoring and safety of underwater workers
How does breathing a gas mixture with increased partial oxygen pressure affect the health of underwater workers? With this question in mind, Melissa Vermeulen, occupational health physician at Mensura, decided to observe these divers in action. The findings of the study could make a crucial difference not only for the health and safety of professional divers but also in other fields, such as the construction industry.
Seventeen divers took part in the research study, which was held at the Transfo dive centre in Zwevegem in West Flanders at the end of 2015. The day was filled with scientific studies, with all aspects of health and safety meticulously monitored.
The divers had to breathe an air mixture heavily enriched with oxygen (65% oxygen) for two hours while at a depth of 15 meters. Their blood levels and vital lung capacity were measured before and after the test. Samples were also taken from the air exhaled by the divers.
Targeted health monitoring
One of the main objectives of the study was to identify the volatile organic compounds (VOCs) that are released when breathing a gas mixture with high partial oxygen pressure (e.g. from dive tanks) within a hyperbaric environment. If we can accurately identify those VOCs, then we will be able to detect oxidative lung damage at a much earlier stage.
This will pave the way for targeted, personalised health monitoring for workers in several different industries, including underwater divers who perform tasks such as inspections, repairs, welding or painting in the shipping or civil engineering industry and any other underwater works in close partnership with their surface support team.
Safety standards questioned
In addition to the benefits in terms of medical monitoring, research studies such as this one by Melissa contribute greatly to the prevention of incidents.
Breathing a gas mixture with high partial oxygen pressure can lead to many symptoms: muscle spasms and convulsions, nausea and dizziness, breathing problems and issues with the eyes and ears. To guarantee the safety of the divers, the CNS percentage – which calculates the effect of oxygen toxicity on the central nervous system – is limited to 80% for open water diving or diving in an uncontrolled environment.
To calculate the CNS percentage, dive computers and software use an algorithm based on figures and tables supplied by NOAA, the U.S.-based National Oceanic and Atmospheric Administration. However, whether or not these exposure limit values are adequate or need further reviewing is a question that is yet to be answered.
To be continued
Dr. Pieter-Jan van Ooij, head of the medical diving centre in Den Helder and co-director of the research study, had previously conducted a similar study among divers of the Dutch marine corps. Although all participating divers emerged from the water with no health issues, neither study has provided conclusive results thus far.
Ongoing research is therefore required if we want to finetune the safe exposure limits and provide the best protection possible for professional underwater workers.