Many of us have experienced a familiar feeling of longing that comes on the very last day of a vacation, wondering if it really would hurt to experience just one more dive along a house reef or whether we might be able to get in one more trip to that wreck that’s managed to hold our attention for the last few dives. When should you stop diving? One day before flying? Two days, to be safe?
Reducing the Risk of Decompression Sickness
A commercial airliner carries passengers to great heights, and despite cabin pressure equalization, it exposes us to the pressure equivalent of an altitude of about 8,000 feet. Ascending to altitude shortly after diving increases the risk of DCS greatly; this happens due to the tendency for bubbles to form inside our tissues when gases remaining from diving have not completely worked their way out of the body’s systems, and it works in the same way an uncontrolled ascent from depth does.
To illustrate the risks, consider the results from sixteen cases of DCS that occurred during or after flights, which were analyzed by the Divers Alert Network (DAN). Two people developed their symptoms three days after flying home from dive vacations. The rest occurred when divers had flown just two to seven hours after diving.
Experimental studies conducted on animal subjects in the past have shown that exposure to altitude after diving increases not only the chances that DCS will occur, it also increases the severity of the illness. The results of these tests indicate that a dive to the no deco limit, followed by a flight between 6-8 hours later might be adequate, while further analysis has shown that waiting at least 12 hours is better.
Experts also warn that the amount of time between diving and flying should be extended if diving is extreme, or if you’ve been making a few dives daily while on vacation, since more nitrogen accumulates in the body’s tissues under these circumstances. Bubbles that might be present from a previous dive may cause you no pain or other problems at sea level, but could cause DCS as they expand at altitude.
Every year, almost half a million people fly sometime between 12 and 24 hours after diving, with incidences of DCS being recorded at a minuscule 0.004%. The current recommendations for flying are as follows:
- Divers who have had less than two hours total no-deco dive time should wait 12 hours.
- Divers who do multi-day diving need to wait between 18 and 24 hours before flying.
- Minimize risk by reducing diving exposure overall on the last two days before flying
By following a conservative schedule, you can minimize your risk of developing Decompression Sickness at the end of your vacation. Doctors recommend diving no more than three times per day throughout the vacation. Spend time snorkeling if you’re feeling tempted to dive during those last hours, or find a topside attraction to occupy your time; coming home to a case of DCS is not worth the risk.