Researchers probe for answers to snorkel-related fatalities
Maui had more deaths than other islands from 2009-2018
WAILUKU — Health officials and researchers behind a recent study that could link a pulmonary condition to snorkel-related deaths are trying to learn more about the causes behind the fatalities, especially in Maui, which has seen more drownings than other islands.
“There were more fatal and nonfatal drownings from snorkeling in Maui than any other island, by large margins,” state Department of Health epidemiologist Daniel Galanis said via email, referencing statistics from 2009-2018. “This was surprising to me, as Maui has only around 60 percent of the visitor days as Oahu, over the same period of time.”
Preliminary data from a study released last week suggested that oxygen deprivation induced by rapid onset pulmonary edema, known as ROPE, is the most probable cause of snorkel-related fatal and near-fatal drownings.
Drowning by ROPE is different in that a person doesn’t necessarily have to be inhaling water. It’s a sudden respiratory issue that can be triggered by snorkeling, a phenomenon that wasn’t previously studied with this water activity, according to The Snorkel Study: Mysterious Snorkel Drownings Explained.
“Snorkeling isn’t the low-risk activity everyone thinks it is,” said program manager Carol Wilcox in a news release. “Roughly an equal number of residents and visitors drown each year in Hawaii’s oceans, however the vast majority of visitor drownings are while snorkeling, yet very few residents drown while snorkeling. Why is that?”
In October 2017, the state Department of Health established the Snorkel Safety Subcommittee to address public concern about snorkel-related drownings.
The study is asking Hawaii residents and visitors to complete a survey to further determine the causes and risk factors associated with snorkel-related fatal and non-fatal ocean drownings in the state.
DOH’s Emergency and Injury Prevention System Branch reported a total of 93 fatal ocean drownings in 2019 statewide, including 37 residents and 56 visitors. Of those, 21 were in Maui waters.
“It’s important to snorkel with a buddy so that if you get into trouble, your buddy can assist you to shore,” said retired battalion chief of Ocean Safety Colin Yamamoto, also an active member of the Hawaii Drowning and Aquatic Injury Prevention Advisory Committee and a member of the Snorkel Safety Subcommittee. “A lot of times with people who drown, they were by themselves.”
The DOH projects that non-resident deaths in 2020 will be 50 percent less due to decreased travel and foot traffic at the beaches amid the pandemic, while resident deaths are projected to see only a slight decline.
From 2010 to 2019, Maui County accounted for 27 percent (203) of the state’s fatal ocean drownings, which is more than Hawaii Island (114) and Kauai (78) combined.
According to the DOH, snorkeling remains the leading activity for ocean drownings from 2010 to 2019 at 216 total — 197 visitors and 19 residents. During the same timeframe, a total of 152 people drowned while swimming, 117 during an unknown activity and 49 while freediving, which is much more common among Hawaii residents (about 92 percent).
Galanis said that one theory as to why Maui has had more snorkel-related drownings is that the island has more oceanfront resorts by beaches that are more accessible for snorkeling, and snorkeling “appears to be a more common tourist activity” than other islands, which increases the probability of incidents, he said.
“We don’t have data to directly assess the risk of snorkeling, but we know from (Hawaii Tourism Authority) data that 49 percent of visitors reported they engaged in the activity in 2019, while snorkelers comprised 59 percent of the victims of fatal drownings from 2015-2019,” he added.
Galanis explained how the physical demands of snorkeling, including breathing through a constricted tube and swimming for extended periods, might be “underappreciated.”
“Snorkeling is also a relatively accessible activity — low cost and readily available equipment — that many visitors may have little or dated experience with,” he said.
The Snorkel Safety Study by Wilcox, principal investigator Philip Foti and project administrator Ralph Goto used a snorkel airway resistance analyzer, which found that a narrow tube creates more resistance when breathing, and that if the resistance is strong enough and long lasting, it will result in reduced pressure in the lungs, which can lead to ROPE.
With ROPE, snorkelers can oftentimes lose consciousness and strength, a condition that has been associated with scuba diving, but not yet with traditional snorkeling.
“This unravels the mystery of previously inexplicable snorkel-related drownings. It is an important discovery with significant implications,” the report said.
The study researched why snorkelers might get ROPE more than everyday swimmers or surfers by looking into “prone immersion,” or water pressure exerted on the chest, and the breathing resistance created from the snorkel tube and mask.
Forty-nine snorkels were tested, including four full-face masks. Snorkel design ranges from a simple tube attached to goggles to those with purging valves, pinched tubes and full-face coverage.
In general, the simpler the snorkel the less resistance it generated, according to the study.
High resistance adds to the risk of developing ROPE, and the “more you exert, the greater the resistance.”
The Snorkel Study survey was first posted in January 2019, and a small sample of 36 people completed the survey by March 2020. All were Hawaii residents under the age of 55 who are strong swimmers and experienced snorkelers.
“Thus, the survey currently does not shed any light about why visitors seem especially vulnerable,” the report states. “It does show that drownings happen to even the most experienced of watermen and women.”
Of the 36 respondents, 60 percent had symptoms consistent with ROPE-induced hypoxia, 13 percent drifted away from safety, 11 percent reported panic and 8 percent cited ocean conditions.
Only one person reported possible aspiration and 66 percent of respondents were using full-face masks, of which 83 percent felt the full mask contributed to their problems.
Other factors that can increase the risk of ROPE include having an underlying health condition, being a male 50 years old or older or not having ocean experience.
Another theory that will require further research is the idea that exposure to high altitude via air travel is a risk factor for ROPE. Almost all visitors who travel to Maui have recently spent at least five hours on an airplane in cabin pressure thousands of feet in the air.
When looking at full-face masks, the report noted that they pose “no advantage or disadvantage” in terms of resistance compared to other masks. However, based on evaluation of design and feedback from users, it was determined that full-face masks cannot be removed easily in urgent situations even with quick release features, and that a snorkeler can’t remove a mouthpiece like the traditional snorkel. There’s also a possibility for valve malfunction.
In Wailuku on Wednesday, Yamamoto, who was also involved with the recent snorkel research, presented data from a separate “amateur study” of carbon dioxide buildup and his opinion on the the dangers of breathing in exhaled air that remains in the mask or snorkel tube.
After testing 15 different models of traditional and full-face snorkel masks while at rest and jogging on a treadmill, he and other members of the Hawaii Drowning and Aquatic Injury Prevention Advisory Committee found that oxygen and carbon dioxide levels border between normal and “unsafe conditions.”
Depending on the design of the mask and the fitness level of the snorkeler, he said roughly 40 percent of each breath is full of exhaled air.
“No matter what, you will breathe in your own air, traditional or full-face,” he said. “Because you’re rebreathing your own air, which is low oxygen, high carbon dioxide, and if you have preexisting conditions, it may exacerbate those conditions, which may or may not lead to trouble in the water or some type of cardiac event in the water.”
The former 30-year fireman noted the nation’s Occupational Safety and Health Administration, which states that oxygen levels below 19.5 percent are deemed oxygen-deficient and “immediately dangerous to life or health.”
While wearing the snorkel gear in his experiment using sensors, oxygen levels were on average around 18 percent for a traditional mask and an average of 16 percent for an undisclosed model of the full-face mask.
When snorkeling, Yamamoto recommends taking bigger breaths.
“Bigger breaths means more fresh ambient air inhaled,” he said.
If using a full-face mask, Yamamoto recommended that snorkelers do not exert themselves, that they use the mask for surface breathing only, take occasional breaks and practice removing full-face mask in case a situation occurs.
While there are industry standards for scuba and diving equipment, there are limited standards for snorkel equipment, Yamamoto said, which is why he believes snorkelers should choose a mask carefully.
He continues to advocate for more caution labels and ocean safety education on the products and at beaches. And, because Yamamoto experimented outside the water, he hopes independent labs will conduct more in-depth, professional studies in the future.
While data is important for records and determining legislation, Yamamoto reminds everyone to not lose the “human emotion.”
“Each number represents a person who drowns, but they are also a father/mother, cousin, aunty, uncle, husband/wife, friend to someone,” he said. “They have a name. And that’s what the numbers don’t tell us.”
Anyone who has had trouble while snorkeling, or been with someone who has, is encouraged to fill out the Snorkel Study survey at http://www.snorkelsafetystudy .com/. More information about the preliminary report is also available on the website.
Experienced and recreational snorkelers can also observe the following safety tips:
• Always swim with a partner.
• If you can’t swim, don’t snorkel.
• Take occasional breaks.
• Be aware of ocean conditions, and if in doubt, don’t go out.
• Choose snorkel gear thoughtfully.
• Practice using snorkel gear before entering the ocean or trying more complex equipment.
• If you have shortness of breath, don’t panic; stand up, remove snorkel and get out of water.
• Beware of drifting away.
• Swim at a guarded beach.
* Dakota Grossman can be reached at email@example.com.