Deep Dive: An Interview with Dr Hanna Van Waart

Episode Notes Research, CPSC Warning, and Manufacturer Responsibility Hanna Van Waart PhD  Exercise Physiologist at the University of Aukland discussed full face mask safety, her research and manufacturer’s responsibility The research article, “Full-face snorkel masks increase the incidence of hypoxemia and hypercapnia during simulated snorkeling compared to conventional snorkels,” was published in Diving and Hyperbaric Medicine in December 2023. The study was led by Janneke Grundemann, with coauthors Xavier C.E. Vrijdag, Nicole Y.E. Wong, Nicholas Gant, Simon J. Mitchell, and Hanna van Waart. Hanna van Waart is affiliated with the Department of Anesthesiology at the University of Auckland. The research team examined whether full-face snorkel masks increase the risk of rebreathing, elevated carbon dioxide, and reduced oxygen levels compared with a conventional snorkel. In the controlled study, 20 healthy participants used two different full-face snorkel masks and a conventional snorkel under seated, light-exercise, and moderate-exercise conditions. The researchers found that full-face snorkel mask trials were stopped more often because end-tidal carbon dioxide exceeded the safety threshold. During light exercise, 18 of 40 full-face mask trials were stopped compared with 4 of 20 conventional snorkel trials. During moderate exercise, 9 of 22 full-face mask trials were stopped compared with 3 of 16 conventional snorkel trials.  The main concern identified by the study is rebreathing caused by non-unidirectional airflow. Full-face snorkel masks are designed to separate inhaled and exhaled air, but the researchers found evidence that this separation was not consistently maintained. Carbon dioxide and oxygen levels in the eye pockets of the masks fluctuated in a way that showed rebreathing in all full-face mask wearers. This means users may rebreathe exhaled air, leading to hypercapnia, which is elevated carbon dioxide, and hypoxemia, which is reduced oxygen in the blood. Traditional snorkels also carry some risk of carbon dioxide buildup, but they allow users to clear the snorkel tube, remove the mouthpiece, or take fresh breaths more easily. Full-face snorkel masks can be harder to remove and may delay access to fresh air, especially if a person is tired, panicked, or already experiencing symptoms from rising carbon dioxide. Because concerning findings occurred in healthy adults, the risk may be greater for children, older adults, and people with underlying heart or lung conditions. There are also fitting issue. Not everyone has the same face, and smaller faces may have worse fit and there is also the factor of individual lung capacity. These research concerns are reinforced by recent action from the U.S. Consumer Product Safety Commission. In 2026, the CPSC warned consumers to stop using OUSPT full-face snorkel masks immediately because of the risk of serious injury and death from drowning. The CPSC stated that the mask can cause labored breathing, loss of consciousness, excess fluid in the lungs, and increased carbon dioxide levels that can worsen breathing difficulty. The agency also reported five consumer incidents involving trouble breathing, lightheadedness, or loss of consciousness, as well as one lawsuit alleging that the product caused a drowning fatality. Approximately 84,000 OUSPT masks were sold on Amazon between March 2019 and February 2026, and consumers were advised to stop using and dispose of the masks rather than sell or give them away. Taken together, the Diving and Hyperbaric Medicine study and the CPSC warning support a stronger safety message: full-face snorkel masks should not be treated simply as recreational toys. They function as breathing apparatuses because they control how a person inhales and exhales while face-down in the water. For that reason, manufacturers should carry the responsibility to prove these products are safe through rigorous design testing, independent evaluation, and appropriate regulatory standards before they are marketed broadly to residents, visitors, families, and children. The practical safety message is that snorkelers should use simple, well-fitted equipment, snorkel with a buddy, take regular fresh-air breaks, and avoid full-face snorkel masks, especially for children, older adults, and people with medical risk factors. References: Grundemann J, Vrijdag XCE, Wong NYE, Gant N, Mitchell SJ, van Waart H. Full-face snorkel masks increase the incidence of hypoxemia and hypercapnia during simulated snorkeling compared to conventional snorkels. Diving and Hyperbaric Medicine. 2023;53(4):313-320. doi:10.28920/dhm53.4.313-320. U.S. Consumer Product Safety Commission. CPSC Warns Consumers to Stop Using OUSPT Full-Face Snorkel Masks Immediately Due to Risk of Serious Injury and Death from Drowning Hazard. 2026. ** Support Deep Dive Into Water Safety by contributing to their tip jar: https://tips.pinecast.com/jar/deep-dive-into-water-safety