Kathleen Couillard —The Rumor Detector
Agence Science-Presse (www.sciencepresse.qc.ca)
As happens every year, with the cold weather, Canadians head south to Florida and other destinations. Even if it’s the heat that attracts snowbirds, we associate seaside vacations with good health. The Rumor Detector nonetheles notes that the virtues of sea air have been greatly exaggerated.
The Rumor’s Origin
Since the 18th century, coastal regions have been prized for their positive effects on health and their curative properties, even by doctors. In 1938, doctors wrote in the British medical journal The Lancet that their predecessors a century and a half ago praised the “energizing” properties of sea air. A movement promoting the construction of a “convalescent home” on the English seaside coast made its appearance.
Nowadays, it is rather the tourism industry which extols the health benefits of coastal environments, particularly for those with respiratory ailments.
Yet there are few studies that can confirm if there is indeed a link. In 2012, British researchers used the 2001 census to try to answer the question. They noted that the closer someone lived to the coast, the better their reported health was.
In 2019, Belgian scientists carried out the same exercise and concluded that people living within 5 km of the sea said their health was better than those living 50 to 100 km in the interior. A study conducted for other European researchers in 2023 noted that the purported beneficial effects on health were greater for those living within 2 km of the coastline.
Several Factors
According to these scientists, several factors could be at work. For example, the seaside might be more conducive to physical activity, and might also help reduce stress. Nonetheless, it could be that this environment has physical and chemical characteristics that positively influence health.
When waves break on the surface of the ocean or the sea, a shower of fine droplets forms. These droplets are carried away by the wind. This is called sea spray. It transports several salts with it: sodium, magnesium, calcium and potassium. We can detect large quantities of salts in the air within 500 metres of the water’s edge, American researchers explained in 2021. Scientists estimate that this concentration lies within 0.006 and 0.2 micrograms (μg) of salts in every litre of air. Someone spending their day by the sea or ocean would inhale between 60 to 200 μg of sea salts per day.
Still, according to these American researchers (who were investigating the benefits that this could have to battle a respiratory disease like COVID), breathing in salts present in the air could be a good way to improve the hydration of the respiratory tract, and to help clear away mucus.
Cystic Fibrosis
In a 2014 interview with the Wall Street Journal, the American doctor Thomas Ferkol said that many of his patients suffering from cystic fibrosis – a rare disease that attacks the mucous and the respiratory tract – reported feeling better when they were on the coast.
These observations have inspired doctors to come up with an apparatus allowing cystic fibrosis sufferers to inhale a saline solution. According to a 2006 study in the New England Journal of Medicine, the use of this device over the course of one year was associated with a “moderate” improvement in lung function and reductions in the number of acute lung infections and inflammations. This strategy is still recommended, notably in the United States, on the Cystic Fibrosis Foundation website.
Moreover, in their 2021 article, American researchers concluded that high levels of salts in the air, along with high humidity near the sea, may have reduced COVID-19 incidences and deaths in coastal areas of the United States. According to the authors, salty air may reduce droplet production, and therefore transmission of the virus.
When we don’t consider the salt and the water, we often hear that coastal areas have better air quality in general. In their 2019 study, Belgian researchers noted that cities located within 5 km of the coast had less pollution.
Health Risks
Nonetheless, recent data shows that sea air isn’t as healthy as we would like to think it is. Biogenic molecules can be found in sea spray, researcher Emmanuel Van Acker of Belgium’s Ghent University explained in 2019. These molecules, which are produced in the water by bacteria and phytoplankton, contain vitamins, pigments and polyphenols, but also phycotoxins like those produced when algae proliferate. These substances can impact health when inhaled.
In 2022, the National Agency for Food, Environmental and Occupational Health Safety (ANSES) in France warned beachgoers of exposure to toxins produced by sea microalgae when inhaling sea spray. In a review of the subject in 2023, scientists said that 15% of asthma cases in coastal regions may be attributable to these toxins.
Finally, according to a 2024 study by researchers in Stockholm, PFAS – chemical molecules used in several industrial processes and in some consumer products – can be found in coastal regions, since they are present in sea spray. In effect, PFSAs, because they are known to accumulate in the oceans, can be “ejected” into the air.
Verdict
Some characteristics of sea air could favor the hydration of the respiratory tract and improve symptoms with some illnesses, especially respiratory diseases. But over the last few years we’ve discovered that sea air can also contain contaminants that are bad for your health.
Link to the original article: https://www.sciencepresse.qc.ca/actualite/detecteur-rumeurs/2024/11/07/air-marin-bon-pour-sante-respiratoire-incertain
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