Dangers of deliberate cold exposure
Part 2: Risks related to cold water immersion
This post is an excerpt from my upcoming book ‘Uncommon Cold: The Science & Practice of Deliberate Cold Exposure.’ The book blends the experiences of my midlife crises with the science of ice baths.
Remember that nothing in this book constitutes medical advice. Consult with your medical professional about the risks and benefits of deliberate cold exposure that may apply to you.
Are ice baths dangerous?
Investigative journalist Scott Carney has documented more than a dozen deaths associated with (mal)practice of the Wim Hof Method (Carney 2023). Although Carney credits Hof's training for giving him "superhuman levels of endurance" and helping to "quiet a persistent autoimmune illness," Carney also cautions that combining Hof's hyperventilation techniques with cold water swimming can result in shallow water blackout -- a condition that causes underwater loss of consciousness and drowning.
Carney is careful to point out that neither hyperventilation nor cold water immersion are particularly dangerous when practiced separately. They only become dangers when they are combined.
Hyperventilation purges the body of carbon dioxide. Because it is accumulation of carbon dioxide in the bloodstream (not a deficit of oxygen) that creates the urge to breathe, swimmers who hyperventilate prior to their plunge may not feel that urge before they lose consciousness from lack of oxygen.
The drownings Carney has documented are all preceded by passing out. To minimize the risks of the Wim Hof Method, both Carney and written instructions on the Wim Hof website caution practitioners that they should never practice hyperventilation or breath holds while in the water.
Nevertheless, in videos and tutorials Hof has sometimes encouraged his trainees to continue their hyperventilation breathing while in the water, creating the possibility of a deadly combination of otherwise beneficial prcatices.
Real risks of ice baths
There are four categories of risks to whole-body, cold-water immersion. University of Portsmouth (UK) Professor Mike Tipton lists the first three as:
drowning,
hypothermia, and
cardiac arrest in his paper called 'Cold water immersion: Kill or Cure?' (Tipton et al. 2017).
I’ll add to two more, which I call 4) operating during rewarm, and 5) shallow water blackout.
Drowning
When water is inhaled into the lungs, suffocating the victim, the cause of death is drowning. Swimming in pools, oceans, lakes, rivers, and streams is inherently dangerous, regardless of the water temperature. For example, although I could not find a single study or documented case of drowning in an ice bath, there is a phenomenon in Japan called 'Dead in Hot Bathtub' (Satoh et al. 2013).
Moreover, drownings sometimes occur at home in bath tubs – especially when sedatives, alcohol, or other drugs that can cause loss of consciousness are involved (e.g., Peden et al. 2019, Okuda et al. 2015). Young children can also be at risk during bathes (e.g., Orlowski 1987).
This suggests two things:
1) ice bath sober, and
2) supervise children in the ice bath .
Hypothermia
The deaths Carney has documented have not resulted from the cold exposure itself, but from loss of consciousness in the water. When most people think of the dangers of cold itself, the first thing that comes to mind is hypothermia.
In her book The Upside of Stress (2012, p186), Stanford Professor Kelly McGonigal claims that "Below five degrees, water becomes so painfully cold that it feels like it is burning your skin. If you were to immerse your whole body in water this cold, it would kill you in less than a minute."
Well, the world record for whole-body cold immersion is 150 minutes. While Hof is most famous for popularizing cold exposure and he used to be the record-holder, the an Austrian man named Josef Koeberl set the new standard.
Given McGonigal's claims, and the fact that Wikipedia claims that the shock of the cold water could lead to "sudden death," daredevils like Koeberl and Hof might cause us to question how they could survive such prolonged exposures.
Given that Wikipedia claims that the shock of the cold water could lead to "sudden death," daredevils like Koeberl and Hof might cause us to question how they could survive such prolonged exposures.
When core body temperature drops two-and-a-half or more degrees below normal (Jolly & Ghezi 1992), the condition is called hypothermia and it progresses through at least three stages.
The first three minutes cool the skin,
The next thirty minutes, or so, result in superficial neuromuscular cooling, and
Finally, immersion for greater than thirty minutes can pose a risk of hypothermia by inducing deep tissue cooling that drops core body temperature.
Hypothermia can be a serious condition, sometimes requiring hospitalization. In one extreme case, a 52-year-old Italian mountaineer was trapped in a crevasse for seven hours. His core temperature dropped to 79F, almost twenty degrees Fahrenheit below normal. Upon rescue, he suffered a heart attack. After six hours of continuous cardiopulmonary resuscitation and rewarming to nearly 97F, his heart began beating regularly on its own. He spent seven weeks recovering in the hospital and was discharged after a complete neurological recovery (Kuhnke et al. 2009).
Nonetheless, one of the amazing things about cold water immersion is that "cold can protect life as well as endanger it" (Harries 2003). Unlike hypothermia induced by frigid air, which can result in frostbite, liquid cold water is insufficient to freeze human cells. Thus, even victims of cold-water drowning can survive prolonged periods without breathing or a pulse, when arriving at the emergency room in a hypothermic state. Weinberg 1993 cautions, "although the clinical presentation may be such that the victim appears dead, aggressive management may allow successful resuscitation in many instances."
When I asked an emergency room physician about cold water drowning victims, she cautioned me "No cold-water case is pronounced dead until they’re warm. We always attempt rewarming and resuscitation. I've brought people back to life as much as 24hrs after they drowned in cold water."
For most people, the shiver response is a good indication that they’ve been in the ice bath for long enough to benefit. While the best way to prevent hypothermia is to ensure that the person in the ice bath can emerge of their own volition – without coercion, without incentives to stay longer, without shame, bullying, or inducements – there is a good rule of thumb on dosing cold water exposure that works well for those starting out:
Go cold enough to gasp, long enough to shiver.
Cardiac Arrest
The most complicated, and hypothetical, of all the dangers described in Tipton’s 'Kill or Cure' paper is related to cardiac arrest via autonomic conflict. Tipton hypothesizes that "Perhaps one of the most powerful and reproducible ways of inducing autonomic conflict is by rapid submersion in cold water (<15°C) with attempted breath holding. This activates two powerful autonomic responses: (i) the cold shock response (i.e., gasp reflex), and (ii) the diving response."
When our faces are submerged in water, our bodies automatically slow down our heart rate and metabolism to conserve oxygen -- a phenomenon first documented in 1875 and now called "the dive reflex" (Wolf 1965). The heart rate response to breath is now well-documented. In the extreme, reductions in heart rate of 44% have been observed in elite, breath-hold free divers (Lamaitre et al. 2005).
According to his hypothesis, autonomic conflict can lead to an irregular heartbeat or a fatal cardiac arrest that would be undetectable in an autopsy.
What's important to recognize is that the risk of autonomic conflict only exists when the subjects are attempting a breath hold. Partly for this reason, you should never attempt a breath hold while in the ice bath.
Use structured, continuous breathing while practicing whole-body cold-water immersion.
Never combine hyperventilation, breath holds, and water immersion.
Hyperventilation purges the bloodstream of carbon dioxide. Because it is accumulation of carbon dioxide in the blood that creates the urge to breathe (not a deficit of oxygen), divers who hyperventilate prior to their dive can run out of oxygen before their carbon dioxide levels are restored. Thus, they could lose consciousness before they experience the urge to breathe.
Tipton’s concerns for autonomic conflict are different from concerns about shallow water blackout from hyperventilation and breath holds in the water. Nonetheless, both concerns can be mitigated by entering the water feet first and maintaining constant, structured breathing.
Operating during rewarm
For a long time, my personal best was 14 minutes in my Forge, and the effects were considerable. When I emerged, it felt like every muscle in my body was trembling. I had lost all fine motor control, which made using my mobile phone or driving my car impossible.
It took about ten minutes to rewarm enough so that I could drive myself to hot yoga, and even then, it probably wasn't a good idea.
I got to yoga late, but the Instructor let me join the class anyway. I was still discombobulated and having trouble getting into some sort of a half-monkey-moon-twist pose that I don’t remember.
The Instructor gave me a couple of verbal instructions I didn’t understand. Maybe she was a little frustrated with me, or maybe she was being sympathetic, but in either case she walked over and put her hands on my back, gently guiding me into the right pose and the rest of the class went really well.
Afterwards, I approached her in the hallway to thank her for the correction.
She said, “No problem. That’s what we do here! But may I ask you a question?”
Sure,” I said.
“Was it cold enough for you in there?” she asked.
“Oh, I thought it was plenty hot!” I said.
“I dunno,” she answered. “When I put my hand on your back, you felt cold so I was thinking, ‘Gee, I’d better turn up the heat in here!’ “
I had to explain my experience in the ice bath right before class.
The most dangerous thing about my 14-minute ice bath was probably the 20 minute drive I made afterwards.
In my case, afterdrop was probably a more serious concern than hypothermia. During cold immersion, the human body will automatically employ vasoconstriction to limit blood flow to the extremities and conserve heat for the vital functions in the core. When emerging from the ice bath, blood returns to the cold limbs and begins rewarming the muscles. But the blood that goes through the extremities must eventually return to the heart. Afterdrop is a phenomenon in which the core body temperature continues to fall even while rewarming, because blood returning to the core is colder after having passed thru the frigid arms and legs (Romet 1988).
For example, Park (2021) studied rectal temperature response to immersion in 10C water, and discovered that temperatures can continue to drop even 30 minutes after emerging from the cold.
While it's unlikely that afterdrop poses a serious physiological risk, Seo et al. (2013) have investigated the psychological effects of afterdrop and suggested that subjects experience cognitive and attentive impairment as their core temperatures return to normal.
That's why it was a bad idea for me to drive so soon after an extended ice bath.
Always allow time for rewarming before operating tools, machinery, or weapons.
Shallow water blackout
There is particular caution that comes with immersing the face in the water – you can’t breathe when your nostrils are underwater. When our bodies enter cold water, we experience an involuntary urge to suck in our breath called the "gasp reflex" (Mekjavic et al. 1987).
When unable to gain control of our breath, we run the risk of hyperventilating and (ultimately) losing consciousness. As you can imagine, passing out in the ice bath is very dangerous, because of the risk of inhaling water and drowning. For this reason, never combine hyperventilation with cold water immersion, and to ensure that your nostrils are clear for breathing when you experience the gasp reflex, always enter the ice bath feet first.
Investigative journalist Scott Carney has documented more than a dozen deaths by shallow water blackout that can be attributed to loss of consciousness during breath holds while swimming (Carney 2023).
it is true that diving without the use of an underwater breathing apparatus (called free diving) is extremely dangerous. Even highly experienced free divers sometimes experience blackouts in the water that result in drowning – albeit probably for different reasons than autonomic conflict.
Because the Method involves hyperventilation prior to cold water immersion, practitioners who attempt breath holds under water may lose what is called the "urge to breathe" and deplete their oxygen stores.
This tragic phenomenon is all too common among free divers (diving without the use of underwater breathing apparatus).
Inexperienced or untrained divers frequently hyperventilate before diving to increase their blood oxygen levels. This method is dangerous as hyperventilation causes them to expel large volumes of carbon dioxide, lowering their pre-dive carbon dioxide levels. They, therefore, experience the "urge to breathe" much later in the dive, which may lead to an underwater blackout. This mostly happens because the diver has depleted their oxygen stores before reaching the blood pH threshold to trigger the "urge to breathe", which would have alerted them to return to the surface. - Allen & Allen (2022)
To mitigate the danger of shallow water blackout, never, ever combine hyperventilation with underwater breath holds. To obtain the benefits of the ice bath, and minimize the risks, it is essential to breathe during the experience.
Ice bath safety
There are four important safety precautions that mitigate the risks of whole-body cold-water immersion:
· Always Forge sober, and supervise children.
· Always enter the Forge feet first, keeping your head above the level of the water.
· Allow yourself time to rewarm before driving or doing anything that requires your cognitive attention.
· Breathe.
Ice bath overdose?
Remember my friend Micah Lowe, who measured his heart rate during his ice bath? Micah is an advanced biohacker. He's in great shape, he keeps up with the science of holistic health, and he has an extraordinary curiosity that motivates him to experiment with his limits.
This is what he said:
Thomas, I think I finally overdid it.
Winter is almost here. It's about 34F outside now. I did six minutes in my ice bath, then I did my recovery workout outdoors in the cold while I was still wet.
That was a lot of cold, and I felt some brain fog after. I rewarmed with my Sauna Space lamps, went down for about an hour nap, and then I felt great.
But maybe I did too much?
His experience raises some questions about what can happen when we overdose on deliberate cold exposure.
Non-shivering cold thermogenesis
The risk of cold overdose depends on the temperature and duration of your exposure and your level of prior cold acclimation. The more brown fat you've recruited from your past cold practice, the more comfortable you will feel in the ice bath without shivering.
Most cells in the human body have hundreds of mitochondria to perform energy conversion, but brown fat cells are packed with thousands, because the most important function of brown fat is to fuel non-shivering cold thermogenesis. When exposed to cold, the mitochondria in brown fat oxidize glucose and fat (e.g., triglycerides) to defend core body temperature by producing heat. The more prior cold exposure you’ve had, the more your body will adapt by increasing brown fat depots and 'beiging' white fat by adding more mitochondria. More mitochondria means more non-shivering cold thermogenesis, thus more heat production, and greater comfort at lower temperatures.
A study of Danish winter swimmers discovered that an average of 11 minutes a week of cold water swimming was sufficient to maintain brown fat for cold thermogenesis (Søberg et al. 2021). The study didn't explore the minimum effective dose for activation, retention, or recruitment of brown fat, so it's possible that fewer than 11 min/week at water temperatures less than 40F could be sufficient. But the study did conclude that it didn't matter whether you did all 11 min at once, or spread it out over several days. That is, frequent, short exposures seemed to be as effective as less frequent, longer plunges.
Perhaps the most spectacular case of cold-water tolerance comes from the story of an Icelandic fisherman who was capsized in the North Atlantic Ocean. He swam 6 hours to shore in 5-6oC (about 40oF) water, then walked another 5 km over land in air about minus 2oC. At about 6’4”, 275 lb, the fisherman had the advantage of thick layers of subcutaneous fat that helped protect his core temperature. Nevertheless, when researchers attempted to recreate the conditions of his swim by studying his vital signs during a 42oF plunge in the laboratory, the fisherman’s core temperature dropped almost 2oF in 83 minutes without ill effects characteristic of hypothermia (Keatinge et al. 1986).
His experience shows that ice bath temperature and duration is insufficient to describe how much cold dose is too much – individual physiological characteristics likely make a big difference, too. In the chapter on ‘Practices and Protocols’ I’ll describe a method for measuring cold dose in a way that’s specific to your own body, so you can track how much cold dose you’re getting. But for now, I’ll focus this section on what can happen when you get too much.
Brain Fog
The brain is the most demanding single metabolic organ in the body, using as much as 30% of your total metabolic energy. However, during extreme cold exposure, so much energy is going into cold thermogenesis that the energy available for cognitive functions in your brain may be diminished. The drain might explain why people suffer deficits in working memory and mathematical reasoning during cold exposure.
For example, animal studies have revealed physiological changes in the brain during acute cold exposure that may explain the brain fog Micah experienced. Even small reductions in body temperature (mild hypothermia) have been shown to promote the phosphorylation of tau proteins in the brain, and tau phosphorylation is another of the signature physiological markers of Alzheimer's. In laboratory studies, chronic cold exposure induces tau phosphorylation and impairs memory and learning in rats (Ahmadian-Attar et al. 2014). While the cold-induced tau phosphorylation reverses upon rewarming in healthy subjects, when rewarming capacity is compromised, the resulting tangle formations can become permanent.
That doesn't mean the ice bath is making Micah stupid. In fact, the opposite is true because Micah is stimulating his thermoregulatory systems with his practice of short-term deliberate cold exposure.
Keeping brown fat active with a regular practice of cold and recovery contributes to the long-term health of the brain. For example, the increases in insulin sensitivity associated with active brown fat likely improve metabolic function throughout the body, including the brain. But brown fat does more than cold thermogenesis. It is also a secretory organ, which means that it produces hormones and other signaling agents that communicate to other areas of the body.
For example, brown fat produces a neuroprotective hormone called FGF21 that may contribute to long-term brain health (Tournissac et al. 2019). FGF21 has been shown to reverse cognitive deficits in rats, correct blood-brain barrier disruptions, protect against neurotoxicity, curb alcohol consumption in monkeys, and extend life in mice. Additionally, cold exposure is associated with increased levels of brain-derived neurotrophic factor (BDNF), which promotes memory functions and formation of new neural structures (An et al. 2015). Data from rats suggests that cold water exposure promotes proliferation of endothelial progenitor cells that improve blood circulation in the brain and promote healing from traumatic brain injury (Zhou et al (2017).
Frostnip and frostbite
Frostbite, and it’s more mild form called frostnip, is distinct from non-frostbite cold injury (NFCI). Frostbite occurs when the water inside skin cells freezes into ice. It is a very painful condition that can result in permanent damage -- especially to fingertips and toes. Although there is a remarkable species of tree frog that can be frozen solid and will spring back to life upon thawing (Moalem 2007), you probably know that human flesh is not amenable to such treatment. In extreme cases, frostbite can necessitate amputation of extremities.
One of the inherent advantages of the ice bath, compared to frigid air cryotherapy, is that the temperature of the water in the ice bath can never be cold enough to freeze the water inside skin cells, because the freezing point of water in the skin is lower than that of the water in the ice bath -- with one notable exception. It is possible to lower the freezing point water in the ice bath by adding salt.
For example, adding Epsom salt to the ice bath will soften the ice and lower the freezing point of water. Thus, it probably made sense to two of my engineering graduates to dump an entire 18lb bag into the ice bath at the Morozko Forge studio in Phoenix AZ. What did not make sense was turning the temperature controller down to 30F.
The freezing point of human blood was established back in 1930 as 31oF (-0.55oC). Thirty years later, two courageous British scientists sought to measure the freezing point of their own pinky fingers by applying a tourniquet to cut off blood flow while holding them in cold brine (28.6F, or -1.9C) for 7 straight minutes (Keatinge & Cannon 1960). They reported that each finger, when removed, "felt and sounded hard when tapped with a piece of wood."
Had my engineering grads been aware of these intrepid British adventurers, they might have rethought their own self-experimentation. However, a few hours after dropping the temperature controller, they plunged their whole bodies into an ice bath filled entirely with 20" of slush.
They did seven minutes each.
Two days later I got a call from one of them, asking me about painful skin all over his body. He said it felt like a sunburn, but he felt it almost everywhere, and he hadn't been out in the sun.
I was flummoxed.
So I asked him, "What about your plunge buddy? Does he feel the same?"
He did.
It turns out that they were both experiencing frostnip, which is a mild and reversible case of mild frostbite. When our engineers dropped the temperature of their ice bath below freezing, they introduced the risk of freezing their own skin.
Nonetheless, they experienced nothing worse than a couple of days of discomfort and they both recovered completely.
Water borne infection
There are two advantages to cryotherapy in frigid air, compared to cold water:
Some people don’t like to get wet, and
Air cryotherapy relieves concerns about water quality.
These reasons can go together. That is, at spas, gyms, or clinics that serve lots of customers, there is always a concern about the water quality in shared pools and hot tubs. For this reason, the water in these shared spaces is always heavily chlorinated to prevent the spread of infectious diseases.
Chlorine disinfection is the same technology that is used in municipal water treatment systems to eliminate waterborne bacteria and viruses. It seems that every year brings news of some municipal water treatment system that has failed to complete disinfection of their water supply. That’s typically when customers are instructed to boil their water before drinking, to prevent ingestion of some pathogenic organism like e. coli. Gastrointestinal discomfort is most common, but in vulnerable subpopulations (babies, elderly) a water borne disease can be deadly.
Water quality can be a legitimate health concern related to hot tubes, ice baths, swimming pools, and drinking water supplies. To protect against contamination by bacteria and viruses, water treatment plants typically dose chlorine in concentrations high enough to ensure that it travels through the entire network of water distribution pipes. The chlorine that reaches your faucet is called a residual concentration and it’s there to ensure that it maintains some protection against reintroduction of infectious pathogens in the city water pipes.
Chlorine is not healthy
There is no naturally occurring form of chlorine that disinfects water via oxidation. Although chloride is ubiquitous is sea water and table salt, the forms of chlorine used for disinfection are highly reactive and unhealthy. Chlorine isn’t healthy to breathe, nor to drink. What’s worse, the form of highly reactive chlorine used in pools, hot tubs, and water treatment plants can create carcinogenic by-products called trihalomethanes – a single carbon atom with one hydrogen and three chlorines (or bromines) attached. Thus, bathing in chlorinated water of any kind can create health risks.
The best way to avoid production of trihalomethanes is to avoid the use of chlorine altogether. For example, many water treatment plants in Europe will use ozone for disinfection instead of chlorine or bromine. The degradation products of ozone disinfection are just oxygen, carbon dioxide, and water. That’s because ozone is a highly reactive form of oxygen made up of three oxygen molecules (instead of just two).
Ozone is a more powerful, safer disinfectant than chlorine – but there is a tradeoff. The lifetime of ozone in water is very short. That is, it’s good as a shock disinfectant, but it will never provide enough residual concentration to protect the water in the distribution pipes after it leaves the treatment plant. For that reason, even the European cities that use ozone will still add some chlorine to the water before it leaves the plant.
However, for ice baths, ozone disinfection without residual chlorine is ideal.
Ozone disinfection protects your ice bath
The most powerful and safe disinfecting agent available for water treatment systems is ozone -- more powerful than chlorine and bromine, and safer because it consists only of pure oxygen. The usual form of oxygen in the atmosphere consists of two oxygen atoms joined together in a single molecule with the chemical formula O2. However, when O2 is exposed to high energy field – such as an electric arc or ultraviolet light– it recombines into a more reactive combination of three oxygen atoms called ozone, or O3.
The third oxygen atom is what makes ozone such a strong oxidizing agent. Ozone will destroy pathogenic bacteria and viruses by scavenging electrons from the carbon atoms in their chemical structure -- eventually turning microbes into carbon dioxide. For example, ozone can deactivate the deadly ebola virus (Davies 2015). Ozone will also oxidize other contaminants like algae and dead skin cells. It even destroys organic pollutants like benzene, toluene, xylenes (BTX), methyltertbutylether (MTBE), and volatile organochlorinated compounds.
Ozone is terrific for cleaning water, but is rarely used in swimming pools and municipal drinking water distribution systems in the United States because it has such a short lifetime. The problem with ozone is instability. Even without something to react with, ozone as O3 will devolve back to plain O2 oxygen -- sometimes in seconds.
To ensure continuous disinfection in a pool, an ozone system would have to be running all the time. Chlorine is more stable than ozone, and it maintains high concentrations in water for longer. That's also why ozone isn't used in swimming pools, because unless you produce ozone 24 hours a day, 7 days a week, most pools would lose all their ozone to natural degradation less than an hour after the pool pump turns off. By contrast, the longer chlorine lifetime means that the pool pump only needs to run for several hours a day.
Even with constant production, maintaining ozone levels throughout an entire pool would be difficult during the warm summer months, because warm water destroys ozone. For example, in hot tubs, ozone alone is insufficient for disinfection. That’s why hot tubs that use ozone still require chlorination or bromination.
In hot water, ozone has two disadvantages:
The saturation concentrations of ozone in hot water are much lower, because the hot water temperatures boil the ozone out of solution and into the air.
Heat speeds up the ozone degradation.
However, in cold water ozone is ideal.
Ozone therapy
Ozone levels in the water are measured indirectly, using an oxidation-reduction potential (ORP) meter that measures the activity of electrons in the water. An ORP meter is a specialized piece of laboratory equipment that is easy to learn, but difficult to interpret. I learned how to use one when I was a graduate student in environmental engineering, studying water chemistry. ORP readings can be translated into concentrations. The higher the ORP, the more ozone is present in the water and the faster disinfection happens.
High concentrations of ozone are sometimes used medicinally. For example, ozone therapy is used to heal skin (Liu et al. 2022), in dentistry (Suh et al. 2019), and to treat fibromyalgia (Tirelli et al. 2019). Recently, high doses of ozone have been used as an anti-ageing therapy (Scassellati et al. 2020) -- but not by bathing in it, or by breathing it. When administered by a qualified medical professional, ozone can be added directly to blood that has been removed via phlebotomy, treated, and then returned to the bloodstream. Ozone can also be administered via insufflation – i.e., into body cavities that are not directly connected to the lungs, such as the ears, vagina, or anus.[1]
Ozone in the water can be healthy, but ozone in the air can be problematic. The United States Environmental Protection Agency (USEPA) recognizes airborne ozone as a toxic pollutant, because it is such a strong oxidant that in high enough concentrations it attacks the cilia in the throat and membranes in the lungs.
In the upper reaches of the atmosphere, ozone is formed by high-energy wavelengths of light from the sun. There, it shields the lower atmosphere from harmful, short wavelength portions of the ultraviolet spectrum. That’s why the ozone hole that was discovered in the 1980’s created such environmental concern.
The ozone hole was an area in the stratosphere that was depleted of ozone, thereby allowing the shortest wavelengths of ultraviolet light known as UVC and UVB to penetrate the atmosphere and reach the ground. UVC is particularly dangerous, and normally blocked completely by the ozone layer. On the other hand, some UVB exposure is necessary for humans to synthesize Vitamin D in their skin. The concern regarding an ozone hole is that too much UVB causes skin cancers and eye damage.
Ironically, the ozone hole was created by the release to the atmosphere of halogenated hydrocarbons, of which trihalomethanes are one of many. Until they were phased out in the late 1980’s, these molecules containing carbon, hydrogen, fluorine, bromine, and chlorine were commonly used as refrigerants, blowing agents, and in aerosol cans. Once the halogenated hydrocarbons diffused up into the stratosphere, the sunlight there would ionize them into highly reactive radicals that catalyzed destruction of ozone – thus creating the hole.
In contrast with the stratosphere, where ozone is beneficial, at the surface of the earth ozone is a pollutant that contributes to smog. One of the big differences is that the upper atmosphere ozone occurs naturally and is essential, whereas ozone in city smog is artificial.
You might smell natural ozone in the air after a lightning strike, but most people are more familiar with the smell of ozone created by the spark of an electric train or some other electric sparking toy. For most people, their nose is a very sensitive environmental monitoring instrument. Humans have evolved to detect odors that are both harmful and helpful to our survival, and most noses have low detection limits for certain harmful pollutants including ozone and hydrogen sulfide (rotten eggs).
Measuring ozone in the air requires a different type of sensor than the ORP meter used to measure it in the water. I’ve monitored the concentrations of ozone in my Morozko ice bath, to see how much ozone escapes the water and resides in the air above the water. I’ve never detected concentrations that exceed EPA ambient air standards – even with the lid on. That suggests to me that breathing ozone is not one of the risks of practicing ice baths in a Morozko, because the short lifetime of ozone ensures that it degrades rapidly in the air above the surface of the water.
[1] You'll never hear a story about how someone has improved their health or cured their sickness by treating themselves with chlorine.
yo know im not a big fan of forusm, blog or other things BUT i decided to try cold therapy been second month onit and now reading literature and thing like this. I trying everything i also combined therapy with supllements, and vitamins, got this https://www.semenex.net/ supplement in combination with other vitamins + cold theray (im not a boy anymore but an old gronw man haha this is not for youngster! So Doc, thanks a lot for article i will definitely buy your book later just to support you!!
Thank you 🙏