Scuba divers breathe using equipment that decompresses the breathing gas they carry. This includes their scuba tank, the breathing gas it is filled with, and a two stage regulator that allows you to inhale and exhale underwater.
Breathing while scuba diving is a completely new process, but all the equipment involved keeps it safe and responsible. Keep reading to learn how you breathe while scuba diving, what you use to breathe, and find answers to a few related questions.
How Do You Breathe While Scuba Diving?
To breathe while scuba diving, you must have your mask in place over your eyes and nose and your regulator in your mouth. You breathe smooth and relaxed through the regulator, never holding your breath and making sure you empty your lungs with each exhale.
Breathing while scuba diving doesn’t feel natural at first, so you need to take the time to practice it before you get in the water. Once you learn to control your breathing you limit your chance of injury and steady your air consumption to stay under the water longer.
What Is in a Scuba Oxygen Tank?
Most scuba tanks use purified compressed air, but there are specialized breathing gas blends that affect the conditions in which you can dive. Your diving gas options include:
- Compressed air
- Nitrox
- Trimix
- Heliox
- Hydrox
No scuba tank for diving purposes contains pure oxygen. Any tank with 100 percent oxygen on board is for medical emergencies, such as DCS, and is not suitable for breathing. The air that you breathe is actually mostly nitrogen, and anything greater than the percentage of oxygen in atmospheric air poses a toxicity risk.
Compressed Air
Compressed air is just atmospheric air compressed for your scuba tank. It includes many elements, including about 79 percent nitrogen and 21 percent oxygen.
Air also includes minute amounts of other elements, including:
- Argon
- Carbon Dioxide
- Neon
- Helium
- Hydrogen
This isn’t a complete list. You’ll see some of the elements in other breathing gas mixes, but some higher up on the list are too finicky or rarely occurring to use for your scuba tank.
Nitrox
Nitrox tanks use higher levels of oxygen than regular air, anywhere from 20 to 40 percent. This breathing gas mix lets you absorb more oxygen than nitrogen, decreasing the chances of nitrogen narcosis or decompression sickness.
Nitrox lets you stay at your depth for a longer period, but you won’t be able to descend as far.
Trimix
Trimix tanks replace some of your nitrogen and oxygen content with helium, and they come in three varieties:
- Normoxic (same oxygen as air)
- Hyperoxic (more oxygen than air)
- Hypoxic (less oxygen than air)
The specific blend you use depends on what you need from the mix. Hypoxic breathing gasses cannot be used at the surface.
Heliox
Heliox uses either as much oxygen or less than regular air, and it replaces nitrogen with helium completely. This lets you extend both your depth and your bottom time, but you still cannot use it at the surface.
Heliox is much more expensive than other mixes.
Hydrox
Hydrox is relatively new. It has an extremely low oxygen percentage and uses mostly hydrogen. This makes it more cost effective, but it’s also incredibly flammable.
Because hydrox lets you travel much deeper, it’s mostly used by commercial divers.
What Do Divers Wear to Breathe?
Divers have three pieces of gear that they often wear (apart from their scuba tank) to facilitate breathing underwater and keep their airways clear.
This includes a:
- Snorkel
- Mask
- 2-stage regulator
Each item has its uses, but you need all three for safe diving.
Snorkel
Divers wear a snorkel close to the surface to allow them to breathe without using the precious air in their scuba tanks. They can take air more easily before starting their descent.
The snorkel also helps them conserve energy and avoid taking in water after their dive. While they’re at the surface waiting to be picked up, an exhausted diver can use their snorkel to breathe air at the surface without spending as much energy staying up out of the water.
Mask
While your mask doesn’t provide you with breathable air, it helps you keep your airways open.
Scuba diving masks cover the nose, which you do not use for breathing underwater. This lets you focus on breathing through your mouth, and you don’t need to worry about taking in water through your nose.
Your mask offers other benefits that aren’t tied to breathing underwater.
Regulator
Your regulator is the powerhouse of breathing underwater. You keep it in your mouth at all times while diving by gently biting the mouthpiece and making a seal with your lips.
A regulator’s first stage attaches directly to the tank’s outlet valve. The first stage reduces the pressure in the tank to an intermediate level, and it has several hoses that can then distribute the air to your second stage and BCD.
The second stage lowers the pressure again to something suitable for breathing. It feeds you air through a demand valve that opens when you breathe in. When you exhale, that valve closes and another opens to let the air out into the water.
A regulator’s two-stage design prevents water from flooding into your mouth when you exhale or air from leaking when it’s not in use.
Do You Breathe Through Your Mouth or Nose When Scuba Diving?
You breathe through your mouth while scuba diving. Your nose is sealed in your mask along with your eyes, so it doesn’t have much breathable air to work with.
Breathing through your nose also runs the risk of breaking the seal of your mask, and you should reserve breathing through your nose for other needs.
What Happens If You Breathe Through Your Nose While Diving?
A few things can happen if you breathe through your nose while diving.
If you inhale, you reduce the amount of air in your mask. This will pull the mask tighter to your face, and it can lead to a mask squeeze if you don’t deal with it promptly.
Exhaling while diving adds to the volume of air in the mask. If the volume of air gets too high, you’ll break the seal of your mask, allowing water to flood into the mask, and then you’ll need to clear it.
When to Breathe Through Your Nose While Diving
There are a few moments when you will want to breathe through your nose while diving.
One of the first things you learn in your scuba diving course is mask clearance. With your nose inside the mask, you can breathe out through it to push water through it and clear your mask.
The other time you want to exhale through your nose is to prevent mask squeeze while descending. This happens as air is compressed by the increasing water pressure, causing your sealed mask to push onto your face.
By exhaling through your nose, you add more air to the air space and prevent pain and damage to your eyes.
Can Your Lungs Explode Scuba Diving?
Your lungs can collapse while scuba diving. It may sound like the opposite of your lungs exploding, but it starts when you build up too much pressure in your lung and tear the lung tissue.
This happens usually when a diver holds their breath while ascending, and the volume of the air in their lungs increases. When the tear occurs, it allows air to leak into the intrapleural space of your lungs. The air then pushes inward on the lung, furthering the evacuation of air and causing the lung to collapse.
References
https://www.kooxdiving.com/en/how-to-breathe-underwater-while-scuba-diving/
https://www.watersportgeek.com/scuba-diving-breathe-nose/
https://theknowledgeburrow.com/why-don-t-divers-lungs-collapse-when-they-descend/