As land mammals, we must short-circuit physiology when we scuba dive. Equalizing as we descend helps adapt our bodies to our temporary environment. Here’s why and how.
As a plane begins its descent for landing, you’ll often see parents force-feeding hard candy to their children. Believe it or not, those parents are unwittingly employing the same techniques to help kids cope with the changes in ambient pressure as scuba divers do to cope with pressure changes when we dive. In just the same way, equalizing our ears as we descend adapts our bodies to our temporary environment. Here’s why and how equalizing when diving is so important.
Pressure changes: Boyle’s Law
Water is denser than air. Consequently, when moving up and down through a column of water, there is a greater proportionate pressure change than in air. For example, when walking downstairs to the kitchen in the morning to make coffee, you’re highly unlikely to notice a change in ambient pressure. However, that same change of 10 to 12 feet (3 to 4 m) can be significant when moving through the water column. The building ambient pressure outside of your body’s air-spaces — lungs, ears and sinuses, as well as artificial air spaces such as your mask and drysuit — can be significant. You must address the pressure to avoid discomfort and, in extreme cases, injury.
Equalizing when diving: when, why and how
Cast your mind back to your high school science classes or your Open Water diving class. You may recall Boyle’s Law. It states that the pressure of a given mass of an ideal gas is inversely proportional to its volume at a constant temperature. Because of this, the water’s building pressure while diving causes the gas volume in your body’s air spaces to decrease. Failing to equalize these air spaces as you descend during a dive can, therefore, cause pain and discomfort when those areas are “squeezed.”
Equalizing when diving — “adding” air volume to those air spaces so that that they approximate the ambient pressure outside of your body — is simple. There are four key areas when it comes to equalizing when diving.
The lungs are the most important area to equalize as you’re changing depth during your dive. Luckily, it’s easiest and most instinctive to do so. You only need to do one thing in order to equalize the lungs: continue breathing slowly, calmly and deeply throughout the dive.
If diving in a drysuit, you’ll need to add bursts of air to the suit via a low-pressure inflator button on the front of the suit as you descend. Doing so helps you avoid suit squeeze, and means you’ll have a much warmer and comfortable dive.
The mask creates an artificial air space that is subject to pressure change, just like any other natural air space in diving. If you don’t equalize your mask, it may lead to a red “ring of confidence” around the eyes in mild cases, causing no more than embarrassment later that day as the ring lingers. In more serious cases, not equalizing this space can lead to bruising and bloodshot eyes. It’s easy to avoid these potential issues and equalize your mask.
Although you continuously breathe in and out of your mouth while diving, to equalize the mask, you’ll simply breathe out through your nose from time to time during descent. This adds air to the mask air space. Many divers accomplish this as a happy side-effect of clearing small amounts of water that may have dribbled into the bottom of the mask.
Ears and Sinuses
The most obvious areas requiring equalization are the ears and sinus cavities. You may have even felt a mild squeezing sensation when duck-diving in a swimming pool before you became a diver. A diver needs to equalize approximately every two to three feet (1 m). Doing so is particularly important in the first 15 to 30 feet (5 to 10 m) of the dive. This is when the largest proportional pressure change takes place.
The art of equalizing ear and sinus cavities is to do it early and often. Equalizing your body air spaces will, as you gain experience, become instinctive. There are three main techniques for equalizing these areas.
Blow gently against pinched nostrils. This is known as the Valsalva technique, which is the first taught and often most effective way to equalize. With your fingertips pinching your nostrils and your mouth closed, blow gently, just as you would when you’re blowing your nose into a tissue. The process adds air to your middle ear and assists in equalizing. Miming this process also works as a useful reminder to your buddy to do likewise if they appear to be struggling.
Rotate the jaw and move your head from side to side. Wiggling your jaw in a circular or side-to-side motion can also help in equalizing as you descend.
The simple act of swallowing helps to redistribute air and helps to equalize air spaces.
Depending on your own physical traits, any one of the above — or a combination of all three — may work effectively for you.
Many divers, particularly those new to the sport, struggle with equalization on the first few dives of a trip. Some of that is psychosomatic — the anxiety of those first dives manifesting as ear problems. Some is poor technique. Try the following to assist with effective equalization and avoid ear and sinus problems.
Relax before the dive. Address any concerns you may have with your buddy, dive leader, divemaster or instructor. Don’t let anxiety overwhelm you.
Don’t dive with a cold or congestion that will adversely affect the migration of air in your body’s air spaces.
Descend in a slow and controlled manner. Give your body time to equalize as necessary.
Equalize early and often — before any issues occur. Don’t wait until you actively feel an increase in pressure or a squeeze. Equalize regularly throughout your descent regardless of whether or not you feel like you need to.
If it’s available, use a line to control your descent. You can grasp the line — with your right hand so you can adjust buoyancy with your left arm — pause, signal your buddy and control your descent if required. This process allows you ample time to equalize.
If you’re making a free descent in open water, position yourself for effective equalization. Hold your jacket’s low-pressure inflator in your left hand while you leave the surface and make your initial descent. Leave your right hand free for pinching your nose to equalize, adjusting your drysuit (when worn) and signaling to your buddy.
If your techniques aren’t working, swim very slightly shallower, around three feet (1 m), and try again. Going violently up and down several feet or meters will only exacerbate the issue. Small buoyancy adjustments and continual equalization are far more effective.
Sometimes it’s just not your day. If you can’t equalize for whatever reason, abort the dive. Don’t force the issue and potentially hurt yourself or compromise everybody’s dive. There’s no shame in sitting one out.
Although you’ll learn how to take care of your air spaces and equalize during your first lesson and first dive, it’s information that’s sometimes forgotten. Using these simple techniques and tips will help you to have a more comfortable and successful dive every time.