Humans breathe nitrogen, but the body does not actively use it. Understanding air composition and how our respiratory system interacts with it provides a clearer picture. While oxygen is the gas our bodies use for survival, nitrogen is also present in the air we inhale and exhale. This article explores nitrogen’s involvement in breathing.
The Air We Breathe
Earth’s atmosphere is a mixture of gases, with nitrogen being the most abundant component. Dry air consists of approximately 78.08% nitrogen by volume. Oxygen, essential for human life, makes up about 20.95% of the air. Other gases, such as argon (around 0.93%) and carbon dioxide (about 0.04%), are present in smaller quantities. Every breath taken inevitably includes a substantial amount of nitrogen.
Nitrogen’s Journey in Our Lungs
Once inhaled, nitrogen travels through the respiratory system and reaches the lungs’ alveoli. Unlike oxygen, which readily diffuses across alveolar membranes into the bloodstream, nitrogen is largely inert and does not participate in chemical reactions within the body under normal atmospheric pressures. Most inhaled nitrogen is then exhaled unchanged, as the body does not metabolically utilize it. A small amount can dissolve into the blood and tissues, but it remains unreactive and is eventually expelled. Nitrogen also plays a mechanical role within the lungs by helping to keep the alveoli inflated, which maintains the surface area for efficient gas exchange.
Is Nitrogen Harmful to Breathe?
Under normal atmospheric conditions, nitrogen gas is not harmful; in fact, it serves a beneficial purpose. It acts as a diluent, reducing the concentration of oxygen in the air. This dilution is important because breathing pure oxygen can be toxic to the body over time, potentially damaging lung tissues. Nitrogen helps maintain a balanced oxygen level that is safe for sustained respiration.
There are, however, specific circumstances where nitrogen can pose problems. In environments with very high pressure, such as during deep-sea diving, increased pressure causes more nitrogen to dissolve into the body’s tissues and bloodstream. This can lead to nitrogen narcosis, sometimes called “rapture of the deep,” which impairs judgment and motor skills, similar to alcohol intoxication.
Additionally, if a diver ascends too quickly, the dissolved nitrogen can form bubbles in the blood and tissues, resulting in decompression sickness, commonly known as “the bends.” This condition can cause significant pain and neurological symptoms. While nitrogen itself is not toxic, a high concentration of nitrogen in an enclosed space can displace oxygen, leading to oxygen deprivation and asphyxiation, which can be fatal.