The burning and redness experienced after swimming is often blamed on chlorine, but this is a misconception. While chlorine is a necessary disinfectant, it is not the primary cause of eye irritation. The true source of discomfort is a chemical byproduct that forms when chlorine reacts with organic matter introduced by swimmers. The familiar “chlorine smell” of a pool is actually the odor of these irritating chemicals, which signals a breakdown in water quality.
The True Culprit Behind Red Eyes
The actual irritants are compounds known as chloramines, which form when free chlorine combines with nitrogen-containing substances from the human body. These nitrogenous compounds are introduced into the water through sweat, urine, body oils, and cosmetics. The reaction creates monochloramine, dichloramine, and trichloramine, all of which are chemical irritants.
The presence of chloramines indicates that chlorine is being consumed by reacting with contaminants rather than actively killing germs, reducing the pool’s effectiveness as a sanitizer. The burning sensation, eye redness, and strong chemical odor are direct indicators of high chloramine levels. A pool with a noticeable “chlorine smell” has poor water quality due to a high concentration of swimmer waste, not necessarily over-chlorination.
Chloramines can also turn into gas, which is more common in indoor pools with limited ventilation. This gas leads to respiratory irritation for everyone in the area. Dichloramine and trichloramine byproducts are specifically responsible for the eye and respiratory irritation experienced by swimmers.
Understanding the Biological Reaction
The irritation from chloramines results from a mild chemical reaction on the eye’s delicate surface, sometimes called “swimmer’s eye.” The primary issue is the disruption of the tear film, a thin, protective layer of moisture covering the eye. This tear film is designed to keep the eyes smooth, lubricated, and protected from irritants.
Chloramines and the pool water wash away or break down this tear film, leaving the underlying tissue exposed. This disruption causes the eyes to feel dry, gritty, or itchy, making them more susceptible to irritation. The chemical irritants then directly affect the conjunctiva, the clear membrane covering the white part of the eye and the inside of the eyelids.
The body’s response to this chemical irritation is to trigger vasodilation, the widening of the small blood vessels in the conjunctiva. This increased blood flow causes the visible redness and stinging sensation after swimming. This reaction is a form of mild chemical conjunctivitis, a non-contagious inflammation of the eye’s surface.
Practical Steps for Eye Protection
Swimmers can take several actions to protect their eyes and minimize exposure to chloramines. Showering thoroughly before entering the pool helps rinse off sweat, oils, and personal care products that contribute to chloramine formation. This simple step reduces the amount of organic matter entering the water, allowing the chlorine to focus on sanitation.
Wearing properly fitted, watertight swim goggles is the most effective physical barrier against irritants. Goggles prevent direct contact between the pool water and the eyes, protecting the natural tear film from being washed away. Ensuring the goggles fit snugly around the eye socket is important for creating a reliable seal.
After swimming, rinse the eyes with fresh, clean water or a sterile saline solution to flush away any residual chemicals. Lubricating eye drops, often called artificial tears, can be used to re-establish the balance of the tear film and soothe dryness.
If redness or irritation persists for more than a few hours, or if there is pain or discharge, seeking professional medical advice is recommended.