The red eyes, itchy skin, and sharp pool smell that many swimmers experience are commonly blamed on chlorine. But chlorine itself is not usually the irritant. The real culprits are a family of compounds called chloramines — and understanding them explains a great deal about why conventional pools can be so uncomfortable, and why changing the disinfectant chemistry changes so much.
What chloramines are
Chloramines are compounds of chlorine and nitrogen. They form when chlorine reacts with nitrogen-containing organic material dissolved in pool water — primarily urea from urine and sweat, and amino acids from skin proteins. In any pool where people swim, these nitrogen compounds are constantly present. The reaction is rapid and chemically unavoidable: no amount of balancing, shocking, or maintenance can prevent chloramines from forming in a chlorine pool. They can only be managed after the fact.
Three chloramine compounds form in sequence, each more irritating than the last: monochloramine, dichloramine, and trichloramine (also called nitrogen trichloride). Trichloramine is the most concerning. It is highly volatile, concentrating in the air layer just above the water surface. It is responsible for the characteristic sharp odour that most people associate with swimming pools — what is commonly called "the smell of chlorine" is almost always trichloramine.
What chloramines do
Exposure to chloramines in pool water causes stinging and reddening of the eyes, skin irritation, and dryness after swimming. Trichloramine vapour in the air above the water surface is a respiratory irritant. Children and anyone who spends extended time in the water — at the surface where trichloramine concentrates — are most directly exposed.
People who train regularly in indoor pools often develop respiratory sensitivity over time, and there is a well-documented association between trichloramine exposure and breathing difficulties in competitive swimmers. This is not an allergy to chlorine — it is a response to chloramines, which are chemically distinct from chlorine itself.
How bromine changes the picture
Bromine disinfects pool water just as effectively as chlorine, but it does not form chloramines. When bromine reacts with nitrogen compounds in the water, the reaction products are different and substantially less irritating. A pool running on bromine chemistry eliminates chloramine formation entirely — not by managing chloramines after they form, but by removing the chemical precondition that creates them.
The result is water that is gentler on eyes and skin, free of the sharp pool odour, and more comfortable for extended swimming — especially for children and anyone with sensitivities.