The smell of chlorine

Long before the pool itself comes into view, the smell announces it: down a hallway, past the front desk, through a set of double doors still swinging from the last person who walked through them, the smell reaches the nose ten or fifteen feet ahead of the water. It concentrates indoors far more than outdoors, trapped by low ceilings and mechanical ventilation systems sized for a different, quieter era of the building, which is why an indoor natatorium smells stronger at six in the evening during adult lap swim than an outdoor pool ever does at noon. The compound responsible, chloramine, is not free chlorine at all but the byproduct of chlorine reacting with sweat, sunscreen, and urine already present in the water, so the sharper the smell, the more organic material the pool has processed rather than the more sanitizer it contains. A well-maintained pool, counterintuitively, often smells fainter than a poorly maintained one, which confuses first-time visitors who associate a strong smell with cleanliness, and lifeguards who have mostly given up correcting them. The scent clings to swim bags for days afterward, to goggle straps permanently, to the pages of a paperback left too close to the deck for one afternoon. Competitive swimmers often stop noticing it consciously after a few seasons, and register it again only on the rare day the filtration system goes down and the water, oddly, smells like almost nothing at all.

H. G. Plimsoll