French health authorities repeat it every summer: a young child can drown in under three minutes in about 20 centimetres (8 inches) of water, without calling for help. Unlike in films, a drowning person doesn't scream or wave their arms: they struggle silently to breathe. Bathtub, paddling pool or poolside, the only real protection is an adult who never takes their eyes off the child.
Chlorine on its own is fairly gentle. But when it combines with urine, sweat and other grime from swimmers, it forms chloramines, which cause stinging eyes and that classic 'chlorine smell'. A well-kept pool barely smells at all. Shower before you swim and never pee in the water.
Muscle mass slowly shrinks with age, putting independence at risk. But in 1990, a study had nursing home residents aged 86 to 96 train their legs for eight weeks: their strength more than doubled. Muscle responds to training at any age. Getting up from a chair without using your hands is already an exercise.