In 1913, German chemist Otto Röhm patented a surprising idea: using digestive enzymes taken from slaughterhouse pancreases to lift stains. His soaking agent, Burnus, hit the market the following year. Today's detergents contain enzymes made by microorganisms: proteases for blood or egg, amylases for starch, lipases for grease. Because they work at low temperatures, they make 30 °C (86 °F) washes possible.
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.