In 1953, the small Rocket Chemical Company in San Diego set out to create a product that would push away moisture and prevent corrosion. It took 40 attempts to get the recipe right, hence the name WD-40: Water Displacement, 40th formula. It was first used to protect the outer skin of Atlas missiles before finding its way into garages. Its core job is still driving out water, not long-term greasing.
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.