In 2017, German researchers analyzed 14 used kitchen sponges. They measured densities of up to 54 billion bacteria per cubic centimeter, levels usually found only in fecal samples. Microwaving a sponge kills the vast majority of germs, but the survivors grow back fast. The same team recommends replacing it every week or two instead, and demoting the old one to garden duty.
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.