Raw rice often carries spores of Bacillus cereus, a bacterium that survives cooking. If cooked rice sits for hours at room temperature, the spores germinate and some strains produce a toxin that shrugs off heat: reheating won't destroy it. The result can be vomiting within hours of the meal. France's food safety agency advises cooling leftovers quickly and refrigerating them within two hours.
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.