On a whole cut of beef, any bacteria, such as certain strains of E. coli, sit on the surface and die when the meat is seared. Grinding spreads them all the way through. That's why health authorities say ground beef should be cooked through, to about 70 °C (160 °F), especially for young children. And color is no guide: according to the USDA, more than one in four patties turns brown before it's safely cooked.
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.