France's Highway Code requires a safety gap of at least two seconds behind the vehicle in front. At 130 km/h (about 80 mph), that's roughly 72 metres. To help drivers judge it, some French motorway sections have white marks painted along the edge of the road, with a simple rule: 'one line, danger; two lines, safe'. Elsewhere, count 'two seconds' as the car ahead passes a fixed landmark.
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.