Sooner or later, everything's unhealthy for you

From The Economist, "Unhealthy showers:  The joy of Bathing:

IT HAS long been known that the air and water encountered by people in their daily lives are filled with all sorts of micro-organisms. Thankfully, most of these are benign and even the unsavoury ones can usually be washed down the drain without causing any harm.

Strikingly, in some of the samples they found high concentrations of a microbe known as Mycobacterium avium (a relative of the one that causes tuberculosis) which can cause respiratory illnesses. This is found in tap water, but remains harmless unless turned into an aerosol and inhaled—precisely what happens when bug-laden water is forced at high pressure through a showerhead. As the tiny particles are inhaled, they get into the lungs and can start an infection.

Is this cause for alarm? Not for healthy people, insists Dr Pace, but those with a compromised immune system or who are at risk of pulmonary diseases—the elderly, say—may want to take precautions. Cleaning showerheads with bleach will not do since the microbes will simply return with a fresh flow of water...