From : The Doctor's Dilemma by GB Shaw 1913:

"The simplest way to kill most microbes is to let the sun shine on them.....  But doctors instinctively  avoid all facts that are reassuring, and eagerly swallow those that make it a marvel that anyone could possibly survive  three days in an atmosphere  consisting mainly of countless pathogenic germs.  They conceive microbes as immortal until slain .. by a duly qualified medical men.... people are adjured.... not to throw their microbes into the sunshine, but to collect them carefully in a handkerchief; shield the handkerchief from the sun in the darkness and warmth of the pocket; and send it to a laundry to be mixed up with everybody else's handkerchiefs..."