The following is adapted from Chapter 4 of the author’s book “Fear of a Microbial Planet: How a Germophobic Safety Culture Makes Us Less Safe.”
When cholera broke out in London in the first half of the nineteenth century, experts were quick to place the blame on miasma—the accumulation of toxic gases and odors within the atmosphere they claimed was responsible for a host of human misery.
In hindsight, it’s rather easy to explain their ignorance, as London in the early nineteenth century was a foul, fetid place that had exploded in population, yet had retained the lack of sanitation of earlier medieval times. Huge, crowded slums provided the perfect culture media for human infectious diseases. Urine and feces from chamber pots were unceremoniously dumped into alleys or leaky cesspits—there were no sewers of any kind. Trash was strewn everywhere, attracting disease-carrying rats and other vermin….