Before the automobile, land transportation by means other than the human foot was chiefly by animal (by horse, mostly). (Before the railroad, which debuted in the early 19th century, the only means of land transportation was the human foot or animal power.) The emissions from horses and other transportation animals were themselves unpleasant and toxic. These emissions also attracted flies and other insects. Flies feasting on the mounds of transportation emissions that fouled city streets would spread bacteria from these emissions directly to humans and onto human food and into human drink.The automobile was the answer to these pollution issues. Not that the automobile dioesn't come with ts own problems, but as Boudreaux notes,
On rainy days the animal-’engine’ emissions would turn into a filthy slurry, much of which pedestrians tracked into the interiors of businesses and homes. When the weather was dry, the animal-’engine’ emissions would dry, much of it then circulating as dust that polluted the air.
[...] regardless of how toxic, dangerous, and unpleasant automobile emissions are, this toxicity and danger and unpleasantness must be compared with realistic alternatives before any policy-relevant assessments can be made. An unquestionably relevant alternative – at least for judging the course of history – is the state of transportation emissions prior to the advent of the automobile.Automobiles are our friend. So two cheers for the car!