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.

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.

The automobile – in addition to all of the other enormous benefits of this remarkable product (see also here) – makes our world cleaner.

It’s true, of course, that the automobile has its own emissions – emissions which, were we residents of paradise, we’d eliminate with the snap our fingers. But 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.

So on this Earth Day, I will be especially cognizant of celebrating the unprecedent cleansing powers of capitalism (just as I did three years ago when I helped my then-sixth-grader son with a homework assignment).