Improperly maintained cars make me almost as sad as improperly maintained horses. We destroy billions of dollars worth of cars each year collectively because of people not affording/otherwise failing to do maintenance. On the flip side, thoroughly maintaining them would tend to result in a glut of older, less efficient cars, so it's not a cut and dry issue.

Just wear a mask while you ride your horse, feed and brush them daily, you'll also feel better for doing so.