Analysis / Healthy Country Air

The idea behind this trope comes from a discredited pre-germ theory idea known as Miasma Theory that disease was caused by bad air. This is where Malaria (Mal + aria = bad air) comes from, and is also the origin of some superstitions about opening windows at night, as well as the Swamps Are Evil trope (as swamps are source of bad smells). Obviously, we now know that disease isn't caused by bad-smelling air, but there might have been some Truth in Television in the idea behind this trope, as air pollution in 19th Century industrial cities was pretty unhealthy, and getting away from it could only help if you had lung issues.