What mountain air does, and doesn’t

People come back from the Rockies saying they can breathe again. Some of that is real, and some of it is story. This piece tries to tell them apart.

What the air is, physically

Mountain air is thinner, not richer. At any height, air is about 21 percent oxygen. What changes is the pressure: the higher you go, the fewer molecules in each breath, so each breath carries a little less oxygen. Calgary sits at roughly 1,050 metres. Banff is at about 1,400. At those heights most people notice little; some notice that stairs make them breathless a little sooner. So this is not oxygen-rich air. It is often cleaner and cooler, and on a good day very quiet. Not always. Wildfire smoke can fill a mountain valley as easily as a city street, which is why we keep a separate page on breathing in smoke season.

What time in nature is associated with

There is real research on time in green and wooded places, and it is worth reading carefully.

In a Japanese field study across 24 forests, with 280 young adults, researchers measured people after a walk in a forest and after a walk in a city. On average, the forest walkers showed lower stress-related measures, such as cortisol and pulse rate, and a pattern that points toward the settling side of the nervous system. Studies like this grew up around shinrin-yoku, “forest bathing”, a phrase Japan’s forestry agency introduced in the early 1980s. The participants were young adults, and the exposure was brief.

A larger 2018 review pooled 143 studies of green space. On average, people with more time in or near green space tended to have a lower resting heart rate and lower cortisol, among other small differences. These are associations, mostly from observational data, and the authors note that several results are limited by study quality and by large differences between studies. People who spend more time outdoors also tend to differ in other ways.

Much of what we credit to the air may belong to the walk, the daylight, the movement, the company, and the absence of a to-do list. We do not need to separate these things in order to enjoy them. But it is honest to say that we cannot separate them.

What it does not do

The popular story says that mountain air, waterfalls and forests are rich in negative ions that lift the mood. A 2013 review looked at 33 experiments on air ions. It found no consistent effects on mood, anxiety, relaxation, sleep or comfort. When five studies of negative ions and depression scores were pooled, lower scores were linked with negative ions, especially at the highest exposure levels in the experiments, and the authors themselves call for more research. That says little about a walk on a ridge.

Mountain air will not carry you through a hard year, or stand in for medical care. It is air.

If you go, go slowly. Breathe through the nose on the way up, and let the out-breath run long at the top. We have a five-minute practice called Roam the ridge, which needs no mountain at all: you walk a ridge in your mind, and the view moves forward only as you breathe out.

When did you last breathe all the way out at the top of a hill? Try it this weekend.