The air really is different
Where moving water breaks up — at waterfalls, surf and rapids — air picks up a negative charge (the Lenard effect). Field surveys report much higher negative-ion counts at waterfalls and, to a lesser degree, in forests than in city air. See the chart.
Time in nature is linked to wellbeing
- A large English survey (about 19,800 people) found that those who spent at least 120 minutes a week in nature were more likely to report good health and wellbeing. It is an association from self-reported data. (summary of White et al., 2019)
- Meta-analyses of “forest bathing” report lower blood pressure and stress markers in forest settings than in comparison settings, mostly in small, short studies. (Ideno et al., 2017; Park et al., 2010)
Where might ions fit in?
A walk in the woods brings many things at once: greenery, light, birdsong, gentle exercise, clean air — and ions. Researchers are still working out which of these matter most.
Indoors, controlled trials of high-density ionization have found benefits for winter depression, and early studies are looking at focus and cleaner air. Whether ions contribute to the lift people feel outdoors hasn’t been tested directly. It is an open, interesting question.
Easy ways to bring more nature in
- Short, regular time outdoors: a walk in a park counts.
- Looking at trees and water, and listening to natural sounds. Simulated nature (images, sounds, VR) has shown small, short-lived mood benefits in studies, smaller than the real thing.
- Open windows where you can, and get outside for a break.
These are associations with wellbeing, not treatments. If you’re struggling with low mood, talk to a doctor.