The surprising number of biological and psychological benefits of woodland air

Ever walked through a woodland and breathed in that unique smell of the fresh forest air and thought it feels pretty damn good? Well you are intuitively onto something…

Walking through woodlands offers a surprising number of biological and psychological benefits — many of which come from invisible natural compounds and microorganisms in the forest air and soil. Two key elements behind these effects are phytoncides and beneficial environmental bacteria.

Here’s how they work and why they matter:

1. Phytoncides: Nature’s Plant Defenders, Our Immune Boosters

Phytoncides are natural antimicrobial compounds released by trees and plants — especially evergreens like pine, cedar, spruce, and fir.

They help trees defend themselves against bacteria, fungi, and insects, but when humans breathe them in, they also have measurable effects on our bodies.

Benefits include:

• Immune System Support:
  Studies (notably in Japan on Shinrin-yoku, or “forest bathing”) show that inhaling phytoncides increases the number and activity of natural killer (NK) cells, a key part of our immune defense against viruses and even cancer cells.

• Reduced Stress Hormones:
  Phytoncides lower cortisol and adrenaline levels, calming the body’s stress response and supporting cardiovascular health.

• Improved Mood and Focus:
  These compounds interact with our nervous system to promote relaxation, lower anxiety, and enhance mental clarity.

• Better Sleep:
  Regular exposure is linked to improved sleep quality, partly due to reduced sympathetic nervous system activity (the “fight or flight” response).

2. Beneficial Bacteria: Microbial Companions That Shape Our Health

Woodlands are rich in diverse soil and air microbiota — harmless or beneficial bacteria, fungi, and spores that play a major role in regulating our immune system and mental health.

Benefits include:

• Microbiome Enrichment:
  Contact with soil, leaves, and forest air introduces a variety of non-pathogenic microbes that can help diversify your gut and skin microbiome, strengthening immune resilience.

• Reduced Inflammation and Allergies:
  Exposure to environmental bacteria such as Mycobacterium vaccae (common in healthy soil) has been shown to reduce inflammation and even improve mood by influencing serotonin levels — acting almost like a natural antidepressant.

• Immune Training:
  Interacting with diverse microbes “educates” the immune system, helping it distinguish between harmless and harmful triggers — reducing overreactions that cause allergies and autoimmune conditions.

• Mental Wellbeing:
  These microbial interactions are part of the “old friends hypothesis” — the idea that modern disconnection from nature has weakened our microbial exposure and contributed to rising rates of depression and immune dysregulation. Woodland exposure helps reverse this trend.

In Essence

Walking through woodland isn’t just peaceful — it’s a biological reset. You breathe in healing plant compounds, encounter immune-supportive microbes, reduce inflammation and stress, and even support your gut-brain axis.

It’s a quiet yet powerful way to strengthen both mind and body — through the chemistry and microbiology of the forest itself.

Have a ponder on all that next time you breathe in woodland air, and try and get more walks in woodlands to reap all the benefits…