Podcast Summary: The 1000 Hours Outside Podcast

Episode 700: Mouth Breathing is Terrible | James Nestor, Breath
Host: Ginny Yurich
Guest: James Nestor, author of Breath
Release Date: February 4, 2026

Episode Overview

This milestone 700th episode invites James Nestor, acclaimed author of Breath, for a deep exploration of the hidden – and dramatic – health consequences of how we breathe, especially mouth vs. nose breathing. The conversation links mouth breathing to crooked teeth, ADHD, anxiety, sleep quality, endurance, and lifelong health, with practical advice for parents, teachers, and anyone hoping to improve their wellbeing. The episode is rooted in the 1000 Hours Outside ethos: real living, getting outdoors, and reclaiming health in a tech-heavy, indoor world.

Key Discussion Points & Insights

1. Why Indoor Air Quality and CO₂ Levels Matter

• CO₂ Buildup Indoors

  • Indoor CO₂ levels can be significantly higher than outdoor air, with detrimental effects on focus, cognition, and health.
  • Classrooms, offices, hotels, planes, and other public spaces often exceed safe CO₂ levels (e.g., up to 2500 ppm; safe outdoor baseline: ~400 ppm).

• Notable Stat: At 1500 ppm CO₂, 1 in every 40 breaths is someone else’s exhalation.

• Cognitive Impact: “A study at Harvard found 1500 parts per million showed a 55 percent decrease in cognitive tasks” – James Nestor (07:41).

• Easy Solutions: Crack windows, bring in CO₂ monitors (small, affordable devices), and push for better ventilation in schools.

  “The problem with so many schools today is the levels can be up to around 2,2500 parts per million. So this is so much higher than our bodies are accustomed to taking in this level of CO2...” (07:41 - James Nestor)

• Actionable Advice: Parents are encouraged to bring CO₂ monitors to schools, advocate for open windows, and build awareness.

• (05:38-13:29)

2. The Hidden Consequences of Mouth Breathing—Especially for Children

• Crooked Teeth, Small Mouths, and Airway Health

  • Almost 90% of kids develop some degree of jaw or mouth deformity due to modern diet and mouth breathing.
  • Ancestors had large mouths, straight teeth—modern diets and soft foods mean mouths develop smaller, causing crowding, crooked teeth, and restricted airways.
  • Bottle feeding, pacifiers, soft processed foods, and early tooth extractions all contribute.

  “The reason why 90% of us ... have some sort of crookedness in our teeth has nothing to do with teeth, has to do with our mouths growing smaller and smaller and smaller.” (13:49 - James Nestor)

• Early Functional Dental Interventions

  • Devices like Bioblock and Toothpillow, as part of orthotropics, expand the mouth and create better airways and facial profiles.
  • Traditional orthodontics often extracts teeth, making small mouths (and airways) even smaller—exacerbating problems.

  "If your kid has crooked teeth ... Don't make the mouth smaller. Talk to a dentist, a functional dentist, and find a way of expanding that mouth to the size it was supposed to have been." (21:10 - James Nestor)

• ADHD, Behavioral, and Sleep Issues

  • Sleep-disordered breathing (like mouth breathing and snoring) is strongly correlated with ADHD diagnoses and other behavioral issues.
  • 80% of kids with ADHD also have sleep-disordered breathing.
  • Simple checks: If you can hear your child breathing or snoring at night, it’s a red flag.

  “If you can hear them breathing while they're sleeping, there's a problem. If you can hear them snoring or choking on themselves, that's an emergency.” (30:49 - James Nestor)

  • Techniques like nasal breathing can lead to rapid, dramatic health improvements, including elimination of bedwetting and improvements in focus and behavior.

• (09:00–31:30)

3. Mouth Breathing vs. Nose Breathing: The Shocking Science

• James Nestor’s 10-Day Experiment

  • Nestor and a friend agreed to block their noses for ten days, becoming forced mouth-breathers. Rapid negative effects ensued: spikes in blood pressure, loss of focus, onset of snoring.
  • “Everything as advertised happened and it happened within a single day.” (33:02 - James Nestor)

• Nasal Breathing During Exercise

  • Mouth breathing during physical activity is inefficient; nose breathing increases oxygen usage and endurance.
  • Elite athletes and animals breathe through their nose, even at maximum effort.
  • It takes practice to shift, but performance and recovery improve dramatically.

  “If you think about an athlete ... if you are wasting energy breathing ... you are taking in all of this air, but it never makes it to the lungs ...” (35:53 - James Nestor)

• (33:02–37:40)

4. Expanding Lung Capacity: Impacts on Longevity, Scoliosis, and Chronic Conditions

• The Power of Proper, Full Breathing

  • Examples include Katerina Schroth using breathing methods to correct scoliosis and chorus teacher Carl Stough helping emphysema patients dramatically improve with exhale-focused breathwork.
  • “Schroth method” and “Buteyko breathing technique” are highlighted as powerful, accessible interventions.

  “She literally straightened her spine with breathing and then taught this to thousands and thousands of women throughout Germany. It's still taught today. It absolutely works.” (38:52 - James Nestor)

• Asthma Insights

  • Over-breathing through the mouth during an asthma attack worsens symptoms; slow, nasal breathing helps.

• (38:52–48:55)

5. Practical Tools & Notable Tips

• Appendix Goldmine

  • Nestor’s book contains a robust appendix: clear, pragmatic summaries of various breathing techniques with instructions.
  • The “Perfect Breath” is described; methods include 4-7-8 breathing, humming, breath holds, and more.
  • A free 7-day breath reset audio available on his website.

  “It’s the best appendix I’ve ever seen in any book … you go through every breathing method …” (48:55 - Ginny Yurich)

• The Science of CO₂ & Overbreathing

  • Our urge to breathe arises from CO₂ buildup, not oxygen deprivation.
  • Most people are habitual overbreathers, which can cause anxiety, chronic stress, and decreased oxygen delivery to cells.
  • Teaching breath awareness is crucial for anyone suffering from anxiety.

• (50:06–55:03)

6. James Nestor’s Publication Story: An Unexpected Bestseller

• Launching “Breath” During COVID

  • The book took far longer and cost far more than anticipated; just as it was to be published, COVID-19 shut down the world.
  • With bookstores shut, Nestor recorded the audiobook himself in a backyard shed using a $100 mic—accidentally creating a best-selling audio phenomenon.

  “We almost didn’t release it because … printing presses were stopped, but there were no bookstores open. I said, I’m completely hosed here.” (57:30 - James Nestor)

  “If you listen to that audiobook … you can hear maybe a trash truck cruising by … It was completely mad.” (60:41 - James Nestor)

• Breath became a surprise global hit, translated into 44 languages, with the audio edition topping charts—testament to the universal relevance of his discoveries.

• (56:56–62:41)

Notable Quotes & Moments

• On the urgency to change breathing awareness:

  “If you have a kid, you go into the kid’s room … If you can hear them snoring or choking on themselves, that’s an emergency.” (30:49 - James Nestor)

• On the lost wisdom and modern skepticism:

  “These things ... had been around since the 1800s. So that’s just the whole point … So many of these things are tried and true around the world and for a long time.” (18:38 - Ginny Yurich)

• On hope and lasting change:

  “You can influence the size and shape of our mouths and improve our ability to breathe at virtually any age.” (31:30 - Ginny Yurich, quoting Breath)

• On the book’s publication:

  “My head is just spinning. So completely random and unexpected.” (59:48 - James Nestor)

• On deep personal resonance:

  “Women in the ocean is my absolute earliest memory … I get in the ocean almost every day since then.” (63:53 - James Nestor, favorite outdoor childhood memory)

Timestamps for Key Segments

• CO₂ Indoors and Why Fresh Air Matters: 05:38–13:29
• Why Kids Struggle: Mouth Development, Orthotropics: 13:49–21:22
• Sleep Disordered Breathing, ADHD Link: 26:18–31:30
• Nestor’s Mouth Breathing Experiment: 33:02–37:40
• Expanding Lung Capacity, Scoliosis & Emphysema: 38:52–48:55
• Breathwork Tools, CO₂ Science: 50:06–55:03
• How “Breath” Became a Best-Seller: 56:56–62:41

Episode Takeaways

• Mouth breathing is NOT harmless; it causes a cascade of health and developmental problems.
• Nasal breathing builds health, improves sleep, focus, and even facial structure—at every age.
• Modern lifestyle and architecture create hidden hazards (CO₂/indoor air), easily remedied with awareness, advocacy, and small steps (open a window, use a monitor).
• Expanding your capacity for conscious, controlled breath has benefits so profound they can improve or even bypass chronic conditions like asthma and anxiety.
• Stories, not tips, stick: the historical, scientific, and personal tales in Breath make this a life-changing subject.

For more:

• Find James Nestor at mrjamesnestor.com
• Breath: The New Science of a Lost Art available wherever books are sold
• Free breathing resources and 7-day audio on his website
• Parents: check your kids’ sleeping, advocate for fresh air and functional dental care, and teach mindful breathing from an early age

“We are a culture of over-breathers... You learn so much. It’s just, thing after thing after thing.”
– Ginny Yurich (53:33)