CO₂ tolerance: why breath holds help

Here’s a surprise: when you hold your breath, the urge to breathe mostly comes from carbon dioxide building up, not from running low on oxygen.

Why that matters

Some people are very sensitive to rising CO₂. Their body sounds the alarm early, which can feel like breathlessness or anxiety even at rest. Gentle practice can make that alarm a little less jumpy.

A simple check

1. Sit quietly and breathe normally for a minute.
2. After a normal out-breath, pinch your nose and start a timer.
3. Stop at the first clear urge to breathe, not when you can’t hold any longer.

Note the number. Recovery breathing should feel calm, so if you gasp, you went too far. Check again in a month of slow nose breathing and see if it has changed.

Never practise breath holds in or near water, or while driving.

Breathing exercises are safe for most people, but they’re not medical advice. If you have a heart, lung or blood pressure condition, or you’re pregnant, check with your doctor before trying breath holds.