How we write and review our guides

Every guide on this site is written and edited by the BreathTestOnline Editorial Team, a small independent group. We are not a medical practice and we do not sell devices, supplements, coaching, or diagnoses. The site is funded by advertising, which is why we publish our privacy policyand why we will never sell or accept payment for a specific result, ranking, or recommendation.

Our explanations rest on the physiology that is well established in the literature and taught in respiratory medicine: the urge to breathe is driven primarily by rising carbon dioxide rather than falling oxygen; slow-paced breathing at roughly six breaths per minute with an extended exhale reliably lowers heart rate and raises heart-rate variability; breath-hold time reflects CO₂ tolerance and breath economy far more than lung size.

Where we cite specific studies — for example the Stanford work on cyclic sighing, or physiological-sigh research on vagal tone — we name the finding and the year rather than implying a single definitive answer. Where the evidence is genuinely mixed or thin, we say so instead of overstating it.

We also use our own timer data only as illustrative context, never as evidence of a medical relationship between a hold time and a health outcome. We do not have access to — and do not collect — your results; they stay in your browser.

Breath-holding carries a real, if small, risk. Every guide and every part of the timer carries the same rules, and we do not soften them for engagement:

• Always sit down. Never test standing, driving, or while walking.
• Never in or near water. Shallow-water blackout is the specific hazard of breath-hold practice, and it is usually preceded by hyperventilation.
• Never hyperventilate first. Over-breathing suppresses the urge to breathe and is the main cause of loss of consciousness in water.
• Stop at the first sign of dizziness, tingling, or visual change. Pushing through lightheadedness is the mistake that turns a safe game into an ambulance call.
• See a clinician before training if you are pregnant, or have a heart or lung condition, epilepsy, or high blood pressure.

• We do not diagnose, treat, or claim to prevent lung disease, COPD, asthma, or any other condition.
• We do not present breath-hold time as a medical test. It is a coordination and CO₂-tolerance benchmark — fun, comparable to yourself over time, and not a measure of lung health.
• We do not quote a figure as "normal" without saying it is a rough range across a broad population, since individual variation is large.
• We do not recommend supplements, devices, or paid programs.
• We do not use fear-based framing about your lungs to drive clicks.

Guides carry a publication date and a last-updated date, both taken from a single content record so the date you see on the page, the structured data, and the sitemap cannot disagree. When we correct a factual or safety error we update the date rather than quietly editing, so you can tell what changed.

If you are a qualified professional and something here is wrong, incomplete, or unsafe, we want to hear it. Contact us and cite the source you are objecting to — we give corrections priority over new content. We do not remove a page for being unhelpful, but we will remove or rewrite anything that misleads.

This is a free hobby project about breathing, written carefully but without clinical backing. Take the timer's numbers as a fun benchmark, take the safety rules seriously, and take anything health-related to someone qualified to advise you.