{ "$schema": "https://json-schema.org/draft/2020-12/schema", "name": "OptiBreath indoor CO₂ exposure bands", "description": "Indoor carbon dioxide concentration bands with the reported effects on decision-making performance, anchored to published exposure conditions.", "version": "1.0.0", "url": "https://optibreath.space/co2-levels", "license": "https://creativecommons.org/licenses/by/4.0/", "licenseNote": "CC BY 4.0. Reuse freely with attribution to OptiBreath and a link to the source page.", "publisher": { "name": "OptiBreath", "url": "https://optibreath.space" }, "dateModified": "2026-08-27", "caveats": [ "The strongest effects come from controlled chamber studies with small samples. Several independent replication attempts have not reproduced them at the same magnitude.", "CO₂ may be partly a proxy rather than a pure cause. It correlates tightly with ventilation rate, bioeffluents and VOC accumulation, and some studies find effects only when those travel together.", "Effect sizes vary by task. Complex, open-ended, strategic work shows larger decrements than simple reaction-time or recall tasks — which is precisely the work our customers do.", "Individual response varies. The right way to use OptiBreath is to correlate your own environment against your own output, not to apply a population average to yourself.", "We report the indicative decision-making index as a directional guide derived from published effect sizes. It is not a clinical measurement and we do not present it as one." ], "units": { "concentration": "ppm", "note": "Parts per million by volume." }, "outdoorBaselinePpm": 425, "bands": [ { "id": "pristine", "label": "Baseline", "minPpm": 0, "maxPpm": 600, "severity": "optimal", "reportedEffect": "Effectively outdoor air. The reference condition against which every cognitive decrement in the literature is measured.", "typicalSetting": "Outdoors, or a room with windows open and cross-ventilation.", "indicativeDecisionScore": 100 }, { "id": "optimal", "label": "Optimal", "minPpm": 600, "maxPpm": 800, "severity": "optimal", "reportedEffect": "No decision-making decrement reported. This is the band OptiBreath is designed to hold you in.", "typicalSetting": "A well-ventilated office running at or above design airflow.", "indicativeDecisionScore": 97 }, { "id": "elevated", "label": "Elevated", "minPpm": 800, "maxPpm": 1000, "severity": "elevated", "reportedEffect": "The threshold zone. Approaching the 1,000 ppm condition at which Satish et al. first measured statistically significant declines in complex decision-making.", "typicalSetting": "A closed home office two hours into the working day.", "indicativeDecisionScore": 88 }, { "id": "degraded", "label": "Degraded", "minPpm": 1000, "maxPpm": 1400, "severity": "degraded", "reportedEffect": "At 1,000 ppm, six of nine decision-making measures fell moderately or substantially versus 600 ppm. Initiative and basic strategy were the most affected.", "typicalSetting": "A meeting room with the door shut and four people in it.", "indicativeDecisionScore": 74 }, { "id": "impaired", "label": "Impaired", "minPpm": 1400, "maxPpm": 2500, "severity": "critical", "reportedEffect": "Approaching the 2,500 ppm condition, where seven of nine measures fell and effect sizes on strategy and initiative were large.", "typicalSetting": "A packed conference room, or a bedroom with the door closed overnight.", "indicativeDecisionScore": 52 }, { "id": "critical", "label": "Critical", "minPpm": 2500, "maxPpm": null, "severity": "critical", "reportedEffect": "Large decrements across most decision-making measures, alongside the drowsiness, headache and loss of focus commonly reported at these concentrations.", "typicalSetting": "A sealed room at capacity with mechanical ventilation off or failed.", "indicativeDecisionScore": 34 } ], "indicativeDecisionScoreNote": "A directional index interpolated from the exposure conditions in Satish et al. (2012), relative to a 600 ppm baseline of 100. It is not a clinical measurement and must not be cited as one.", "guidelineThresholds": [ { "body": "ASHRAE", "region": "United States", "value": "~1,100 ppm indoors", "ppm": 1100, "basis": "Not a health limit. Standard 62.1 sets ventilation rates per person; a steady-state indoor concentration around 700 ppm above outdoors — roughly 1,100 ppm in practice — indicates those rates are being met. ASHRAE is explicit that CO₂ is an indicator of ventilation, not a contaminant of concern at these levels.", "source": "ANSI/ASHRAE Standard 62.1, Ventilation for Acceptable Indoor Air Quality", "url": "https://www.ashrae.org/technical-resources/bookstore/standards-62-1-62-2" }, { "body": "CIBSE", "region": "United Kingdom", "value": "1,000 ppm daily average", "ppm": 1000, "basis": "TM40 and the schools guidance treat a daily average at or below 1,000 ppm during occupied hours as the marker of adequate ventilation, with 1,500 ppm as the level requiring action.", "source": "CIBSE TM40: Health and Wellbeing in Building Services", "url": "https://www.cibse.org/knowledge-research/knowledge-portal/technical-memorandum-40-health-and-wellbeing-in-building-services" }, { "body": "REHVA", "region": "Europe", "value": "800 ppm for infection-risk control", "ppm": 800, "basis": "Post-2020 guidance recommends keeping occupied rooms below 800 ppm as a proxy for reducing airborne transmission risk, on the reasoning that CO₂ tracks rebreathed air fraction.", "source": "REHVA COVID-19 Ventilation Guidance", "url": "https://www.rehva.eu/activities/covid-19-guidance" }, { "body": "OSHA", "region": "United States", "value": "5,000 ppm, 8-hour TWA", "ppm": 5000, "basis": "An occupational exposure limit for CO₂ as a toxic gas, set an order of magnitude above anything an office reaches. Frequently misquoted as evidence that indoor CO₂ is harmless below it — the limit is about asphyxiation risk, not cognition.", "source": "OSHA Permissible Exposure Limit, 29 CFR 1910.1000", "url": "https://www.osha.gov/annotated-pels/table-z-1" }, { "body": "Global outdoor average", "region": "Worldwide", "value": "~425 ppm and rising", "ppm": 425, "basis": "The floor for any indoor measurement. It has risen roughly 100 ppm in sixty years, which slowly raises the baseline every indoor space starts from.", "source": "NOAA Global Monitoring Laboratory, Mauna Loa record", "url": "https://gml.noaa.gov/ccgg/trends/" } ], "sources": [ { "id": "satish-2012", "authors": "Satish, U., Mendell, M. J., Shekhar, K., Hotchi, T., Sullivan, D., Streufert, S., & Fisk, W. J.", "year": 2012, "title": "Is CO₂ an Indoor Pollutant? Direct Effects of Low-to-Moderate CO₂ Concentrations on Human Decision-Making Performance", "publication": "Environmental Health Perspectives, 120(12), 1671–1677", "doi": "10.1289/ehp.1104789", "url": "https://doi.org/10.1289/ehp.1104789", "stance": "supporting", "finding": "In a controlled chamber study using the Strategic Management Simulation battery, moderate to large decrements appeared in six of nine decision-making measures at 1,000 ppm and seven of nine at 2,500 ppm, relative to a 600 ppm baseline. Initiative and basic strategy showed the largest effects." }, { "id": "allen-2016", "authors": "Allen, J. G., MacNaughton, P., Satish, U., Santanam, S., Vallarino, J., & Spengler, J. D.", "year": 2016, "title": "Associations of Cognitive Function Scores with Carbon Dioxide, Ventilation, and Volatile Organic Compound Exposures in Office Workers (the COGfx Study)", "publication": "Environmental Health Perspectives, 124(6), 805–812", "doi": "10.1289/ehp.1510037", "url": "https://doi.org/10.1289/ehp.1510037", "stance": "supporting", "finding": "Across a double-blind, controlled exposure of 24 professionals over six days, cognitive function scores averaged 61% higher on Green building days and 101% higher on Green+ (enhanced ventilation) days than on Conventional days. Scores fell roughly 15% for each 400 ppm increase in CO₂." }, { "id": "allen-2018-field", "authors": "MacNaughton, P., Satish, U., Laurent, J. G. C., Flanigan, S., Vallarino, J., Coull, B., Spengler, J. D., & Allen, J. G.", "year": 2017, "title": "The impact of working in a green certified building on cognitive function and health", "publication": "Building and Environment, 114, 178–186", "doi": "10.1016/j.buildenv.2016.11.041", "url": "https://doi.org/10.1016/j.buildenv.2016.11.041", "stance": "supporting-field", "finding": "A field study of workers in green-certified versus non-certified buildings found 26.4% higher cognitive function scores and 6.4% higher sleep quality scores among occupants of green-certified buildings — moving the finding out of the chamber and into real offices." }, { "id": "macnaughton-2015", "authors": "MacNaughton, P., Pegues, J., Satish, U., Santanam, S., Spengler, J., & Allen, J.", "year": 2015, "title": "Economic, Environmental and Health Implications of Enhanced Ventilation in Office Buildings", "publication": "International Journal of Environmental Research and Public Health, 12(11), 14709–14722", "doi": "10.3390/ijerph121114709", "url": "https://doi.org/10.3390/ijerph121114709", "stance": "economic", "finding": "Doubling outdoor air ventilation rates was estimated to cost less than $40 per person per year while producing productivity gains valued at roughly $6,500 per person per year — a return of two orders of magnitude." }, { "id": "fisk-2019", "authors": "Fisk, W. J., Wargocki, P., & Zhang, X.", "year": 2019, "title": "Do Indoor CO₂ Levels Directly Affect Perceived Air Quality, Health, or Work Performance?", "publication": "ASHRAE Journal, 61(9), 70–77", "doi": null, "url": "https://www.osti.gov/biblio/1574073", "stance": "contested", "finding": "A review — co-authored by the lead author of the 2012 chamber study — concluding that the evidence for direct effects of CO₂ at concentrations below about 5,000 ppm is inconsistent, and that several attempts to replicate the strongest findings did not succeed." }, { "id": "zhang-2017", "authors": "Zhang, X., Wargocki, P., & Lian, Z.", "year": 2017, "title": "Effects of exposure to carbon dioxide and bioeffluents on perceived air quality, self-assessed acute health symptoms, and cognitive performance", "publication": "Indoor Air, 27(1), 47–64", "doi": "10.1111/ina.12284", "url": "https://doi.org/10.1111/ina.12284", "stance": "contested", "finding": "Exposure to pure CO₂ at 3,000 ppm produced few effects on cognitive performance, while exposure to bioeffluents at the same CO₂ level increased reported health symptoms and reduced motivation — suggesting CO₂ may act partly as a proxy for everything else people exhale." } ] }