Typical Levels of Carbon Dioxide Gas CO₂ Normal Levels in Air Indoors & Outside

Toxicity of carbon dioxide gas, CO2 exposure limits
CARBON DIOXIDE - CO2 - separate article, topic home page
CO₂ POISONING SYMPTOMS - separate article
CO₂ HEALTH EFFECTS - separate article
CO₂ EXPOSURE LIMITS - separate article
TYPICAL CO₂ LEVELS
Questions & Answers about levels of CO₂ Carbon Dioxide gas found in and around buildings, CO₂ Carbon Dioxide gas hazards & exposure limits, and CO₂ measurement methods
References

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Typical CO2 - Carbon Dioxide Levels Indoors & Outside: this document discusses the typical or normal levels of carbon dioxide gas (CO₂) outdoors and inside buildings. We give references and explanation regarding Toxicity of Carbon Dioxide, based on literature search and search on Compuserve's Safety Forum by Dan Friedman. This is background information, obtained from expert sources. This text may assist readers in understanding these topics. However it should by no means be considered complete nor authoritative. Seek prompt advice from your doctor or health/safety experts if you have any reason to be concerned about exposure to toxic gases. Links on this page also direct the reader to carbon monoxide gas information in a separate document.

TYPICAL CO₂ LEVELS Indoors and Outside

Photograph of a Drager colorimetric gas detection tube used to measure carbon dioxide levels in the environment.

How to use gas detection tubes for measuring the level of various gases

The colorimetric gas detection tubes, here showing a tube made by Drager, are a relatively inexpensive way to test for the level of specific gases.

The tubes are quite accurate and can be selected and used down to very low concentrations of various gases, provided that a properly chosen and calibrated gas testing pump is used. In some cases for very precise measurements a correction factor needs to be applied for temperature at the time of measurement.

We use Drager tubes as well as another system of tubes and pump made for and sold through GasTec for testing indoor levels of specific gases.

What are the component gases that make up normal air and in what proportions or percentages do they ocur?

At sea level on earth, what is the composition of the air we breathe? That is, what gases make up normal outdoor air? How much CO₂ is in air? How much oxygen is in air? and how much nitrogen is in the earth's atmosphere? Here is the mix of gases in normal outdoor air.

The earth's atmosphere (measured close to ground level) is made up of 78.1% nitrogen, 20.9% oxygen, 0.9% argon, 0.03% carbon dioxide, and 0.04% other gases. Let's look at some typical CO₂ levels in both percentage and expressed in parts per million, which is how most instruments measure gas concentrations. [The mix of gases in air near some manufacturing facilities or in some cities may be a bit different.]

What are typical Carbon Dioxide levels in indoor and outdoor air?

Carbon dioxide CO₂ levels outdoors near ground level are typically 300 ppm to 400 ppm or 0.03% to 0.040% in concentration.
Carbon dioxide CO₂ levels indoors in occupied buildings are typically around 600 ppm to 800 ppm or 0.06% to 0.08% in concentration. You'll find this data in many indoor air quality articles and books and it's consistent with what we find typically in our own field measurements.
Carbon dioxide CO₂ levels indoors in an inadequately vented space with heavy occupation is often measured around 1000 ppm or 0.10% in concentration. I have measured levels around 1200 ppm in occupied basement offices in a hospital where the staff worked in an area which had no decent fresh air intake into their ventilation system. I

n 1989 I also measured 1200 ppm at chest height in the center of the sanctuary in a Jewish synagogue during the high holy days in a small New York city. I also observed people nodding off. We were never sure if it was a droning sermon, exhausted worshipers at the end of a long week, or the CO₂ level. But there was no doubt that we were not meeting recommended ventilation standards for that space.

The US EPA warns that indoor ventilation is inadequate at CO₂ levels of 1000ppm, [3] but for a more thorough discussion of toxicity of carbon dioxide see CO₂ POISONING SYMPTOMS and CO₂ HEALTH EFFECTS
Carbon dioxide levels above 1500 to 2000 ppm are likely to be reached only in unusual circumstances (being enclosed in an airtight closet for a long time) or in industrial workplace settings such as we cited above.

Carbon Dioxide CO₂ Sources in the Atmosphere & Carbon Dioxide CO₂ Level Changes as a Greenhouse Gas

According to the US EPA's overview data:

Carbon dioxide (CO₂) is emitted in a number of ways. It is emitted naturally through the carbon cycle and through human activities like the burning of fossil fuels.

Natural sources of CO₂ occur within the carbon cycle where billions of tons of atmospheric CO₂ are removed from the atmosphere by oceans and growing plants, also known as ‘sinks,’ and are emitted back into the atmosphere annually through natural processes also known as ‘sources.’ When in balance, the total carbon dioxide emissions and removals from the entire carbon cycle are roughly equal.

Since the Industrial Revolution in the 1700’s, human activities, such as the burning of oil, coal and gas, and deforestation, have increased CO₂ concentrations in the atmosphere. In 2005, global atmospheric concentrations of CO₂ were 35% higher than they were before the Industrial Revolution. For more information on CO₂ trends in the atmosphere, visit the page on Atmosphere Changes.

History of Levels of Carbon Dioxide CO₂ in the Atmosphere

Because CO₂ (carbon dioxide) is the principal component of greenhouse gases, CO₂ plays a crucial role in the extent and rate of global warming, scientists are interested in tracking changes in the level of CO₂ in the earth's atmosphere and also in the level of CO₂ in the earth's oceans (where that gase moves during periods of gobal cooling).

In practical effect, even before considerations of the chemical effects of changes in CO₂ in the atmosphere or oceans, this gas tracks not only global warming or cooling, but also changes in sea-level. (See FLOOD DAMAGE CLEANUP & REPAIR GUIDE for practical information about flood damage assessment & building repairs or floodproofing). The last period of significant global warming (and atmospheric surge in CO₂ occurred 120,000 years ago. [19]

In January 2013 the New York Times reported that at the dawn of the industrial revolution (ca 1760) the atmosphere typically contained 280 ppm of Carbon Dioxide (CO₂) while currently (in 2013) it is common to obtain outdoor Carbon Dioxide readings close to 400 ppm. [4]

In the Pleocine epoch (about 3,000,000 years ago) CO₂ levels have been estimated at about 400 ppm - a level scientists predict will be reached again (if not already by some measures) in the next few years. Relating CO₂ levels and rising sea levels, scientists currently (2013) are finding beach levels ranging from 33 feet to 295 feet above current sea levels (probably before correction for shifts in actual dry land movement up or down as well). [19][20][21]

According to the Times, 450 ppm of Carbon Dioxide CO₂ is considered a tipping point at which out-of-control acceleration of temperature rises occur due to the heat trapping effects of CO₂ and its effect as a greenhouse gas. [4]

Levels of carbon dioxide in the earth's atmosphere have in fact ranged widely over the planet's history. A peak CO₂ level [over 2000 ppm] appears to have been reached between 500 and 600 million years ago, dropping to close to current levels around 300 million years ago, and with a second surge to a much lower peak level around 100 million years ago.[8][10]

Pearson & Palmer, reporting on a study of the history of levels of carbon dioxide in the earth's atmosphere have reported:

We estimate CO₂ concentrations of more than 2,000 p.p.m. for the late Palaeocene and earliest Eocene periods (from about 60 to 52 Myr ago), and find an erratic decline between 55 and 40 Myr ago that may have been caused by reduced CO₂ outgassing from ocean ridges, volcanoes and metamorphic belts and increased carbon burial. Since the early Miocene (about 24 Myr ago), atmospheric CO₂ concentrations appear to have remained below 500 p.p.m. and were more stable than before, although transient intervals of CO₂ reduction may have occurred during periods of rapid cooling approximately 15 and 3 Myr ago.[5]

And Retallack has clearly indicated that

... For at least the past 300 Myr there is a remarkably high temporal correlation between peaks of atmospheric CO₂ .... and paleotemperature maxima ... . Large and growing databases on these proxy indicators support the idea that atmospheric CO₂ and temperature are coupled. [18]

Interestingly, while many scientists, including a thoughtful analysis by Mahli have pointed out that there are likely to be limits to tyhe amou7nt of casrbon storasghe possible in natural vegetaion, and that there is a significant potential to accelerate rather than brake global warming,[10][11][12][13][14][15][16][17], Kasting & Ackerman, reporting in1986 on modeling of possible effects on climate (including temperature) of high levels of carbon dioxide in the atmosphere, appeared unconvinced of the risk of development of runaway greenhouse gas conditions:

The early stratosphere should have been dry, thereby precluding the possibility of an oxygenic prebiotic atmosphere caused by photodissociation of water vapor followed by escape of hydrogen to space. Earth's present atmosphere also appears to be stable against a carbon dioxide-induced runaway greenhouse.[6]

Frequently Asked Questions (FAQs) about the typical levels of carbon dioxide found outdoors & inside buildings

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Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

[1] Dr. Roy Jensen, Department of Chemistry, Grant MacEwan College, Edmonton, AB for technical review and critique 8/23/07. Dr. Jensen notes that if we increase the CO₂ level in air in an enclosed space from its normal level of about 0.03% (we counted it as starting at 0) to a level of 1.4%, we obtain a corresponding decrease in the oxygen level from its normal level (at sea level) of about 20.9% down to 19.5%, for a 6.7% reduction in the amount of oxygen available. The amount of oxygen lost is 6.7 % (1.4/20.9 * 100 %). Our earlier version of this document was incorrect in this calculation.
[2] GAS EXPOSURE EFFECTS, TOXIC Toxic Gas Exposure Hazards and Test Protocols including links to our toxic gas exposure screening and gas testing protocols.
[3] US EPA - Mold Remediation in Schools and Commercial Building [Copy on file at /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
[4] Thomas L. Friedman, "The Market and Mother Nature", The New York Times, 9 January 2013, p. A21
[5] Paul N. Pearson1 & Martin R. Palmer, "Atmospheric carbon dioxide concentrations over the past 60 million years", Nature 406, 695-699 (17 August 2000) | doi:10.1038/35021000; Received 2 November 1999; Accepted 22 June 2000, retrieved 1/11/2013, original source: http://www.nature.com/nature/journal/v406/n6797/abs/406695a0.html
[6] James F. Kasting & Thomas P. Ackerman, "Climatic Consequences of Very High Carbon Dioxide Levels in the Earth's Early Atmosphere", Science, New Series, Vol. 234, No. 4782 (Dec 12, 1986), 1383-1385 - Abstract:
The possible consequences of very high carbon dioxide concentrations in the earth's early atmosphere have been investigated with a radiative-convective climate model. The early atmosphere would apparently have been stable against the onset of a runaway greenhouse (that is, the complete evaporation of the oceans) for carbon dioxide pressures up to at least 100 bars. A 10- to 20-bar carbon dioxide atmosphere, such as may have existed during the first several hundred million years of the earth's history, would have had a surface temperature of approximately 85 ° to 110 ° C. The early stratosphere should have been dry, thereby precluding the possibility of an oxygenic prebiotic atmosphere caused by photodissociation of water vapor followed by escape of hydrogen to space. Earth's present atmosphere also appears to be stable against a carbon dioxide-induced runaway greenhouse.
[7] Yadvinder Malhi, "Carbon in the Atmosphere and Terrestrial Biosphere in the 21st Century quick view", Philosophical Transactions: Mathematical, Physical and Engineering Sciences, Vol. 360, No. 1801, Astronomy and Earth Science (Dec. 15, 2002), pp. 2925-2945
[8] Robert A. Berner, "Atmospheric Carbon Dioxide Levels Over Phanerozoic Time", Science, Sept. 21, 1990: 249, 4795: ProQuest Medical Library Pg. 1382
[9] Yadvinder Mahli, "Carbon in the atmosphere and terrestrial biosphere in the 21st century, The Royal Society, 31 October 2002, 10.1098/rsta.2002.1098
[10] Gurney, K. R., Law, R. M., Denning, A. S. et al. 2002 Towards robust regional estimates of CO2 sources and sinks using atmospheric transport models. Nature 415, 626-630.
[11] Malhi, Y., Meir, P. & Brown, S. 2002 Forests, carbon and climate change. Phil. Trans. R. Soc. Lond. A 360, 1567-1591
[12] Malhi, Y. & Grace, J. 2000 Tropical forests and atmospheric carbon dioxide. Trends Ecol. Evol. 15, 332-337.
[131] Marland, G., Boden, T. A. & Andres, R. J. 2002 Global, regional and national fossil fuel CO2 emissions. In Trends: a compendium of data on global change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, US Department of Energy, Oak Ridge, TN.
[14] Phillips, O. L. (and 10 others) 1998 Changes in the carbon balance of tropical forests: evidence from long-term plots. Science 282, 439-442.
[15] Prentice, I. C. et al. 2001 The carbon cycle and atmospheric carbon dioxide. In Climate Change 2001: the scientific basis (ed. IPCC), pp. 183-237. Cambridge University Press.
[16] Schlesinger, W. H. 1997 Biogeochemistry. Academic. The Royal Society 2001 The use of land carbon sinks to mitigate climate change. Policy Docu- ment 10/01. (Available at http://www.royalsoc.ac.uk/files/statfiles/document
[17] Crutzen, P. J. 2002 The geology of mankind. Nature 415, 23.
[18] Gregory J. Retallack, "Carbon dioxide and climate over the past 300 Myr", The Royal Society, 15 March 2002, 10.1098 / rsta.2001.0960
[19] Justin Gillis, "How High Could the Tide Go?", The New York Times Science Section, 22 January 2013, p. D1, D6.
[20] M. E. Raymo, "The timing of major climate terminations", Paleoceanography, Volume 12, Issue 4, pages 577–585, January 1997.
Abstract
A simple, untuned “constant sedimentation rate” timescale developed using three radiometric age constraints and eleven δ¹⁸O records longer than 0.8 Myr provides strong support for the validity of the SPECMAP timescale of the late Quaternary [Imbrie et al., 1984]. In particular, the present study independently confirms the link between major deglaciations (terminations) and increases in northern hemisphere summer radiation at high latitudes and shows that this correlation is not an artifact of orbital tuning. In addition, the excess ice characteristic of late Quaternary “100-kyr” climate cycles typically accumulates when July insolation at 65°N has been unusually low for more than a full precessional cycle, or >21 kyr, and once established does not last beyond the next increase in summer insolation. Thus, the timing of the growth and decay of large 100-kyr ice sheets, as depicted in the deep sea δ18O record, is strongly (and semipredictably) influenced by eccentricity through its modulation of the orbital precession component of northern hemisphere summer insolation.
[21] Kenji Kawamura1, Frédéric Parrenin, Lorraine Lisiecki, Ryu Uemura, Françoise Vimeux, Jeffrey P. Severinghaus, Manuel A. Hutterli, Takakiyo Nakazawa, Shuji Aoki, Jean Jouzel, Maureen E. Raymo, Koji Matsumoto1, Hisakazu Nakata1, Hideaki Motoyama, Shuji Fujita, Kumiko Goto-Azuma, Yoshiyuki Fujii & Okitsugu Watanabe, "Northern Hemisphere forcing of climatic cycles in Antarctica over the past 360,000 years", (Letter), Nature 448, 912-916 (23 August 2007) | doi:10.1038/nature06015; Received 14 April 2007; Accepted 12 June 2007,
Excerpt: "These results support the Milankovitch theory that Northern Hemisphere summer insolation triggered the last four deglaciations"

Gases: Toxic gases, indoor exposure levels, testing, identification

A Toxic Gas Testing Plan: A Gas Sampling Plan for Residential and Commercial buildings lists some of the toxic indoor gases for which we test, depending on the building complaint and building conditions
CCSP, 2008: Analyses of the effects of global change on human health and welfare and human systems. A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research. [Gamble, J.L. (ed.), K.L. Ebi, F.G. Sussman, T.J. Wilbanks, (Authors)]. U.S. Environmental Protection Agency, Washington, DC, USA. Web search 08/28/2010, original source: http://nepis.epa.gov/
Gas Exposure Hazard Levels: for Toxic Gas Exposure to Ammonia, Arsine, Arsenic, Bromine, Carbon Dioxide, Carbon Monoxide, Hydride, Ozone - allowable exposure levels and hazard levels
Carbon Dioxide Gas Toxicity hazard level, poisoning symptoms, & testing
Health Effects of Carbon Dioxide - see "National Advisory Committee for Acute Exposure Guideline Levels (AEGLs) for Hazardous Substances; Proposed AEGL Values, Federal Register Document", http://www.epa.gov/EPA-TOX/2002/February/Day-15/t3774.htm note that these are proposed guidelines
Carbon Dioxide CO2: Geologic Sequestration Health Effects: "Vulnerability Evaluation Framework
for Geologic Sequestration of Carbon Dioxide", US EPA, EPA430-R-08-009, July 2008, web search August 2010,original source: http://www.epa.gov/climatechange/emissions/downloads/VEF-Technical_Document_072408.pdf
Carbon Dioxide CO₂: Geologic Sequestration, U.S EPA, web search 08/28/2010, original source:
http://www.epa.gov/climatechange/emissions/co2_gs_tech.html
- GTSP, 2006: Carbon Dioxide Capture and Geologic Storage: A Core Element of a A Global
  Energy Technology Strategy to Address Climate Change (PDF, 37 pp., 6.05 MB, About PDF).
  April 2006, JJ Dooley et al. Global Energy Technology Strategy Program (GSTP)
- IPCC, 2005: Special Report on Carbon Dioxide Capture and Storage, Special Report of the
  Intergovernmental Panel on Climate Change [Metz, Bert, Davidson, Ogunlade,
  de Coninck, Heleen, Loos, Manuela, and Meyer, Leo (Eds.)]. Cambridge University Press, The
  Edinburgh Building Shaftesbury Road, Cambridge CB2 2RU England
Carbon Monoxide Gas Toxicity hazard levels, poisoning symptoms, & testing
Fluorine, Its Compounds, and Air Pollution,: a Bibliography with Abstracts, US Environmental Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina 27711, December 1976. Web search 08/28/2010, original source: http://nepis.epa.gov.
NOTE: because the EPA's original source of this document in PDF format is damaged we have created a text image file, converted to a new PDF for readability.
Formaldehyde: US EPA. UFFI (Urea Formaldehyde Foam Insulation) was previously considered a hazard (formaldehyde outgassing). Subsequent research virtually closed concern regarding this material; however formaldehyde appears to remain a health concern for sensitive individuals.
Greenhouse Gas Overview: Carbon Dioxide: U.S. EPA, web search 08/28/2010, original source:
http://www.epa.gov/climatechange/emissions/co2.html
Nitrogen Oxides: Air Quality Criteria for Oxides of Nitrogen, Vol III of III, US EPA, EPA600/8-91/049cF, August 1993, web search 08/28/2010, original source: http://nepis.epa.gov [Large PDF 25MB]
Key chapters in this document evaluate the latest scientific data on (a) health effects of NOx measured ill laboratory animals and exposed human populatIOns and (b) effects of NOx on agricultural crops, forests, and ecosystems, as well as (c) NOx effects on visibility and nonbiological materials. Other chapters describe the nature, sources, distribution, measurement, and concentratiOns of NOx m the environment These chapters were prepared and peer reviwed by experts from various state and Federal government offices, academia, and private industry for use by EPA to support decision makIng regarding potentIal risks to public health and the enVIronment Although the document IS not intended to be an exhaustIve literature reVIew, It IS intended to cover all the pertinent literature through early 1993
Ozone Warnings - Use of Ozone as a "mold" remedy is ineffective and may be dangerous.
Sampling for gases in air such as VOC's, MVOC's, toxic chemicals, and combustion products.
Unfortunately no single test or tool can detect all possible building contaminants. We use methods and equipment which can test for common contaminants. If the identity of a specific contaminant is known in advance we can also test for a very large number of specific contaminant gases in buildings.
We use gas sampling equipment provided by the two most reliable companies in the world, Draeger-Safety's detector-tubes and Drager accuro� bellows pump, the Gastec� cylinder pump and detector-tube system produced by Gastec or Sensidyne, and we also use Sensidyne's Gilian air pump. For broad screening for combustibles and a number of other toxic gases and for leak tracing we also use Amprobe's Tif8850. All of these instruments, their applications, and sensitivities (minimum detectable limits) for specific gases are described in our Gas Sampling Plan online document.
Sulfur dioxide & other Oxides: Air Quality Criteria for Particulate Matter and Sulfur Oxides, Vol. III, US EPA, Environmental Criteria and Assessment Office, Research Triangle Park NC 27711, Dec. 1982, EPA-600/8/2-029c. Web search 08/26/2010, original source: http://nepis.epa.gov [large PDF]
Radon Gas U.S. EPA Radon level maps, web search 2005, original source: http://www.epa.gov/iaq/radon/zonemap/zmapp33.htm
"Table Z-1 Limits for Air Contaminants, 1910.1000 Table Z-1" OSHA standard for air contaminant limits (http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9992) - includes for CO2, Carbon dioxide.........| CAS No. 124-38-9 | 5000 ppm | 9000 mg/m3 limits for carbon dioxide as an air contaminant.
GAS EXPOSURE EFFECTS, TOXIC Toxic Gas Exposure effects, including links to toxic gas exposure screening and gas testing protocols.
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TYPICAL CO2 LEVELS Indoors and Outside