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Exposure Limits for Carbon Dioxide Gas - CO2 Limits
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InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.
Carbon Dioxide Exposure: this document discusses the exposure limits for carbon dioxide gas (CO2).
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.
IF YOU SUSPECT ANY BUILDING GAS-RELATED POISONING GO INTO FRESH AIR IMMEDIATELY
and get others out of the building, then call your fire department or emergency services for help.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
What are the Allowable Limits of CO2 EXPOSURE - Carbon dioxide exposure limits PEL and TLV set by OSHA and NIOSH
Carbon dioxide is regulated for diverse purposes but not as a toxic substance. The table below summarizes
- The U.S. EPA CO2 exposure limits: The U.S. EPA recommends a maximum concentration of Carbon dioxide CO2 of 1000 ppm (0.1%) for continuous exposure.
- ASHRAE standard 62-1989 recommends an indoor air ventilation standard of 20 cfm per person of outdoor air or a CO2 level which is below 1000ppm.
- NIOSH CO2 exposure limits: NIOSH recommends a maximum concentration of carbon dioxide of 10,000 ppm or 1% (for the workplace,
for a 10-hr work shift with a ceiling of 3.0% or 30,000 ppm for any 10-minute period). These are the highest
threshold limit value (TLV) and permissible exposure limit (PEL) assigned to any material.
- OSHA CO2 exposure limits: OSHA recommends a lowest oxygen concentration of 19.5% in the work place for a full work-shift exposure.
As we calculated above, for the indoor workplace oxygen level to reach 19.5% (down from its normal 20.9% oxygen level in outdoor air) by displacement
of oxygen by CO2, that is, to reduce the oxygen level by about 6% (1.4 absolute percentage points divided by 20.9% starting point = 0.06), the CO2 or carbon dioxide level would have to increase to about 1.4% 14,000 ppm.
- ACGIH exposure limit recommendations for Carbon Dioxide are as follows:
- CO2 TLV-TWA, 5,000 ppm (9000 mg/m3)
- CO2 TLV-STEL, 30,000 ppm (54,000 mg/m3)
- Quoting:
A TLV-TWA of 5000 ppm (9000 mg/m3) and a TLV-STEL of 30,000 ppm (54,000 mg/m3) are recommended for occupational exposure to carbon dioxide. The recommended values are intended to minimize the potential for asphyxiation and undue metabolic stress. The TLV-STEL is based on the short term, high carbon dioxide exposure studies that produced increased pulmonary ventilation rates. Sufficient data were not available to recommend Skin, SEN, or carcinogenicity notations. [1]
In summary, OSHA, NIOSH, and ACGIH occupational exposure standards are 0.5% CO2 (5,000 ppm) averaged over a 40 hour week, 0.3% (30,000 ppm) average for a short-term (15 minute) exposure [we discuss and define "short term exposure limits" STEL below], and
4% (40,000 ppm) as the maximum instantaneous limit considered immediately dangerous to life and health. All three of these exposure limit conditions must be satisfied, always and together.
What laws regulate carbon dioxide exposure levels?
Of the several industrial hygiene standards-setting groups in this country, the most important and/or most quoted are the National Institute for
Occupational Safety and Health (NIOSH), the Occupational Safety and Health Administration (OSHA), and the American
Conference of Governmental Industrial Hygienists (ACGIH) but these are recommended standards, not laws.
Standards promulgated by OSHA (called Permissible Exposure Limits or PELs) have the force of law. The other standards are advisory. However OSHA claims the power to force
compliance with NIOSH "Recommended Standards" if it chooses to do so. (The main advantage of ACGIH Threshold Limit Values
(TLVs) is that they are reviewed and updated annually; neither NIOSH nor OSHA updates its standards with any regular frequency.)
NIOSH limits on Carbon Dioxide Exposure: NIOSH's recommended CO2 exposure limit for 15 minutes is 3 percent. A CO2 level of 4 percent is designated by NIOSH as immediately dangerous to life or health.
OSHA limits on Carbon Dioxide Exposure: The U.S. Department of Labor Occupational Safety & Health Administration, OSHA, has set Permissible Exposure Limits
for Carbon Dioxide in workplace atmospheres at 10,000 ppm of CO2 measured as a Time Weighted Average (TWA) level of exposure and OSHA has set
30,000 ppm of CO2 as a Short-Term Exposure Limit (STEL). OSHA has also set a
Transitional Limit of 5,000 ppm CO2 exposure TWA. [OSHA's former limit for carbon dioxide was 5000 ppm as an 8-hour TWA.]
Definitions of Short Term Exposure Limits or STEL
What is the definition of "short term exposure" or "Short-Term Exposure Limit (STEL)"? The ACGIH has defined STEL as the
concentration (in this case of a gas in air) to which workers can be exposed continuously for a short period of time
without suffering from irritation, chronic or irreversible tissue damage, or narcosis of sufficient degree to increase the likelihood of accidental injury, impair self-rescue or materially reduce work efficiency.
What is a "short period"? and what is "short term exposure"?: The definition of "short period" is provided indirectly by ACGIH:
- If during an 8-hour work shift (and before it has ended) a worker is exposed to a substance in excess of the
threshold limit value, time weighted average exposure permitted exposure level for the entire shift, then that exposure has
exceeded the short term exposure limit or STEL.
- If a worker is exposed to more than four STEL periods during the course of an 8-hour work shift, with less than 60 minutes
between those exposure periods, then also that exposure has exceeded the STEL.
History of Threshold Limit Values TLVs for Carbon Dioxide Exposure Limits [1]
Historical TLVs for CO2 [In the U.S.] |
| Year |
Measure |
Limit |
| 1946-1947 |
MAC-TWA |
5000 ppm |
| 1948-present |
TLV-TWA |
5000 ppm |
| 1976-1985 |
TLV-STEL |
15,000 ppm |
| 1984 proposed |
TLV-STEL |
30,000 ppm |
| 1985-present |
TLV-STEL |
30,000 ppm |
Notes:
Source: ACGIH recommendations for CO2 .pdf [1][1b] |
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Frequently Asked Questions (FAQs) about the allowable exposure limits for elevated levels of CO2 - carbon dioxide
Question: OSHA CO2 exposure limits
I believe that you have interchanged 1.4% and 6% under OSHA above. This is very important as it means that an oxygen analyser will not alarm a dangerous concentration of CO2 . - Mark Crittendon 7/20/2012
Reply:
Thanks for looking closely at our CO2 exposure limit data, Mark.
Referring to the OSHA CO2 exposure limits, I have edited our text above to make the calculation of percentage points more clear: (1.4 absolute percentage points divided by 20.9% starting point = 0.06 - or 6% reduction in the CO2 level)
OSHA recommends a lowest oxygen concentration of 19.5% in the work place for a full work-shift exposure.
As we calculated above, for the indoor workplace oxygen level to reach 19.5% (down from its normal 20.9% oxygen level in outdoor air) by displacement of oxygen by CO2 , that is, to reduce the oxygen level by about 6% (1.4 absolute percentage points divided by 20.9% starting point = 0.06), the CO2 or carbon dioxide level would have to increase to about 1.4% 14,000 ppm.
Thank you for the careful read and the question. We are dedicated to making our information as accurate, complete, useful, and unbiased as possible: we very much welcome critique, questions, or content suggestions for our web articles. InspectAPedia is an independent publisher of building, environmental, and forensic inspection, diagnosis, and repair information for the public - we have no business nor financial connection with any manufacturer or service provider discussed at our website.
Question:
"In summary, OSHA, NIOSH, and ACGIH occupational exposure standards are 0.5% CO2 (5,000 ppm) averaged over a 40 hour week, 0.3% (30,000 ppm) average for a short-term (15 minute) exposure"
Sorry is this a mistake, or is there something obvious I am missing?
The TWA or TLV is 0.5%,
but the STEL is 0.3%;
the STEL would be a higher level than the TWA or TLV.
Is the upper limit for continuous 24 hour exposure now 0.1%?
Thank you,
John Brechin 11/13/2012
Reply:
John, in a typo there was a 3,000 that should have been 30,000. The ACGIH and other sources' recommended CO2 TLV-STEL is 30,000 ppm (54,000 mg/m3)
...
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
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[1] Carbon Dioxide, CAS Number: 124-38-9, TLV-TWA, 5000 ppm (9000 mg/m3), TLV-STEL, 30,000 ppm (54,000 mg/m3), from ACGIH and recommended by reader James Miller, USN Submarines, Ret. 3/20/2013. Copy on file as ACGIH recommendations for CO2 .pdf
Also
[1a] CDC Centers for Disease Control and Prevention, NIOSH Pocket Guide to Chemical Hazards, Carbon Dioxide, http://www.cdc.gov/niosh/npg/npgd0103.html, retrieved 3/20/2013
- [2] 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.
- [3] Thanks to careful reader Michael P. Doukas at USGS for correcting a decimal point error in our numbers on CO2 exposure limits - August 2010.
- 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
- [5] 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 Hazards and Test Protocols including links
to our toxic gas exposure screening and gas testing protocols.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
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