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.

What are the Allowable Limits of CO₂ Exposure - Carbon dioxide PEL & TLV by ACGIH, OSHA & NIOSH

Notes to the table above:

1 Adapted & expanded (to add ppm) from EPA, APPENDIX B-I ACUTE HEALTH EFFECTS of CARBON DIOXIDE [PDF] cited below. Some of this data from table B1 cited in the EPA table in turn cites Compessed Gas Association 1990.

2. ( Erdmann 2002) cited below

3. NCCEH cited below citing in turn (Health Canada 1987)

Carbon dioxide is regulated for diverse purposes but not as a toxic substance. Nevertheless extensive research has documented health and performance impacts of exposure to carbon dioxide at various levels.

• 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]
• 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.
• U.S. EPA CO₂ carbon dioxide exposure: EPA identifies indoor air quality or IAQ as a top building health concern; studies report cognitive impairment in people working in indoor CO₂ concentrations over 1,000 ppm in studies discussing SBS Sick Building Syndrome; some of these studies are provided by the U.S. EPA. A maximum concentration of Carbon dioxide CO₂ of 1000 ppm (0.1%) for continuous exposure is suggested. (Erdman 2002)

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:

1. 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.
2. 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]

Notes to the Table Above

Source: ACGIH recommendations for CO₂

Carbon Dioxide CO₂ Exposure Limit Sources & Research

• ACGIH recommends an 8- hour TWA Threshold Limit Value (TLV) of 5,000 ppm and a Ceiling exposure limit (not to be exceeded) of 30,000 ppm for a 10-minute period. A value of 40,000 is considered immediately dangerous to life and health (IDLH value).
• [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
• CCOHS Exposure Guidelines for Residential Indoor Air Quality [PDF] Health Canada, (1989 Rev), retrieved 2019/11/02 original source: http://www.hc-sc.gc.ca/ewh-semt/alt_formats/hecs-sesc/pdf/pubs/air/exposure-exposition/exposure-exposition-eng.pdf
  
  Excerpts:
  
  In several studies, comfort factors have been correlated with carbon dioxide concentrations. Collectively, these studies suggest that carbon dioxide concentrations above 1800 mg/m3 (1000 ppm) are indicative that there is an inadequate supply of fresh air, although complaints have been documented at concentrations as low as 1100 mg/m3 (600 ppm).
  
  However, from a review of the direct physiological effects of exposure to carbon dioxide, as opposed to subjective symptoms, a higher maximum exposure concentration is recommended (see Section 4.A.2).
  
  It must be noted that these studies were conducted in buildings with mechanical ventilation systems and with occupancy rates quite different from those of residences. Moreover, the effects observed are probably not attributable to the presence of elevated concentrations of carbon dioxide, but rather to undesirable concentrations of other substances that result from inadequate ventilation, and for which carbon dioxide provides a suitable surrogate parameter.
  
  Therefore, caution must be used in interpreting carbon dioxide concentrations as a general indication of residential indoor air quality.
• CCOHS. 1990. Carbon Dioxide Chemical Infogram. Canadian Center for Occupational Health and Safety, Hamilton, Ontario. October
• [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/
• Compressed Gas Association. 1990. Handbook of Compressed Gases, Third Edition. Compressed Gas Association, Chapman and Hall.
• Consolazio, W.V.; Fisher, M.B.; Pace, N.; Pecora, L.J.; Pitts, G.C.; Behnke, A.R. 1947. Effects on man of high concentrations of carbon dioxide in relation to various oxygen pressures during exposures as long as 72 hours. Am. J. Physiol. 151:479-503.
• Erdmann, Christine A., Kate C. Steiner, and Michael G. Apte, INDOOR CARBON DIOXIDE CONCENTRATIONS AND SICK BUILDING SYNDROME SYMPTOMS IN THE BASE STUDY REVISITED: ANALYSES OF THE 100 BUILDING DATASET [PDF] Proceedings: Indoor Air 2002, retrieved 2019/11/02 original source: www.epa.gov/sites/production/files/2014-08/documents/base_3c2o2.pdf
  
  ABSTRACT
  In previously published analyses of the 41-building 1994-1996 USEPA Building Assessment Survey and Evaluation (BASE) dataset, higher workday time-averaged indoor minus outdoor CO2 concentrations (dCO2), were associated with increased prevalence of certain mucous membrane and lower respiratory sick building syndrome (SBS) symptoms, even at peak dCO2 concentrations below 1,000 ppm. For this paper, similar analyses were performed using the larger 100-building 1994-1998 BASE dataset.
  
  Multivariate logistic regression analyses quantified the associations between dCO2 and the SBS symptoms, adjusting for age, sex, smoking status, presence of carpet in workspace, thermal exposure, and a marker for entrained automobile exhaust. Adjusted dCO2 prevalence odds ratios for sore throat and wheeze were 1.17 and 1.20 per 100-ppm increase in dCO2 (p <0.05), respectively.
  
  These new analyses generally support our prior findings. regional differences in climate and building design and operation may account for some of the differences observed in analyses of the two datasets.
• EPA, APPENDIX B-I ACUTE HEALTH EFFECTS of CARBON DIOXIDE [PDF] retrieved 2019/11/02 original source: https://www.epa.gov/sites/production/files/2015-06/documents/co2appendixb.pdf
  
  Appendix B presents an overview of the acute health effects associated with carbon dioxide.
  
  Part I discusses the dangerous, lethal effects of carbon dioxide at high exposure concentrations. The minimum design concentration of carbon dioxide for a total flooding system is 34 percent (340,000 ppm). When used at this design concentration, carbon dioxide is lethal.
  
  Part II discusses the potentially beneficial effects of carbon dioxide at low exposure concentrations and the use of added carbon dioxide in specialized flooding systems using inert gases.
• EPA 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 - 2019/11/02 note that these proposed guidelines are no longer found at this US EPA web page link.
• NCCEH, Carbon Dioxide in Indoor Air, National Collaborating Centre for Envrionmental Health, Retrieved 2019/11/02 original source: http://www.ncceh.ca/documents/practice-scenario/carbon-dioxide-indoor-air
  
  Excerpt:
  
  The lowest level at which a human health effect (i.e. acidosis) has been observed in humans is 7,000 ppm, and that only after several weeks of continuous exposure in a submarine environment.
  
  In its 1987 Exposure Guidelines for Residential Indoor Air Quality,2 Health Canada set an exposure limit of 3,500 ppm to protect against such undesirable adaptive changes to acidosis, in particular calcium release from bones.
  
  The occupational limits for CO2 recommended by the American Conference of Governmental Industrial Hygienists (ACGIH) are 5000 ppm (TLV-TWA) and 30,000 ppm (TLV-STEL),3 based on the direct effects on acidification of the blood.
• OSHA TABLE Z-1 LIMITS FOR AIR CONTAMINANTS, 1910.1000 TABLE Z-1 [PDF] 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. - accessed 2019/11/02 original source: https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TABLEZ1
• US EPA GREENHOUSE GAS OVERVIEW: CARBON DIOXIDE [PDF] U.S. EPA, web search 08/28/2010, original source: http://www.epa.gov/climatechange/emissions/CO₂ .html
  
  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.
• USDA, CARBON DIOXIDE HEALTH HAZARD INFORMATION SHEET [PDF] U.S. Department of Agriculture, retrieved 2019/11/02 original source: https://www.fsis.usda.gov/wps/wcm/connect/bf97edac-77be-4442-aea4-9d2615f376e0/Carbon-Dioxide.pdf?MOD=AJPERES
• U.S. EPA, EPA Fact Sheet: CARBON POLLUTION STANDARDS FINAL LIMITS ON CARBON POLLUTION FROM NEW, MODIFIED AND RECONSTRUCTED POWER PLANTS [PDF] (2013) U.S. E nvironmental protection agency, original source: archive.epa.gov/epa/sites/production/files/2015-11/documents/fs-cps-overview.pdf now considered an "archived document" by the epa, that you can also download here at inspectapedia
  
  Excerpt: "it is an emission limit of 1,000 pounds of co2 per megawatt-hour on a gross-output basis (lb co2/mwh-gross). this standard applies to all sizes of base load units. non-base load units need to meet a clean fuels input-based standard."
• See additional citations at REFERNCES below

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2021-02-25 - by (mod) -

@Tech, Thank you very much for taking time to write about the decimal place error in the chart above. I appreciate all the editing help we can get.

I have edited and so corrected the error; you may need to clear your browser cache to see the updated page.

On 2021-02-25 by Tech

The first chart on this page [https://inspectapedia.com/hazmat/Carbon%20_Dioxide_Exposure_Limits.php#QA] has an error in the table. [Table B-11 & B-21 Acute & Other Health Effects of High Concentrations of Carbon Dioxide]
The bottom left box of the matrix has an incorrect value.
It has: 0.5 ppm
It should be: 0.05 ppm
Compare to values above and the error becomes apparent.

On 2019-11-02 by (mod) - What is the reference for the EPA limit (recommendation) of 1000 ppm?

Matthew:

You are right that the U.S. EPA has not set an explicit exposure limit for carbon dioxide but the agency does cite research and also cites other CO2 exposure standards and limits. I've updated and clarified that point in the article above. Thank you for the helpful query.

The U.S. EPA document discussing sick building syndrome or SBS as I'll cite below gives us:

• U.S. EPA, original source: CA Erdmann, C.A., KC Steiner, and MG Apte, INDOOR CARBON DIOXIDE CONCENTRATIONS AND SICK BUILDING SYNDROME SYMPTOMS IN THE BASE STUDY REVISITED: ANALYSES OF THE 100 BUILDING DATASET [PDF] Proceedings: Indoor Air 2002, retrieved 2019/11/02 original source: https://www.epa.gov/sites/production/files/2014-08/documents/base_3c2o2.pdf
  
  ABSTRACT
  In previously published analyses of the 41-building 1994-1996 USEPA Building Assessment Survey and Evaluation (BASE) dataset, higher workday time-averaged indoor minus outdoor CO2 concentrations (dCO2), were associated with increased prevalence of certain mucous membrane and lower respiratory sick building syndrome (SBS) symptoms, even at peak dCO2 concentrations below 1,000 ppm.
  
  For this paper, similar analyses were performed using the larger 100-building 1994-1998 BASE dataset. Multivariate logistic regression analyses quantified the associations between dCO2 and the SBS symptoms, adjusting for age, sex, smoking status, presence of carpet in workspace, thermal exposure, and a marker for entrained automobile exhaust
  
  . Adjusted dCO2 prevalence odds ratios for sore throat and wheeze were 1.17 and 1.20 per 100-ppm increase in dCO2 (p <0.05), respectively. These new analyses generally support our prior findings. regional differences in climate and building design and operation may account for some of the differences observed in analyses of the two datasets.
  
  Download this paper in links given in the article above on this page.
• U.S. EPA,- source: u.s. epa, "epa fact sheet: carbon pollution standards final limits on carbon pollution from new, modified and reconstructed power plants" [pdf] - u.s. environmental protection agency, (2013) original source: archive.epa.gov/epa/sites/production/files/2015-11/documents/fs-cps-overview.pdf now considered an "archived document" by the epa, that you can also download here at inspectapedia in links given above on this page
  
  Excerpt:
  "it is an emission limit of 1,000 pounds of co2 per megawatt-hour on a gross-output basis (lb co2/mwh-gross). this standard applies to all sizes of base load units. non-base load units need to meet a clean fuels input-based standard."
  

On 2019-10-29 by Matthew

What is the reference for the EPA limit (recommendation) of 1000 ppm?

On 2018-09-20 by (mod) - 300 - 500 ppm CO2 in outdoor air

Thank you for the comment, Ed.

Normally in outdoor air the CO2 level ranges between 300 or 0.03% concentration to 500 ppm or 0.05% concentration. I have on occasion measured higher concentrations of carbon dioxide in outdoor air, for example near a busy roadway.

Your citation of the amount of H2O or water in air is a different measure entirely

On 2018-09-19 by Ed Golla 1 to 2% H2O in ambient air ?

Don't forget to include the 1 to 2% H2O that is normally present in ambient air.

On 2017-10-06 by Wm.

Wood pellet storage. Our monitors are set to go off at 35ppm. We are told osha standard is 50ppm. If monitor reads 64ppm is it safe to work in?

On 2016-01-18 1 by Anonymous - easier way to come up with the amount of CO using electrochemical sensors

An easier way to come up with the amount of CO for this problem is as follows.
The easiest way that most of us will measure O2 is with an electrochemical sensor. So lets do some math.

An electrochemical sensor is reading O2. O2 is around 20% of fresh air. So the sensor is reading around 1/5 of the atmosphere.

When CO2 is introduced it is not just displacing O2, it is displacing the atmosphere.

We are reading CO2 in ppm. So, 1 million ppm = 100%, 500,000 = 50%, 100,000 = 10%, 10,000 = 1%.

If your O2 sensor goes from 20.9 to 19.5 you would assume that 14,000 ppm of CO2 was there by the sentence above.

BUT, remember the O2 sensor is reading something that is only around 1/5 of the atmosphere. It is not an atmosphere sensor but an O2 sensor. 1/5 has been entered in the formula by this and must be factored in.

Take your 14,000ppm and times it by 5. You now have 70,000ppm

At work I just do it like this.

Every 1/10 that the O2 sensor drops, is equal to 5000ppm.

Example - O2 sensor reading of 20.9 goes down to 20.5. A difference of .4. Take the 4 X 5000 = 20,000ppm of CO2 is there.

On 2015-10-22 by Henry Baxter - calculation of CO2 increase to create an O2 deficiency is incorrect.

Your calculation of CO2 increase to create an O2 deficiency is incorrect.

To reduce your O2 from 20.9% to 19.5% (by 1.4%) you have to account for the dilution of N2 in air as well as O2

A typical N2/O2 ratio of fresh air is 3.77:1, i.e. n2 is 3.77 times more abundant than O2 in air.

Assuming there is dilution only (i.e. no consumption of O2 or other gasses) For a given O2 % you can work out the N2% by multiplying O2%x3.77

e.g. 19.5% O2 would have 3.77 x 19.5 = 73.5% N2 associated with it.

19.5 + 73.5 = 93% i.e. the air fraction makes up 93% of the total.

If the sole diluting agent is CO2 then the balance (7%) is the concentration of CO2 required to get less than 19.5% O2.

Dangerous Levels of CO₂ Encountered Outdoors?

Reader Question: 11/25/2014 Rox said:

What is a dangerous level of CO₂ outdoors ? I know that we are at about 300-400ppm, at what point it is too dangerous to go outside because of the level on CO₂ ?

Reply:

Rox

At our home page for Carbon Dioxide information (CO₂ ) you'll find text on the toxicity of this gas.

See CARBON DIOXIDE - CO₂

including comparing indoor with outdoor carbon dioxide levels. It would be unlikely for you to encounter toxic levels of CO₂ outdoors unless the outdoor area were somehow enclosed on all sides, in still air and was receiving a source of high-concentration of carbon dioxide gas or unless the area is one exposed to high levels of combustion such as Naeher (2000).

In Naeher's research CO₂ served principally as an easy-to-measure indicator of other more problematic air quality problems such as high levels of particulates associated with open fires, wood burning stoves, and in some cases gas stoves. In other words, you'd be standing in a smoky area.

The outdoor level of carbon dioxide is relatively constant with occasional peaks

You will find that most research on hazards of gases in outdoor air address carbon monoxide (CO) not carbon dioxide (CO2) - see Curtis (2006) or Thompson (1973).

Outdoor Air Quality and Carbon Dioxide CO₂ Levels

Some interesting research that addresses you outdoor air quality question includes the following authors who discuss indoor and outdoor CO2 levels.

• Baek, Sung-Ok, Yoon-Shin Kim, and Roger Perry. "Indoor air quality in homes, offices and restaurants in Korean urban areas—indoor/outdoor relationships." Atmospheric Environment 31, no. 4 (1997): 529-544.
• Bobak, Martin. "Outdoor air pollution, low birth weight, and prematurity." Environmental health perspectives 108, no. 2 (2000): 173.
• Curtis, Luke, William Rea, Patricia Smith-Willis, Ervin Fenyves, and Yaqin Pan. "Adverse health effects of outdoor air pollutants." Environment International 32, no. 6 (2006): 815-830. - Abstract:
  
  Much research on the health effects of outdoor air pollution has been published in the last decade. The goal of this review is to concisely summarize a wide range of the recent research on health effects of many types of outdoor air pollution.
  
  A review of the health effects of major outdoor air pollutants including particulates, carbon monoxide, sulfur and nitrogen oxides, acid gases, metals, volatile organics, solvents, pesticides, radiation and bioaerosols is presented.
  
  Numerous studies have linked atmospheric pollutants to many types of health problems of many body systems including the respiratory, cardiovascular, immunological, hematological, neurological and reproductive/ developmental systems. Some studies have found increases in respiratory and cardiovascular problems at outdoor pollutant levels well below standards set by such agencies as the US EPA and WHO.
  
  Air pollution is associated with large increases in medical expenses, morbidity and is estimated to cause about 800,000 annual premature deaths worldwide [Cohen, A.J., Ross Alexander, H., Ostro, B., Pandey, K.D., Kryzanowski, M., Kunzail, N., et al., 2005.
  
  The global burden of disease due to outdoor air pollution. J Toxicol Environ Health A. 68: 1–7.]. Further research on the health effects of air pollution and air pollutant abatement methods should be very helpful to physicians, public health officials, industrialists, politicians and the general public.
• Lee, S. C., and M. Chang. "Indoor and outdoor air quality investigation at schools in Hong Kong." Chemosphere 41, no. 1 (2000): 109-113.
• Maheswaran, Ravi, Robert P. Haining, Paul Brindley, Jane Law, Tim Pearson, Peter R. Fryers, Stephen Wise, and Michael J. Campbell. "Outdoor Air Pollution and Stroke in Sheffield, United Kingdom A Small-Area Level Geographical Study." Stroke 36, no. 2 (2005): 239-243.
• Menzies, Richard, Robyn Tamblyn, Jean-Pierre Farant, James Hanley, Fatima Nunes, and Robert Tamblyn. "The effect of varying levels of outdoor-air supply on the symptoms of sick building syndrome." New England Journal of Medicine 328, no. 12 (1993): 821-827.
• Naeher, L. P., B. P. Leaderer, and K. R. Smith. "Particulate matter and carbon monoxide in highland Guatemala: indoor and outdoor levels from traditional and improved wood stoves and gas stoves." Indoor air 10, no. 3 (2000): 200-205.
• Ott, Wayne R., and John W. Roberts. "Everyday exposure to toxic pollutants." Scientific American 278, no. 2 (1998): 72-7.
• REFERENCES at the end of this document contain a more-extensive citation list addressing cargon dioxide and other gases
• Thompson, C. Ray, Earl G. Hensel, and Gerrit Kats. "Outdoor-indoor levels of six air pollutants." Journal of the Air Pollution Control Association 23, no. 10 (1973): 881-886.

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

 

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)

Question: is a level of CO₂ at 50 dangerous?

(Mar 15, 2013) France's said:

My brother has co2 level at 50, is this dangerous?

Reply:

France's, I'm sorry but I cannot form an confident opinion from your question as I have no idea what measurement was made, where, nor if we're talking about carbon dioxide level in air, in the bloodstream, or elsewhere

According to Medline, "In the body, most of the CO2 is in the form of a substance called bicarbonate (HCO_3,). Therefore, the CO₂ blood test is really a measure of your blood bicarbonate level."

If that is the measurement you mean, Medline explains that

"The normal range is 23-29 mEq/L (milliequivalent per liter)."

Your brother should ask his doctor for her opinion about the meaning of his tests.

Question: what kind of test is done for septic odors?

(Dec 19, 2012) test said:

What type of text might you recommend to be done in a place that often has septic odors? I fear that even when the odor is not there that the contaminants are left behind.

Reply:

Test,

While sewer gases or septic system odors contain a complex of gases typically people test for methane in air, and where there has been a sewage spill, a test of surfaces is performed for bacteria such as eColi associated with sewage.

Sewer gas is not itself a Carbon dioxide issue (the subject of this article where you posted the question) and is discussed separately at a couple of articles you'll want to see:

TEST FOR INDOOR SEWER GAS

SEWAGE CONTAMINATION in BUILDINGS

SEWER GAS ODORS - home

...

Continue reading  at CO₂ HEALTH EFFECTS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

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• AIR QUALITY on COMMERCIAL AIRCRAFT
• CARBON DIOXIDE - CO₂
  • CO₂ EXPOSURE LIMITS
  • CO₂ HEALTH EFFECTS
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  • TYPICAL CO₂ LEVELS
• CARBON MONOXIDE - CO - a different gas
• CONCENTRATIONS of GASES in AIR
• FRESH AIR VENTILATION RATES & STANDARDS
• GAS DETECTION INSTRUMENTS
• GAS EXPOSURE EFFECTS, TOXIC
• INDOOR AIR QUALITY IMPROVEMENT GUIDE

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Citations & References

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