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Toxic Gas Exposure Standards Summary for Common Indoor Gases MoldAPedia © Enter your search terms Submit search form   Search This Website - InspectAPedia.com

• Guide to toxicity levels and technical notes for exposure to various gases found in buildings
• Indoor air quality testing for toxic gases - level of toxicity of gases
• How to test for toxic gases indoors and what levels of each gas are acceptable

This document outlines gas toxicity levels for a range of indoor gases which may be produced by heating systems, septic or sewer systems, building product outgassing, mold and MVOCs, heating systems, sewer lines, fire damage, or contamination from nearby industrial, beauty parlor, dry cleaning, or other activities which often produce noxious or toxic odors and gases. Readers of this document should see TOXIC GAS EXPOSURE HAZARDS LIBRARY, Toxic Gas Testing, and also see HEAT EXCHANGER LEAKS and GAS MEASUREMENT TOOLS . © Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Indoor Gas Exposure Limits, Gas Testing Limitations & Definitions

General Information about Exposure, Standards, Definitions

Gas Exposure Standards (workplace-based)

The purpose of general indoor gas exposure inspection and testing is to perform a general screen for the presence of specific problematic substances in response to specific concerns raised regarding the target property. Individual complaints about indoor air quality or smells can occur at extremely-low levels of certain gases or particles, in fact at levels considerably below typical allowable industrial permitted exposure levels (PEL's). Therefore we may select tests which screen for levels of gases considerably below permitted limits for industrial workplace exposure.

Important Gas Testing Safety Warning: because even small changes at a building can make an enormous difference in the presence or absence of a dangerous gas, consumers and investigators must keep in mind that any gas detection test represents conditions only at the instant that the test was performed. Simply turning on a fan, closing a door, or turning on or off a piece of heating equipment can change from safe to very dangerous conditions in a building. For this reason, gas testing alone, without a careful building visual inspection and history-taking, is unreliable as a safety indicator, particularly when the test does not detect the presence of a gas being sought.

Important Gas Toxicity & Exposure Limit Note: in most cases the toxic gas exposure limits available are for workplace settings. Conditions in the home, including assumptions about the health, age, and level of physical activity of occupants in a non-industrial setting are likely to mean that industrial exposure standards, while useful, are not a completely satisfactory safety guideline for other settings.

Gas Tests: Gas exposure or gas leak test equipment is checked for proper operation and calibration before and after the investigation; gas detection tests are conducted under operating conditions meeting the manufacturer's requirements; these tests are applicable only to the place, time, and date of measurement; the tests are not technically exhaustive.

Several gas detection instruments & methods are used, depending on whether we are screening for presence/absence of combustible gases, checking general indoor air quality, or testing and making quantitative measurements of specific gases in an environment. Some instruments are particularly helpful in tracking odors or leaks to their source.

Draeger Sampling Pump: We use the Draeger accuro™ Pump and Draeger-Tubes for gaseous substance sampling for both detecting the presence/absence of specific gases and for quantitative measurements of gas levels.

The Sensidyne™ Gastec piston pump and Gastec™ tubes for test for presence/absence of and level of certain gaseous substances.

Both of these toxic gas testing pumps are factory calibrated at 100 cc, and are leak-tested before and after each investigation. The adsorption tubes used for substance screening/identification are factory-calibrated. Other tests for specific substances: over 200 tests for over 500 different gases are available by using specific detector tubes. I can provide these when there is risk of a specific substance in a building. Unless there is a reason given for a narrow specific gas test in a building such tests are not economical and are simply "shooting in the dark."

The TIF 8850 combustible gas detector is a broad-spectrum gas screening instrument which is also useful to track and pinpoint the source of odors or leaks.

A partial list of gases detected by the TIF 8850 and its detection limits includes: [Note: these are instrument detection limits, NOT gas exposure limits which we in fact do provide just below at Gas Exposure Limits.]

• Acetone gas exposure limit - 50ppm,
• Acetylene gas exposure limit - 50ppm,
• Alcohols gas exposure limit -
• Ammonia gas exposure limit - (R717) 20ppm,
• Benzenegas exposure limit - ,
• Iso-Butane (R600a) gas exposure limit - 500ppm,
• Chlorine gas exposure limit - 1ppm,
• Ethane (R170) gas exposure limit - 500ppm,
• Ethylene gas exposure limit - 500ppm,
• Gasoline gas exposure limit - 1ppm,
• Hydrogen gas exposure limit - 500ppm,
• Hydrogen Sulfide gas exposure limit - 5ppm,
• Lacquer Thinners gas exposure limit - ,
• Methane (Natural Gas) gas exposure limit - 500ppm - see SEPTIC METHANE GAS for a discussion of methane toxicity and explosion hazards
• Methyl Chloride gas exposure limit - 5ppm,
• Methanol gas exposure limit - 50ppm
• Methyl Ether gas exposure limit - 500ppm,
• N-Butane gas exposure limit - ,
• Naphtha gas exposure limit - ,
• Propane ("bottled gas" R290) gas exposure limit - 500ppm,
• Toluene gas exposure limit - ,
• Vinyl chloride gas exposure limit - 5ppm. MDL are generally 1-500 ppm.

The TIF 8800 device is essentially the same as the TIF8850 and uses a TIF 8801 sensing tip.

We provide detailed suggestions for using theTIF8800 combustible gas dector at Using the TIF 8800 Gas Detector and we discuss alternative gas measurement tools at GAS MEASUREMENT TOOLS

General exposure limits reference list for specific gases tested indoors

Some general notes for specific gases, their toxicity, exposure hazards, and exposure limits follow in an aphabetized list. Also see 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. And see the NIOSH Pocket Guide to Chemical Hazards (this document is available online). Other comments in this section are from "Health Hazards of some Gases" Jack E. Peterson, P.E., CIH, Ph.D., May, 1987.

Ammonia Gas Characteristics, Toxicity, Simple Ammonia Gas Exposure Measurements

Ammonia [14] : "The current gas exposure limit TLV for ammonia is 25 ppm with a short-term exposure limit of 35 ppm. Both were designed to be low enough to cause no irritation in unhardened people. The OSHA PEL for ammonia is 50 ppm, as is the NIOSH Recommended Standard." [15]

Ammonia exposure limits: NIOSH REL: gas exposure limit TWA 25 ppm (18 mg/m3) ST 35 ppm (27 mg/m3); OSHA PEL: TWA 50 ppm (35 mg/m3)

We provide more details about ammonia gas exposure hazards at Ammonia Gas

Arsine Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

 Arsine [16]: gas exposure limit "The effects of arsine are completely avoided if 8-hr exposures are kept at or below 200 ug/cu. m, (0.05 ppm), the TLV and PEL." (Op. cit.).

Arsine gas exposure limits: NIOSH REL: Ca C 0.002 mg/m3 [15-minute];OSHA PEL: TWA 0.05 ppm (0.2 mg/m3)

We provide more details about arsinegas exposure hazards at Arsine Gas

Benzene Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

Benzene [17] 0.5/a: gas exposure limit for this test we select a sampling tube which is not Benzene specific (Draeger Benzene 0.5/a) in order to also screen for other aromatic hydrocarbons including toluene, xylene (more likely to be in carpet out gassing than benzene) and ethel benzene.

Benzene gas exposure limits: NIOSH REL: Ca TWA 0.1 ppm ST 1 ppm; OSHA PEL: [1910.1028] TWA 1 ppm ST 5 ppm

Bromine Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

Bromine [18]: "Bromine causes eye irritation and lacrimation (tearing) in concentrations below 1 ppm but above the TLV (and PEL) of 0.1 ppm. Concentrations irritating to the eyes should not be tolerated for more than 15 minutes." (Op. cit.)

Bromine gas exposure limits: NIOSH REL: TWA 0.1 ppm (0.7 mg/m3) ST 0.3 ppm (2 mg/m3); OSHA PEL™: TWA 0.1 ppm (0.7 mg/m3)

We provide more details about exposure to bromine gas at Bromine Gas.

Carbon Monoxide Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

Carbon monoxide gas [19]:  in general, no carbon monoxide (CO) should be found indoors in living or working spaces when performing an instantaneous check. But CO monitors may be expected to sound an alarm when a time-weighted exposure level reaches 500 ppm, as that threshold is intended to protect lives while avoiding sounding false alarms that may occur, for example, when there is a brief, low-level CO release when a gas-fired appliance is first ignited. NIOSH recommends a conservative PEL of 35 ppm, referring to an exposure of 8 hours/day, 40 hours/week, for a working lifetime " a workplace exposure limit.

Carbon monoxide exposure limits: NIOSH REL: TWA 35 ppm (40 mg/m3) C 200 ppm (229 mg/m3); OSHA PEL™: TWA 50 ppm (55 mg/m3). Readers should also review our more detailed review of CO hazards at Toxicity of Carbon Monoxide Gas Exposure, Carbon Monoxide CO Poisoning Symptoms, Carbon Monoxide Exposure Limits, and Links to Toxic Gas Testing Procedures

We provide extensive information about CO exposure at CARBON MONOXIDE - CO, and we provide more detail about CO exposure limits at Carbon Monoxide Gas

Carbon Dioxide Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

Carbon Dioxide [20] gas exposure limit "The highest TLV (and PEL) assigned to any material is assigned to carbon dioxide, namely 5000 ppm (NIOSH has recommended a Standard of 1.0% or 10 000 ppm for a 10-hr work shift with a ceiling of 3.0% or 30 000 ppm for any 10-min period).  Furthermore, these concentrations are far more an expression of good practice than a line between "safe" and "dangerous." 

Actually, the concentration of carbon dioxide must be over about 2% (20 000 ppm) before most people are aware of its presence unless the odor of an associated material (auto exhaust or fermenting yeast, for instance) is present at lower concentrations.

Above 2%, carbon dioxide may cause a feeling of heaviness in the chest and/or more frequent and deeper respirations.  If exposure continues at that level for several hours, minimal "acidosis" (an acid condition of the blood) may occur but more frequently is absent." (Op. cit.)

Details about carbon dioxide gas toxicity or CO2 exposure hazards are provided in a separate article at Toxicity of Carbon Dioxide Gas Exposure, CO2 Poisoning Symptoms, Carbon Dioxide Exposure Limits, and Links to Toxic Gas Testing Procedures

More information about gas hazards, gas toxicity, or other environmental hazards is available from public and professional agencies and associations such as the American Industrial Hygiene Association (AIHA) www.aiha.org, OSHA www.osha.gov, and the Mine Safety & Health Administration www.msha.gov. Also see Industrial Hygiene News.

Carbon dioxide gas exposure limits: NIOSH REL: TWA 5000 ppm (9000 mg/m3) ST 30,000 ppm (54,000 mg/m3) OSHA PEL: TWA 5000 ppm (9000 mg/m3)

We provide extensive information about Carbon Dioxide gas exposure at CARBON DIOXIDE - CO₂ and still more details about exposure to carbon dioxide gas exposure limits at Carbon Dioxide Gas

Formaldehyde Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

Formaldehyde [21] gas exposure limits - As an additional example using Formaldehyde, in a screen I may test for very low levels in a building (.05 ppm), but the range of human response (also widely variable individually) may be summed as follows:

> 3.0 ppm = respiratory impairment and damage

> 1.0 ppm = possible nasopharyngeal cancer

> 0.5 ppm = irritation to eyes & mucous membranes

> .01 ppm = mild irritation or allergic sensitization in some people

Formaldehyde exposure limits: NIOSH REL: Ca TWA 0.016 ppm C 0.1 ppm [15-minute]; OSHA PEL: [1910.1048] TWA 0.75 ppm ST 2 ppm

Formic Acid Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

Formic acid [22] this gas screen addresses acid gases which can be expected to be produced by fire, heat, or oxidation (such as from ozone treatment) in commercial and residential properties. Formic acid is readily metabolized and eliminated by the body. Nonetheless, some chronic effects have been documented. Excessive inhalation is a respiratory tract irritant.

Repeated exposure to formic acid gases (at higher levels) can result in an allergic reaction. It is a suspected mutagen, may cause long-term liver and kidney damage.  More about formic acid and its exposure effects can be read at http://encyclopedia.lockergnome.com/s/b/Formic_acid and at Cornell University's MSDS files: http://msds.ehs.cornell.edu/msds/siri/files/ckb/ckbjy.html

Formic acid exposure limits: NIOSH REL: TWA 5 ppm (9 mg/m3); OSHA PEL: TWA 5 ppm (9 mg/m3)

Methane Gas Hazards, Methane Gas Toxicity vs. Methane Explosion & Asphyxiation Risks, How to Measure Methane Gas Levels

Methane Gas Hazards are primarily of explosion or asphyxiation

We commented at Septic System Safety that methane gas which maybe encountered in septic system is both explosive and an asphyxiant. A thoughtful reader, George Fielder, previously a salesperson for GfG Instrumentation, pointed out that these are the hazards. (We had inaccurately stated that methane gas was "toxic".)

In its pure form, methane gas is odorles and colorless. However where it occurs in or at buildings, methane may be mixed with other products that do provide an odor, such as in septic or sewer gases. The point is that one should not assume that there is no explosion or methane gas risk simply because no gas odor is noticed in a building.

Methane Gas Exposure Limits

The ACGIH TLV (Threshold Limit Value) described for Methane Gas is: Simple Asphyxiant. It is not classifiable as to its carcingenicity.

Reference: OSHA describes methane, and its synonyms methyl hydride, marsh gas, and fire damp, at http://www.osha.gov/dts/chemicalsampling/data/CH_250700.html where OSHA assigns IMIS Code Number 1640 to Methane gas.

Measurement Instruments for Levels of Methane Gas

Mr. Fielder added that additionally, toxic and combustible gases like methane and H2S that would be found in a septic tank can be readily measured by a portable, handheld gas monitor that can be rented from almost any safety equipment supply company or trench equipment rental company like United Rentals. They are easy to use and understand direct reading instruments that if nothing else might satisfy the curiosity of the do-it-yourselfer who likes to stick his nose in it.

True the user will need to know and understand the measurement scale and exposure levels for the particular gases being measured but this also can be easily explained when renting said instrument and reviewing an MSDS sheet. Most portable handheld monitors on the market today are less complex than a volt-ohm meter and can readily be understood with a brief explanation.

Consult Your Local Safety Equipment Distributor

Readers who have the need to measure methane gas levels or who have questions about the hazards of entering confined spaces such as septic tanks should contact their local safety equipment distriutor for further advice. In addition, local fire & emergency service officials as well as gas distribution companies as well as some home inspectors or environmental testing firms may have expertise and gas testing or measurement equipment on hand.

More information about methane and other gas hazards, toxicity, or other environmental hazards is available from public and professional agencies and associations such as the American Industrial Hygiene Association (AIHA) www.aiha.org, OSHA www.osha.gov, and the Mine Safety & Health Administration www.msha.gov. Also see Industrial Hygiene News.

Stay out of Septic Tanks

We emphasize that in ordinary procedures used in the care, repair, or maintenance of septic systems, the safety warnings we've listed above should be followed with care, and in general, quantitative measurements of the level of methane or other gases are not needed during a septic system repair.

Readers who own, service, or live on a property which includes a private septic system should review SEPTIC METHANE GAS hazards and warnings, and should also review the extensive safety article at SEPTIC & CESSPOOL SAFETY.

Nitric Oxide Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

[23] "Nitric oxide is colorless and may have little or no odor. Nitrogen dioxide (and/or its dimer, nitrogen tetraoxide) is rust red and has a "typical" odor quite noticeable at 5 ppm and causes eye and nose irritation at 10 to 20 ppm. Currently (1987), the TLV is 3.0 ppm with an STEL of 5.0 ppm; the PEL is 5.0 ppm. NIOSH has recommended 1.0 ppm for a Standard." (Op. cit.)

See Nitrogen Oxides Gas for more exposure limit data.

Formic acid gas exposure limits: NIOSH REL: TWA 5 ppm (9 mg/m3); OSHA PEL: TWA 5 ppm (9 mg/m3)

Ozone Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

Ozone gas [24] "Ozone is a highly toxic gas but even highly toxic substances can be encountered safely. The main concern with this material is that concentrations to which people are exposed do not average more than 0.1 ppm over an 8-hr day, and do not exceed that value by more than a factor of 2 or 3 during the exposure." (Op. cit.)

Details about Ozone Gas hazards and the use of ozone generators or using ozone as a mold remedy are provided in depth at the following articles:

• The Use of Ozone Generators Indoors for Control of Odors and Mold Removal in Buildings: A Summary of Hazards and False Claims
• The Hazards of Ozone & Ozone Gas Generators Ozone Gas Exposure Hazards - A Summary of Ozone Hazards Indoors
• STANDARDS FOR OZONE EXPOSURE includes a discussion of the generation of excessive levels of indoor ozone where some models of air purifiers or air deodorizers are used
• How, When, and Why to Test for Ozone in Buildings
• Ozone Toxicity & Ozone Gas Exposure Hazards
• Our complete list of articles about ozone can be found at these links:

  OZONE as a "CURE" for TOXIC INDOOR MOLD
  WHAT IS OZONE- O₃
  OZONE AIR PURIFIER WARNINGS
  OZONE HAZARDS
  STANDARDS FOR OZONE EXPOSURE
  TESTING FOR OZONE
  OZONE TOXICITY
  OZONE ODORS, MOLD, REFS

Ozone gas exposure limits: NIOSH REL: C 0.1 ppm (0.2 mg/m3); OSHA PEL™: TWA 0.1 ppm (0.2 mg/m3)

Perchloroethylene (tetrachloroethylene) Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

Perchloroethylene (tetrachloroethylene): - drycleaning solvent: [OSHA comments from the January 19, 1989 Final Rule on Air Contaminants Project extracted from 54FR2332 et. seq. This rule was remanded by the U.S. Circuit Court of Appeals and the limits are not currently in force.] OSHA's former permissible exposure limits for perchloroethylene (tetrachloroethylene) were 100 ppm as an 8-hour TWA, 200 ppm as a STEL not to be exceeded for more than five minutes in any three-hour period, and 300 ppm as a ceiling.

On the basis of the chemical's narcotic effects in humans, the Agency proposed a revised PEL of 50 ppm TWA and a 15-minute STEL of 200 ppm for perchloroethylene; these are the limits recommended by the ACGIH (ACGIH 1986/Ex. 1-3, p. 464). NIOSH (Ex. 8-47, Table N6B) did not concur with the proposed limits and recommended that exposures be maintained at the lowest feasible limit and that this chemical be classified as a potential occupational carcinogen. OSHA has evaluated the health evidence for this substance and has determined that a further reduction in the PEL to 25 ppm as a TWA is warranted, and the Agency is establishing this limit in the final rule. Perchloroethylene is a clear, colorless, nonflammable liquid with an etheral odor.

Perchloroethylene is widely used as a solvent in the dry cleaning industry and in industrial degreasing operations. The narcotic effects associated with exposure to high levels of this chemical are well documented. A worker exposed to an estimated concentration of 1470 ppm perchloroethylene and Stoddard solvent for 3.5 hours lost consciousness (Stewart, Erley, Schaffer, and Gay 1961/Ex. 1-807).

The most comprehensive studies of the effects of prolonged exposure to perchloroethylene vapors on human volunteers were conducted by Stewart and colleagues (Stewart, Hake, LeBrun et al. 1974/Ex. 1-970; Stewart, Hake, Wu et al. 1977/Ex. 1-971); these investigators concluded that prolonged exposure to 200 ppm results in early signs of CNS depression, while no response was elicited in men or women exposed repeatedly to 100 ppm for seven hours/day, except that performance on the Flanagan coordination test was significantly decreased in some exposed subjects (Stewart, Hake, Wu et al. 1977/Ex. 1-971, p. 28).
-- Excerpt from PERCHLOROETHYLENE (TETRACHLOROETHYLENE) - OSHA -- DJ Friedman.
Also see TETRACHLOROETHYLENE TRICHLOROETHYLENE - OSHA.
Also see Tetrachloroethylene (Perchloroethylene) - U.S. EPA

Propylene Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

Propylene [25] "Propylene is a simple asphyxiant (that is, it acts by dilution of oxygen) and a rather poor anesthetic. Extremely high concentrations are required to produce any effect at all. No TLV or PEL has ever been established for this material and NIOSH has not recommended a Standard. Its lower explosive limit is 2% in air (the upper is 11.1%) and a reasonable value for a maximum permissible concentration (suggested by Gerarde in Patty's Industrial Hygiene and Toxicology, vol 2, p. 1204, Interscience, New York, 1963) is 1/5 of the LEL or 4000 ppm. (Op. cit.)

More details about exposure to propylene gas are at Propylene Gas.

Sulfur Dioxide Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

Sulfur Dioxide [26]"For sulfur dioxide, the TLV had been 5.0 ppm for many, many years, but in 1978 ACGIH announced its intention to reduce that TLV to 2.0 ppm; that was done in 1980. The reason for this was recent information indicating that chronic (long term, repeated) exposure to sulfur dioxide concentrations near 5.0 ppm was found to have some minimal effects on working populations.

Sulfur dioxide is an upper respiratory tract irritant and acute (single or short-term) exposures cause nothing but irritation of the nose and throat. Long term exposures to sulfur dioxide concentrations in excess of 2.0 ppm can be expected in some cases to cause minor lung changes." (Op. cit.)

Sulfur dioxide exposure limits: NIOSH REL: TWA 2 ppm (5 mg/m3) ST 5 ppm (13 mg/m3); OSHA PEL™: TWA 5 ppm (13 mg/m3)

More details about exposure to sulfur dioxide gas can be found at Sulfur Dioxide Gas.

Toluene gas [27] 5/b: gases which can be expected to be produced by fire, heat, or oxidation in commercial and residential properties. Toluol is a common contaminant produced by oxidized or burning carpets.

Toluene gas exposure limits: NIOSH REL: TWA 100 ppm (375 mg/m3) ST 150 ppm (560 mg/m3); OSHA PEL: TWA 200 ppm C 300 ppm 500 ppm (10-minute maximum peak)

Trichloroethylene Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

Trichloroethylene: NIOSH REL: 2 ppm 60minute CEILING during usage as an anesthetic agent and 25 ppm TWA during all other exposures; NIOSH considers trichloroethylene to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990].
Current OSHA PEL: 100 ppm TWA, 200 ppm CEILING,
300 ppm 5minute MAXIMUM PEAK IN ANY 2 HOURS. <.P>

"Trichloroethylene is believed to have been discovered in 1864 and was first commercially produced in Germany in the early 1900s. It has been commonly used for cleaning of metals and other parts since the introduction of the vapor degreasing process in the early 1930s and continues to be the standard by which other cleaning processes are compared. Today, its primary uses are as an intermediate in the production of hydrofluorocarbon refrigerants and as a cleaning agent.

"The health effects of trichloroethylene have been studied extensively. The most significant findings to come out of the many long-term animal studies of the chemical are that it has caused liver and lung tumors in mice.

The significance of these tumors to human health is unclear due to species differences in both trichloroethylene metabolism and reaction to the metabolites. This is supported by epidemiology studies of workers exposed to trichloroethylene that generally indicate no overall increase in cancer risk.

Although recent studies of a small population of exposed workers in Germany appear to show an increase in kidney cancer, these studies suffer from major design flaws and are inconsistent with the results of larger, better conducted studies.

The International Agency for Research on Cancer (IARC) currently considers trichloroethylene to be "probably carcinogenic to humans" (Group 2A), based on its conclusions that there is "limited" evidence of carcinogenicity in humans.

The epidemiological data base for trichloroethylene is considered by the American Conference of Governmental Industrial Hygienists (ACGIH), however, to support classification in Group A5 (Not Suspected as a Human Carcinogen) "since the substance has been demonstrated by well controlled epidemiological studies not to be associated with any increased risk of cancer in exposed humans."

The U.S. Environmental Protection Agency currently is conducting a reassessment of the carcinogenic potential of trichloroethylene.
-- quoted from White Paper on Trichloroethylene

See Trichloroethylene - IDLH Documentation U.S. CDC NIOSH
See OSHA comments from the January 19, 1989 Final Rule on Air Contaminants Project extracted from 54FR2332 et. seq. This rule was remanded by the U.S. Circuit Court of Appeals and the limits are not currently in force.
See OSHA's website of PELs - Permissible Exposure Limits

Vinyl Chloride Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

Vinyl chloride [28] gas exposure limits - may be a hazard in some building where vinyl products are present and exposed to heat, fire, or oxidation. I do not perform tests for this substance as it is beyond my experience.

Vinyl chloride: NIOSH REL: Ca; OSHA PEL: [1910.1017] TWA 1 ppm C 5 ppm [15-minute]

Volatile Organic Compounds (VOC's) and Mold-related VOC's, MVOC's:

VOC's gas exposure limits - are an outgas product of many substances such as paints, solvents, and in some cases, organic growths such as mold colonies. MVOC's refers to mold-generated volatile organic compounds.

There may be aesthetic or health-related complaints where VOC's or MVOC's are present. The absence of VOC's or MVOC's does not assure that problem molds are absent from a building, as the production of MVOC's by molds varies by genera/species and specific growth and environmental conditions such as changes in moisture or RH. Unless my report specifically states otherwise, my inspection and testing excluded these substances.

Notice: the author a consulting professional member of the American Industrial Hygiene Association  - AIHA but not a certified industrial hygienist, [29] and my investigation is not intended to certify any building as meeting any government or industry standards for workplace environments.

Xylene Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

Xylene gas gas exposure limits -

Here is some of the Xylene information on sources, environmental persistence, and toxicity from http://www.scorecard.org/chemical-profiles/html/xylenes.html .

Quoted material from the above web page is italicized below. I've edited for brevity and inserted a few comments. See the web link if you want to see all of the data in that report. The US EPA site info on this chemical is - http://www.epa.gov/oppt/library/pubs/archive/solvents/finlchr4.htm

FOOTNOTES on Gas Toxicity, Gas Exposure Level Testing, and Gas Exposure Standards

[1] Gas detection tubes are one of the classical measurement techniques of gas analysis (Ref. Drager Tubes - CMS Handbook).

The first detector tube was used in the U.S. in 1919 (for CO). Modern tubes offer quantitative results with a high degree of accuracy and selectivity. Basically, a "tube" is a glass tube which contains one or more chemical reagents which react with the measured substance by  changing color, hence the name "colorimetric gas detector tubes".

In most tubes, the length of stain, combined with the volume of pumped test-air and with other environmental variables such as RH and temperature provide a quantitative measure of the level of target substance present at the instant of sample collection. Other methods are available for long-term sampling where that approach is needed.

[2] These tests intended for use during and immediately after fires to protect firefighters and investigators.

[3]Draeger Simultaneous Sets I and II measure inorganic combustion gases.  Set III is for the measurement of organic vapors, most of which are not pertinent to this fire. The specific substances tested and the test results for each are listed in my Lab Report.

[4] Draeger Sampling Pump: I use the Draeger accuro 100 ml multi-stroke bellows Pump and Draeger-Tubes for gaseous substance sampling, or the Sensidyne Gastec 100 ml multi-stroke piston pump and Gastec tubes for certain gaseous substances. Both pumps are factory calibrated at 100 cc, and are leak-tested before and after each investigation. The adsorption tubes used for substance screening/identification are factory-calibrated.

[5] The 11^th substance (phosphine) is related to fertilizer fires and is unlikely at a residential property fire.

[6] IDLH "Immediately Dangerous to Life and Health; TLV" Threshold Limit Value.

[7] Benzene exposure limits: NIOSH REL: Ca TWA 0.1 ppm ST 1 ppm; OSHA PEL: [1910.1028] TWA 1 ppm ST 5 ppm

[8] Carbon dioxide exposure limits: NIOSH REL: TWA 5000 ppm (9000 mg/m³) ST 30,000 ppm (54,000 mg/m³) OSHA PEL: TWA 5000 ppm (9000 mg/m³)

[9] Carbon monoxide exposure limits: NIOSH REL: TWA 35 ppm (40 mg/m³) C 200 ppm (229 mg/m³); OSHA PEL: TWA 50 ppm (55 mg/m³)>

[10] Formaldehyde exposure limits: NIOSH REL: Ca TWA 0.016 ppm C 0.1 ppm [15-minute]; OSHA PEL: [1910.1048] TWA 0.75 ppm ST 2 ppm

[11] Formic acid exposure limits: NIOSH REL: TWA 5 ppm (9 mg/m³); OSHA PEL: TWA 5 ppm (9 mg/m³)

[12] Ozone exposure limits: NIOSH REL: C 0.1 ppm (0.2 mg/m³); OSHA PEL: TWA 0.1 ppm (0.2 mg/m³)

[13] Toluene exposure limits: NIOSH REL: TWA 100 ppm (375 mg/m³) ST 150 ppm (560 mg/m³); OSHA PEL: TWA 200 ppm C 300 ppm 500 ppm (10-minute maximum peak)

[14] Ammonia exposure limits: NIOSH REL: TWA 25 ppm (18 mg/m³) ST 35 ppm (27 mg/m³); OSHA PEL: TWA 50 ppm (35 mg/m³)

[15] "Health Hazards of some Gases" Jack E. Peterson, P.E., CIH, Ph.D., May, 1987. This data is from CompuServe's SAFETYNET forum 1989 and from the following articles:

[73766,1245] GASES.TOX 08-May-87 17240 ; 53

Title: Toxicity & hazards discussion of various gases

Keywords: Discussion of the toxicity and hazards of various gases, ammonia, arsine, bromine, carbon dioxide, carbon monoxide, ozone, nitric oxide, nitrogen dioxide, propylene, and sulfur dioxide.

[74756,40] CO 20-Dec-86 7050 40

Title   : Carbon Monoxide discussion by Jack Peterson

Keywords: CO CARBON MONOXIDE JACK PETERSON DISCUSSION THREAD

This is a discussion of carbon monoxide from lift trucks, by Jack Peterson, in response to a query on the message board.  Excellent nformation from one of the leading experts on the topic.

74756,40. [76701,115] COALAR.TXT 19-Aug-88 12814 17

Message thread on Carbon Monoxide Alarms

Keywords: CO CARBON MONOXIDE ALARM ALARMS MONITOR MONITORING TESTING

This file is a message board discussion on Carbon Monoxide alarms, featuring comments by one of the leading authorities on CO, Jack Peterson.

[16] Arsine exposure limits: NIOSH REL: Ca C 0.002 mg/m³ [15-minute];OSHA PEL: TWA 0.05 ppm (0.2 mg/m³)

[17] Benzene exposure limits: NIOSH REL: Ca TWA 0.1 ppm ST 1 ppm; OSHA PEL: [1910.1028] TWA 1 ppm ST 5 ppm

[18] Bromine exposure limits: NIOSH REL: TWA 0.1 ppm (0.7 mg/m³) ST 0.3 ppm (2 mg/m³); OSHA PEL: TWA 0.1 ppm (0.7 mg/m³)

[19] Carbon monoxide exposure limits: NIOSH REL: TWA 35 ppm (40 mg/m³) C 200 ppm (229 mg/m³); OSHA PEL: TWA 50 ppm (55 mg/m³)

[20] Benzene exposure limits: NIOSH REL: Ca TWA 0.1 ppm ST 1 ppm; OSHA PEL: [1910.1028] TWA 1 ppm ST 5 ppm

[21] Formaldehyde exposure limits: NIOSH REL: Ca TWA 0.016 ppm C 0.1 ppm [15-minute]; OSHA PEL: [1910.1048] TWA 0.75 ppm ST 2 ppm

[22] Formic acid exposure limits: NIOSH REL: TWA 5 ppm (9 mg/m³); OSHA PEL: TWA 5 ppm (9 mg/m³)

Methane gas exposure limits: Methane is discussed at Methane Hazards. Also see SEPTIC METHANE GAS for a discussion of methane toxicity and explosion

[23] Nitric oxide exposure limits: NIOSH REL: TWA 25 ppm (30 mg/m³); OSHA PEL: TWA 25 ppm (30 mg/m³)

[24] Ozone exposure limits: NIOSH REL: C 0.1 ppm (0.2 mg/m³); OSHA PEL: TWA 0.1 ppm (0.2 mg/m³)

[25] Propylene exposure limits: ?

[26] Sulfur dioxide exposure limits: NIOSH REL: TWA 2 ppm (5 mg/m³) ST 5 ppm (13 mg/m³); OSHA PEL: TWA 5 ppm (13 mg/m³)

[27] Toluene exposure limits: NIOSH REL: TWA 100 ppm (375 mg/m³) ST 150 ppm (560 mg/m³); OSHA PEL: TWA 200 ppm C 300 ppm 500 ppm (10-minute maximum peak)

[28] Vinyl chloride: NIOSH REL: Ca; OSHA PEL: [1910.1017] TWA 1 ppm C 5 ppm [15-minute]

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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
• 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
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• 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.
• 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.
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