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Gas testing pump (C) Daniel Friedman Toxic Gas Test Plan for Indoor Air Quality

  • GAS EXPOSURE SCREENING TEST - CONTENTS: Indoor air quality testing for toxic gases - level of toxicity of gases. Indoor Residential Toxic Gas Test Selection - Some Suggested Tests. Indoor Air Investigation Tests for substances in gas form. Associated Particulate Testing for Indoor Airborne Particle Levels & Particle Identification. How to test for toxic gases indoors and what levels of each gas are acceptable
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Toxic Gas Detection & Testing in buildings:

Toxic Gas Exposure Screenining Tests. This document outlines gas toxicity levels and gas testing procedures we use in field IAQ and environmental health investigations for a range of indoor gases which may be produced by building product outgassing, gas appliance leaks, plumbing and septic systems, mold and mold related volatile organic compounds MVOCs which people report as a "moldy smell".

Mmechanical systems such as heating system-produced carbon monoxide or flue gases, fire damage, or contamination from nearby industrial, beauty parlor, dry cleaning, or other activities which often produce noxious or toxic odors and gases are also tested.



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I.a. Indoor Residential Toxic Gas Test Selection - Some Suggested Tests

TIF 8800 combustible gas analyzer checking a furnace draft hood for spillage (C) Daniel FriedmanArticle Series Contents

Depending on the building history and occupant complaints, and with advice from industry experts, for screening purposes I select one or more gas detection tubes [1] prepared by Sensidyne™ or Drager™ or one or more multiple simultaneous gas detection sets which have been prepared by Draeger Safety specifically for fire scenes. [2]

Gas detector tubes, used with a special calibrated Sensidyn™ or Drager™ pump [3] provide specific, accurate tests for the presence of target substances at the moment of testing. A list of gas tests and test sets which I have frequently used in field investigations is listed below. 

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."

We also select among several methods for particle collection from appropriate complaint and non-complaint areas,  including air sampling, surface tape lifts, surface, carpet, or furniture vacuum.

Where bacteriological risks are considered, such as where there has been a history of sewage leaks, the inspector/test consultant may include floor surface sterile swabs from the complaint area and control non-complaint areas. Sample specifics and test results along with related remediation advice are detailed in our Field Investigation and Lab Test Report.

Odor Source Identification & Evaluation

Odor source detection procedures are also available at this website but they are not discussed in this article. Odor detection and removal are described in detail in our separate odor diagnosis document
at ODORS GASES SMELLS, DIAGNOSIS & CURE - home

Indoor Air Investigation Tests for substances in gas form

Draeger Simultaneous Test Sets I, II, and III:

Photograph of a Drager hand pump used to measure carbon dioxide levels in the environment.Building contents and the presence of hazardous substances are unknown at the start of fighting a fire. Studies have shown more than 450 substances are produced by a fire and possibly in other circumstances. Not all of these potentially toxic gases are present at every fire, but 11 inorganic gases are preset at most fires.

Ten of these gases and substances produced by burning common materials found in buildings are addressed by the Draeger Simultaneous Test Sets I and II. [5]

Set III screens for organic gases. The Draeger Simultaneous Test Sets screen for these specific substances in the immediate vicinity.

These sets also record a broader spectrum of substances, and the reaction systems used are deliberately non-specific in order to screen for likely and most-dangerous substances. The individual sampling tubes are marked to indicate the presence of the test substances at 1x and 5x the threshold limit value (TLV) [for maximum short term exposure in industry; there is not a similar residential standard].

a.   Drager Simultaneous Test Set I

i. Acid gases

ii. Hydrocyanic acid

iii. Carbon monoxide - see HEAT EXCHANGER LEAK TEST - separate article

iv. Alkaline gases

v. Nitrous fumes

b. Drager Simultaneous Test Set II

i. Sulphur dioxide

ii. Chlorine

iii. Hydrogen sulphide

iv. Carbon dioxide

v. Phosgene

c.   Drager Simultaneous Test Set III 

i. Keytones

ii. Aromatic hydrocarbons. Calibrated for toluene; benzene and xylene are indicated with similar sensitivity. The TLV4 for benzene is much lower than xylene but the acute risk involved in the two substances is alike. They share the same IDLH (2000 ppm).

iii. Alcohols. Such as methanol.

iv. Aliphatic hydrocarbons. E.g. n-hexane (extremely low TLV(TWA)=50ppm); the TLV for most of the other aliphates is assessed to 300 ppm. The acute risk involved in hexane, heptane, and octane is almost identical; all substances are assessed to similar IDLH values.

v. Chlorinated hydrocarbons. Imprinted tube values pertain to perchloroethylene. A general prediction can be made with respect to the sensitivity of other compounds with certain reservations. (Gasoline vapors will shorten the reading as long as their concentration is more than 100 ppm).

Benzene Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

Benzene [7] 0.5/a tests in the indoor environment

If there is a particular concern for Benzene we perform a test for this substance. We select a sampling tube which is not Benzene specific 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. Sensitivity 0.4 to 10 ppm (40 to 2 strokes). +/30%.  

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 Toxicity, Simple Gas Exposure Measurements

Carbon dioxide 100/a

We have this test available for field use as a general indicator of the level of fresh air and air exchange in a building, but not if the building is unoccupied or aggressively ventilated at the time of the inspection. If used, we perform this test using the Gastec pump and tubes produced by Sensidyne. We do not perform this test separately if we are using the Draeger Simultaneous Test set as it is already included in that set. Sensitivity 100 " 3000 ppm. 0.01 " 0.3 Vol.-%.

Details about carbon dioxide gas toxicity or CO2 exposure hazards are provided in a separate article
at CARBON DIOXIDE - CO2

Carbon Monoxide Gas Toxicity, Simple Gas Exposure Measurements

Carbon monoxide 2/a:

We may use this test as a safety screen in buildings where there is other evidence of a questionable gas-fired heater. If used, we perform this test using the Gastec pump and tubes produced by Sensidyne. We do not perform this test separately if we are using the Draeger Simultaneous Test set as it is already included in that set. Sensitivity 2-60 ppm. Alternate: Sensidyne™ Gastec™ 1/La 8-1000 ppm or 25-500 ppm.

Readers should also review our more detailed review of CO hazards
at CARBON MONOXIDE - CO

Also see HEAT EXCHANGER LEAK TEST

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.

Formaldehyde Gas Measurement Instruments, Tools & Test Kits

Details about and lists of sources for formaldehyde gas testing kits and equipment are
at FORMALDEHYDE GAS TEST KITS, METERS.

Details about formaldehyde gas exposure limits are found
at FORMALDEHYDE GAS EXPOSURE LIMITS - DETAILS

Details about formaldehyde hazards in buildings are found
at FORMALDEHYDE HAZARDS
 

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Formic acid Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

Formic acid1/a:

Because 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 it is an important screen for this topic. Sensitivity 1 to 15 ppm, 20 strokes.

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.

Ozone Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

Ozone:

At high or low levels (various test sensitivities are available) produced by popular indoor air "purifiers" and by commercial treatments for odors is a highly-reactive oxidizing gas which is dangerous to lung tissue itself. This gas may react with other building materials (as an oxidant) to produce secondary outgassing products which are also irritants or potentially unsafe. Ozone is highly reactive and volatile and may not be present in a building long after it was applied.

Choice of use or omit this screen depends on the circumstances of the particular investigation. As a regular practice I include this screen where ozone generating equipment is in use or where commercial equipment has been very recently in use. Sensidyne™ #182SB 2.5-100 ppm / #182U 0.025 " 3.0 ppm.

See Ozone Warnings at OZONE as a "CURE" for MOLD or ODORS

Details about Ozone Gas hazards and the use of ozone generators or using ozone as a mold remedy are provided in depth at the Ozone articles found at More Reading at the end of this article.

Toluene Gas Characteristics, Toxicity, Simple Gas Exposure Measurements

Toluene 5/b:

Because this is one of the most sensitive gas screens available to address gases which can be expected to be produced by fire, heat, or oxidation (such as from ozone treatment) in commercial and residential properties it is an important screen for this application.

Toluol is a common contaminant produced by oxidized or burning carpets. Sensitivity 5-300 ppm.

Gas Contaminant Measurement Procedures & Standards


II.c. Associated Particulate Testing for Indoor Airborne Particle Levels & Particle Identification

These tests are not normally part of indoor gas testing but may be added on request or based on site conditions.

Non-regulated particulates,

Non-regulated particles such as soot from fires, can include ultra-fine particles which can be breathed deeply into the gas-exchange area of the lung. We use both settled surface dust collection (adhesive tape) and surface or crevice-dust collection (particle collection by vacuum using Zefon-type "Air-o-cel(R)" or MCE-filter cassettes to obtain material for microscopic examination.

Quantitative testing using other methods that permit calculating of particle exposure by weight are available but we do not employ them [it is outside our area of expertise]. If such particles were collected and examined they are shown in the Lab Report.

Tests for Common indoor allergens & particles such as mold, pollen, cat or dog dander, fiberglass insulation fragments

Allergens and respiratory irritant particles such as animal dander, insect fragments, mite fecals, pollen, and mold spores may be sampled by a variety of means: slit-impaction air samplers, vacuum samples, surface tape, bulk, swab, and culture.

The specifics of what particle collection methods used, how and where particles were collected, the relationship of the collection areas to building occupants, complaints, or other important risk factors, and the building conditions that can dramatically affect the apparent particle level (such as turning on or off a fan during air sampling) should appear in the field investigation report and Lab Report.

See MOLD TESTING METHOD VALIDITY

and MOLD DETECTION & INSPECTION for examples of particle collection procedures.

 

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