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 Responding to Risk of Odorless Gases & Chemicals in Buildings
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Odorless gas or chemical hazards in buildings: this article discusses what to do about indoor contaminants that might not smell or give any ready indication of their presence. This website series provides articles on to diagnose, test, identify, and cure or remove a wide range of obnoxious or even toxic
odors in building interiors, building mechanical systems, or in building water supply. We discuss odors from a variety of sources including
animals including pets, dogs, cats, or unwanted animals or dead animals, formaldehyde odors in buildings from building products or furnishings, plumbing drains, plastic or vinyl odors from building products, flue gases, oil tanks or oil spills, pesticides,
septic odors, sewer gases, and even abandoned chemicals at properties. Our page top photo shows outdoor evidence of a radon mitigation system at a building. Radon is an example of an odorless, colorless gas that at elevated levels can be a health hazard for building occupants.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
How to Think About Indoor Contaminants that Avoid Detection - Gases or Chemicals that do not Produce a Smell
Question About Indoor Chemical or Gas Hazards that Don't Smell
I am writing to ask you whether it is true that some chemicals are odorless. The reason for the question is that the smell seems to be dissipating. However, since we we do not know what the source of the smell was, we cannot know for sure whether the source causing the smell can still be harmful to our unborn baby.
-- Jacqueline Saenz, CA.
Answer:
OPINION: Some chemicals are odorless - for example see "Fish Tale" in the New York Times. The article discussed a type of food poisoning (not a building material or sewer gas issue) associated with unsafe seafood - ciguatera poisoning (eating fish contaminated with a toxin that grown on reef algae) stating "Unlike most other causes of food poisoning, this toxin is colorless and odorless and isn't destroyed by cooking."
RADON HAZARD TESTS & MITIGATION
: if your building is over radon-bearing soils and rock, this odorless, colorless gas could be a health hazard. Testing and remediation are well understood and not technically difficult.
Similarly, carbon monoxide (CO) gas, (see CARBON MONOXIDE - CO) can be found in buildings where there is a gas burning appliance or chimney defect, is odorless and colorless.
But neither radon nor CO is ever smelly. So if there was an indoor odor present that later dissipated, it was not likely to be one of those particular hazards.
Because your original question (not included above) concerned sewer gas, it would be methane, not CO gas would have been more likely to be detected in your building. Sewer gas, a complex of gases, is not normally odorless. But sewer gas odors can indeed "come and go" depending on several variables, as we discuss below.
Building Indoor Odors / Smells that Eventually Diminish or Stop Completely
The types of building materials that smell for a while but then stop on their own, with no discover, repair, or removal of the offending source, include:
- New building products - smells that dissipate and do not usually return, material, coatings, especially products that emit VOCs or other gases such as formaldehyde.
Examples of sources of indoor odors that typically diminish or stop entirely include some brands of carpeting, cabinets or shelving made from particle board, furniture (upholstered furniture using certain foam products and possibly even coverings such as a vinyl couch, glues used in applying tile or other ceiling or flooring products, some plywood products, rubber tub mats, sheet flooring (vinyl floors), paints, vinyl or rubber window curtains or shower curtains. We found a horrible building chemical smell traced to new 6-mil polyethylene plastic that had just been placed on the ground over a crawl space that extended below the structure. See
these examples:
Building Odors / Smells That May Come and Go
- Animal smells - odors from visiting animals may eventually dissipate after the pest or pet has been out of the building for weeks or months.
- Heating Equipment, Age, Types, furnaces, boilers, water heaters, if there is a chimney cap or other venting defect, may make odors intermittently in buildings - for example stopping seasonally when the heater is not used. See BACKDRAFTING HEATING EQUIPMENT.
- Sewer gases - odors from drains may come and go seasonally, or depending on fixture use. See SEWER GAS ODORS in COLD WEATHER.
- Changes in building conditions can make even a long-lasting odor "come and go", including
- Variations in building indoor temperature and humidity
- Variations in weather, building leaks and moisture levels from outside conditions that affect the indoors
- Changes in building air movement: fans on or off, doors open or shut, windows open or shut, elevators in use or not, stairwells open or closed, different HVAC equipment in or out of use (heating vs cooling), cars running in a garage with a garage door open or shut (watch out for fatal carbon monoxide poisoning)
So How Might we Suspect and Decide to Test for an Odorless Gas or Chemical in Our Apartment?
Luckily, in most cases in buildings and building materials, problem chemicals or gases are delivered in a soup of materials, not in a pure form, and even if the dangerous material is odorless, most often it is in a soup that has an odor. For example, see BOILER NOISE SMOKE ODORS.
For example, carbon monoxide may be odorless, but if it's being delivered by a chimney leak or a car exhaust, other ingredients in those gases are often noticeable.
Watch out: often does not mean always. If building occupants are asleep during a CO poisoning hazard they could be asphyxiated without ever waking up. That is why it is really smart to have both working smoke detectors and working carbon monoxide detectors in your home.
How can I Check for or Test for Odorless Indoor Toxic Contaminants and Chemicals
OPINION: It is not cost-reasonable to try to test for every possible contaminant in a building, chemical or gas: there are just too many possibilities, and there not any simple inexpensive broad-spectrum "catch all" test. See TOXIC GAS TEST PROCEDURES. Don't just make a "wild guess" and then just test for that contaminant - doing so may lead to a false sense of security while you may be ignoring a problem that was not detected because it was not looked-for.
Make a Quick Amateur Do-it-yourself Building Contaminant Risk Assessment
Therefore our approach is to decide when further investigation or action is needed (do we need to "hire an expert") based on an initial level of risk assessment:
- Are there building-related occupant complaints? This is a subjective measure but it can be helpful to know if people appear to react with IAQ or health or respiratory complaints when they enter or spend time in a specific building or building area.
- Is there visible evidence of something thought to be a concern, some building condition or building event that often leads to an indoor environment or air quality worry, such as evidence of leaks, mold remediation (was the cleanup performed correctly) or a radon mitigation system (is it working properly?)
- Is there history of leaks from any source that have wet building materials or cavities (possible hidden mold)
- A sewer backup (bacterial hazards) - see ODORS, SEPTIC or SEWER
- Unusual products, such as old chemical bottles
- Stains, spills
that might need explanation
- Is there historical evidence that suggests a problem is highly likely though hidden
- A history of building use and building occupants may disclose prior activities that produced or used unsafe products or chemicals (gases? probably dissipated)
- A client bought a strip mall; we saw an abandoned trailer on the property - it had been used to store pesticides - turned out not to be a problem, as nothing had leaked;
But later the client called to say that four owners back a tenant had done metal plating and there was heavy metal cadmium contamination in some of the soil - DEC wanted it cleaned up. No one dreamed this problem was lurking, but a more extensive historical research of building occupants and uses might have raised this question by identifying a metal plating operation years before.
- Is there visual evidence that suggests a problem by "indirect evidence"
- A client was buying a house; we saw evidence of a history of termite damage but no evidence of professional treatment (drill holes around the perimeter of the concrete floor slab that had been capped); we did
see irregular, angled drill holes in floor framing near termite damage (possible unprofessional pesticide application); there was no record of professional pest control treatment; we took a sliver of wood from a sill plate for mailing to a test lab.
The lab confirmed that a now-banned pesticide, chlordane, had been liberally applied to wood surfaces. Possibly improperly. At a minimum, precautions during renovations were in order.
If there is evidence of a specific concern, or type of concern, then further testing may be in order.
If there is evidence of building related complaints, a visual inspection by an expert, combined with history taking about the occupants and the building, and possibly specific targeted tests, may be in order. See Pesticide Exposure Hazards.
- Other examples of "indirect evidence" that can lead to important discoveries about conditions at a property are discussed at Developing Your X-Ray Vision
Other Building Hazards are Latent - Odorless, Colorless, Until an Event: Building Fire or Flood
Other indoor hazards are simply lurking, like a stair-fall: nothing happens until something else happens.
- VINYL CHLORIDE HEALTH INFO discusses possible health concerns from PVC, dioxin, or HCL outgassing that occurs in vinyl building products (siding, windows, trim) are consumed in a fire (and possibly at lower levels from heating such as by sunlight).
- Ozone Odors & Ozone "deodorizers" - sometimes misuse of this equipment actually creates a hazard indoors
- See INDOOR AIR HAZARDS TABLE for a comprehensive list of indoor IAQ concerns
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
- Thanks to reader Jacqueline Saenz for discussing concerns of both noticeable indoor odors and worry about remaining unsafe chemicals or products that do not smell. 4/12/2010
- "Fish Tale", Diagnosis: Lisa sanders, MD, New York Times Sunday Times Magazine 4/11/2010, reported on a case of of ciguatera poisoning following consumption of contaminated barracuda shark flesh while visiting the Bahamas. The case was diagnosed by Dr. Kurtland Ma.
- ASTM E2600 - 08 Standard Practice for Assessment of Vapor Intrusion into Structures on Property Involved in Real Estate Transactions is available from the ASTM at astm.org/Standards/E2600.htm .
"This practice is intended for use on a voluntary basis by parties who wish to conduct a VIA on a parcel of real estate, or more specifically conduct a screening evaluation to determine whether or not there is potential for a VIC, and if so, identify alternatives for further investigation."
The standard goes on to emphasize the uncertainty in testing any site for gases and vapor intrusion.
- Kansas State University, department of plant pathology, extension plant pathology web page on wheat rust fungus: see http://www.oznet.ksu.edu/path-ext/factSheets/Wheat/Wheat%20Leaf%20Rust.asp
- "A Brief Guide to Mold, Moisture, and Your Home",
U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
- US EPA - Mold Remediation in Schools and Commercial Building [ copy on file as /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
- US EPA - Una Breva Guia a Moho - Hongo [on file as /sickhouse/EPA_Moho_Guia_sp.pdf - - en Espanol
- "IgG Food Allergy Testing by ELISA/EIA, What do they really tell us?" Sheryl B. Miller, MT (ASCP), PhD, Clinical Laboratory Director, Bastyr University Natural Health Clinic - ELISA testing accuracy: Here is an example of Miller's critique of ELISA
http://www.betterhealthusa.com/public/282.cfm - Townsend Letter for Doctors and Patients
The critique included in that article raises compelling questions about IgG testing assays, which prompts our interest in actually screening for the presence of high levels of particles that could carry allergens - dog dander or cat dander in the case at hand.
http://www.tldp.com/issue/174/IgG%20Food%20Allergy.html contains similar criticism in another venue but interestingly by the same author, Sheryl Miller. Sheryl Miller, MT (ASCP), PhD, is an Immunologist and Associate Professor of Basic and Medical Sciences at Bastyr University in Bothell, Washington. She is also the Laboratory Director of the Bastyr Natural Health Clinic Laboratory.
- Allergens: Testing for the level of exposure to animal allergens is discussed at http://www.animalhealthchannel.com/animalallergy/diagnosis.shtml (lab animal exposure study is interesting because it involves a higher exposure level in some cases
- Allergens: WebMD discusses allergy tests for humans at webmd.com/allergies/allergy-tests
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
 The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.
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