A Procedural Checklist for Odor Source Diagnosis InspectAPedia® -
This procedural checklist helps diagnose and track down the source of building odors
Does your home have "BO" - building odor that is hard to track down? Here we suggest step by step procedures to help find the source of a building odor complaint.
How to eliminate sewer gas smells in basements, bathrooms, kitchens
How to remove septic smells or other odors of any kind from buildings
Links to articles on diagnosing and curing smells in buildings
Questions & answers on procedures used to identify the source of smells or odors in buildings - an odor source checklist
Building odor & smell diagnosis & cure procedure: This article provides a methodology useful for tracking down the sources of odors in buildings. When you can't seem to find the source of an annoying building smell, we suggest using these investigation methods that include noting the time, weather, area, operation of equipment and similar conditions that will help track a building odor problem to its source.
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How to find the cause of odors, odor sources, and how to find and cure the source of smells in building air, water, heating and cooling systems, or other sources.
Procedure Checklist for Diagnosing the Source of Odors or Smells in Buildings
We offer below a list of smell and odor diagnosis clues that any home owner, home inspector, or other investigator can follow in seeking to pinpoint the source of an annoying or obnoxious odor in buildings. Readers are asked to contact us to suggest additions or corrections to this list.
Often people's perception of odors varies with time and exposure or with a number of other site factors that make it hard to track down just where a smell is coming from. But if we think carefully about when, and under what conditions we notice odors, often that information is instrumental in tracking down an odor to its source and thus in helping us decide if an odor refers to a potentially dangerous or unhealthy condition.
This odor diagnostic checklist is in simple alphabetic order, not in order of probable cause, importance, or health risk, all of which can vary widely. A printer-friendly abbreviated version of this article is at Printer Friendly Odor Diagnosis Checklist, thanks to reader Kathleen Black
Odors & Specific Events as Sources: Gulf Oil Spill Odors: The New York Times reported in May 2010 that residents in New Orleans, Louisiana and as far as 100 miles inland from the coast have been observing a strange chemical odor that comes and goes, but also it is described as a "kind of sewage smell". The odor is speculated to be associated with the offshore Gulf oil spill. The Times article added that "More than 800 air samples are being tested by the state's scientists, the federal EPA, and private contractors hired by BP [British Petroleum] from the shoreland to ... population centers farther inland". To May 15 2010 these sources had declared the air "safe". Readers should also see Gulf Oil Spill & Air Quality.
Odor or Smell diagnosis log: using the possible odor sources or odor and smell causes in building air, water, or mechanical systems listed below, and elaborated in more detail in articles listed at ODORS, Smells, Gases in Buildings-Diagnosis & Cure, if you are having trouble diagnosing an odor problem in a building, try keeping a detailed record or log, by date and time, of your observations of the conditions and factors listed below.
Often data from just a few days or a week will provide a strong suggestion about where to look more closely to find and fix an odor problem in buildings, water, mechanical systems, or other building components. Your odor log can be just an informal set of notes, or you can use an organized spreadsheet or form.
Odors in boats, cars, campers, trucks: how to find and remove smells from vehicles, including moldy cars, dead animals, exhaust gas, burning smells, etc. See BOAT & CAR SMELLS & ODORS
Odors & Building Structure: does the odor relate to presence of a nearby air movement pathway such as a building stairwell, elevator shaft, or heating and cooling duct system?
Odors & Building height, use, occupancy: does the odor relate to the level in the building (convection currents are very powerful updrafts in high-rise buildings), to use of elevators, windows open or shut, stairwell or parking garage doors open or shut; condition of air shafts, cooking.
Odor Character: Describe the odor and its strength: chemical, flue gases, fuel gas, heating oil, sewer gas, rotten egg, mold, musty, plastic, food, cigarette, smoke, other. Also see Odors & Paints, below.
Odors from Chinese Drywall: CHINESE DRYWALL HAZARDS discussed indoor air quality concerns that may involve sulphur or "sewer gas" odors in buildings due to the use of corrosive sulphur and other outgassing from Chinese drywall used in some structures. These gases are also corrosive and can damage HVAC equipment as well as other building components including safety devices like smoke alarms and CO detectors.
Odors & Electrical Wiring: a smell of burning plastic may be associated with potentially dangerous overheating of electrical components, wire insulation, plastic receptacles or light switches. If you smell "burning plastic" or similar odors indoors or even outside of a building, a dangerous electrical failure could be present.
Following the explosion of an electrical transformer in a New York City sidewalk vault, the The New York Times reported that an employee of a nearby store and others in the area had observed an increasing "smoky odor that was growing stronger ... it smelled like burning plastic." Inside residential buildings, aluminum electrical wiring can overheat sufficiently to start a building fire without tripping a circuit breaker, or any electrical wiring can overheat if the circuit is overloaded, improperly used, or damaged. The risk is still greater if the circuit breaker such as FPE Stab-Lok or an improperly installed fuse have made circuit protection unreliable.
Turn off any suspicious or malfunctioning electrical circuits immediately, install smoke detectors, call your fire department, and hire an electrician familiar with aluminum wiring. See ALUMINUM WIRING HAZARDS,
Odors & Fans: while exhaust fans are often used to move odors out of a building, a little thinking and investigating may be in order: does the exhaust fan or whole house fan or attic roof vent fan cause odors, dust, or even mold to move upwards through the building? (Be careful that your whole house fan or other exhaust fans do not overpower and cause improper operation of your radon mitigation system if you have one installed).
Odors & Fireplaces: Type of fireplaces (gas, wood, coal), fire place door (glass vs screen), damper open/shut, in use, frequency of use.
Odors & Glues or Adhesives: many adhesives use a solvent that can produce very strong odors, espeically when the adhesive is recently applied. We suspect that adhesives used over wide areas are more likely to be noticeable in buildings, such as carpet or flooring adhesives. Also see GLUES ADHESIVES, EXTERIOR CONSTRUCTION.
Odors & Heating Equipment or other Appliances: does the odor appear only when certain appliances are running: cook stove, air conditioner, heater, aquarium pump, fans, clothes dryers, clothes washers, dishwashers, or electrical devices such as TV's?
Heating Oil fired equipment: If the odor appears to be related to oil burning appliances such as an oil fired furnace, boiler, or water heater, see OIL HEAT ODORS. If the odor appears due to a leaky oil tank or a heating oil spill, see OIL TANK LEAK ODORS.
LP or Natural Gas fired equipment: If the odor appears related to gas burning heating appliances, see chimney backdrafting, leaks, and odors from flues. Separately we discuss CARBON MONOXIDE hazards in buildings. Readers concerned with LP gas or natural gas combustion flue gas products and hazards should also see Natural Gas Combustion Products and also LP & Natural Gas Safety Hazards.
Odor history: when was the odor first noticed? What date? For how long has it been observed? Who first observed it? Does the first occurrence of a smell relate to an event, change, or modification in the building? If so, what exactly? Examples of events to which odors might be traced include:
Building occupancy: an event that involved an unusual number of occupants
Change, service, or replacement of HVAC equipment, change to duct work, filters
Events, such as a fire or flood, building cleaning, mold remediation, painting, use of deodorizers, pesticides, paints, coatings, insulating products
Modifications: additions, construction, window replacements, installation of insulation or change in building ventilation system or plumbing system or fixtures
Pets added to the building (see Odors & Pets below)
Purchases: of new furnishings, carpeting, draperies, blinds
Use of equipment such as an ozone generator following mold "cleanup" - see OZONE for MOLD OR ODORS
Weather, heavy snowstorms, other weather related events, possibly recurrent or cyclical. Also see Odors & time of occurrence, below.
Odors & indirect odor sources: a smell or odor that is perceived to be in a particular building area, in water, or even in individual items in a building may actually originate indirectly in another source. The New York Times reported an example of indirect odor causation in describing a Johnson & Johnson product recall of "several hundred batches of popular over-the-counter medicines, including Benadryl, Motrin, Rolaids, Simply Sleep, St. Joseph Aspirin and Tylenol".
The Times reported a statement by Johnson & Johnson subsidiary McNeil Consumer Healthcare that "... the breakdown of a chemical used to treat wood pallets that transport and store product packaging was the source of the moldy smell in some products."
OPINION: a diagnostic clue that the company might have used in tracking down this odor source would have been the appearance of a similar odor across multiple products whose contents are produced at different times, possibly on different fabrication lines, even possibly in different locations. What did these products share in common: perhaps the production of their containers.
An additional example of indirect sources of building smells is the ability of heating and cooling ducts to pick up odors from one location and transport them to another in the building, through the ductwork. See DUCT & AIR HANDLER ODORS.
Odors from building insulation: Insulation Odors: may be caused by contamination of the insulation by rodents or other animals (urine, feces, nesting materials), or mold (INSULATION MOLD). Some cellulose insulation may emit an odd odor if the cellulose manufacturer used an ammonium sulfate/borate mix. Details are at Cellulose Insulation Odors, Smells.
Odor location: does the odor appear throughout a building or only on certain floors, in certain rooms, or at certain walls?
What is different about the room where an odor appears:
What side of the building is the room on? What conditions are different there such as sun exposure, wind exposure, nearby trees, prevalent wind direction, outdoor possible odor sources?
What side of the room, what wall, has the strongest odor: is it an exterior or interior wall?
What materials are unique to the odor-source room, such as carpets, carpet padding, drapes, window shades, kind and type and age of windows, screens, heat, air conditioning, pet occupancy, people occupancy, laundry storage, proximity to baths, kitchens, laundry, openings between floors?
What is different about the floor or level in a building where odors occur? Proximity to basements, attics, leaks, rodents, pests, animals, heating equipment, pesticide treatments
See SMELL PATCH TEST to Track Down Odors This article describes a procedure that assists in pinpointing odor sources to a particular surface or piece of furniture or carpeting, using aluminum foil, paper towels, and simple masking tape.
Does the odor appear related to specific equipment such as heating or cooling system ductwork or air handlers? Does it occur only when certain equipment is operating?
Odors & Medical Conditions: consult with your physician to rule out illness, neurological disorder, or to ask about possible relationship between the odor complaint and medical condition or individual sensitivity. For example, pregnant women often have an increased sensitivity to odors. Some tumors or other illnesses are associated with changes in perception of odors.
Odors & Mold: moldy smells or odors present? visible mold in the building, history of building leaks? Mold odors are generally MVOCs - these gases are produced inconsistently, not by all molds, and not under all conditions; MVOC production may vary by indoor conditions such as temperature, humidity, light, darkness, even season or mechanical disturbance of moldy materials. SeeMOLD ODORS, Musty Smells in Buildings
Odors & neighbors: does the odor correlate with activities by building occupants or building neighbors? What about trash burning, level of septic system usage, use of woodstoves, coal stoves, home improvements, building projects, cooking, wine making.
Odors & occupants: does the odor occur when the building is occupied by large number of people, visitors, or specific individuals who may have brought something new into the building?
Odors & paints: paints, both exterior and interior are odor sources. Paint odors are strongest when the paint is being applied and during the paint drying process. But some high VOC paints may continue to outgas VOCs at low levels for years after initial application. Newer low-VOC interior paints and no-VOC interior paints were described in a New York Times article (Feb. 2010) in an application, odor, and durability test. After a manufacturer-recommended 6-week drying time, the low-VOC and zero-VOC paints were considered equivalent to higher VOC coatings in quality, and were described as low in odors during application when none of the paints was odor free, and odors "disappeared in an hour or so." Low-VOC and zero-VOC paints tested were described as temporarily producing odors such as wet cement, mild-ammonia (common), fruit, and sour smell. Also see Volatile Organic Compounds VOCs.
Odor perceivers: who notices the smells? Is the odor perceived only by certain occupants? Is the odor more noticeable to building occupants or to occasional visitors. People's sensitivity to many odors tends to diminish over longer exposure times as the odor-sensing neurons and brain response become desensitized.
Such individuals may notice an odor only upon entry to a building and not after being indoors for a time; people can also become desensitized to an odor such that even after leaving and returning to the building they do not notice the odor as much as is noticed by visitors. This seems especially true with animal and pet odors for people who live with pets.
Odors & Pets or other Animals in Buildings: what is the history of animals and pets occupying the building? What about prior owners and their pets. What about animal pests such as rodents: mice, squirrels, raccoons, insects, who may be responsible for smelly insulation, animal urine or fecal waste on building surfaces, dead animals in walls or ceilings. See Pet Odor Removal and see Building Inspection & Test Procedures for Pet Allergens.
Odors & Plumbing: does the odor presence relate to the use or dis-use of plumbing fixtures in the building? Does heavy usage bring out the odor problem? Problems with the building drain-waste-vent piping, leaks, and even loose toilets are common sources of sewer gases, septic odors, and even "rotten egg" odors in buildings.
Does the odor problem seem worse when the building has been unoccupied for some time? See SEWER GAS ODORS and SEWER GAS ODORS in COLD WEATHER for drain and septic system related odor diagnosis. See ODORS IN WATER for smells in drinking water or showers.
Does the odor problem appear only at a specific fixture such as a toilet? Check for a bad toilet wax ring seal. See Leaky Toilet Seals - Odors.
Odor strength: is the odor perceived as strong or mild? Does the level of smell vary? Under what conditions?
Odors & time of occurrence: does the odor appear all of the time or only at certain times. For odors that come and go, does the time of the odor correlate with:
Activities:Cooking activities may be an odor source
Time of day, sunlight, operation of heating or cooling equipment
Time of year, season, foliage, outdoor or indoor activities including activities of neighbors or industrial facilities that can produce odors, chemicals, gases, that move towards the subject property
Heating or cooling season: does the odor appear when the heating system comes on? Check immediately to assure that there are no carbon monoxide hazards or flue gas hazards. See CARBON MONOXIDE - CO
Odors in high-rise buildings: use of elevators, use of stairwells, doorways left open or shut during different periods
Use of equipment: operation of a vehicle in an attached garage, use of an ozone generator, electric motors that may be overheating
Odors & local temperature or other weather conditions: does the odor appear or disappear in relation to changes in building temperature?
Sunlight striking plastic window screens may make a distinctive odor only on the sunlit side of the building
Plumbing system drains or vent systems may release odors when a private septic system is under heavy use or in certain weather conditions - see SEWER GAS ODORS in COLD WEATHER;
Flooding conditions:
Also, if odors appear at drains or fixctures only in times of area flooding, odors at a basement floor drain (for example) may be due to backing up sewer or septic drain lines.
Odors & weather conditions: does the odor correlate with weather conditions such as humidity, temperature, rain, snow, wind? Does the odor or smell correlate with heavy snow-cover?
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"Odd Smells in New Orleans, Thoughts of the Gulf", Susan Saulny, The New York Times, 15 May 2010 p. A12.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
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
Allergies, Allergens, Allergy Testing in Buildings - References & Products
Allergen Tests in Buildings advice about how to test, what to look for, in evaluating the level of dog, cat, or other animal allergens in a building
"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
Animal Allergens: Dog, Cat, and Other Animal Dander - Cleanup & Prevention Information for Asthmatics and regarding Indoor Air Quality.
Recognizing Allergens: What various indoor allergens look like - identification photos to help identify pollen, dust mites, animal dander, toxic or allergenic mold - Common Mold and other Allergens, Irritants, Remedies & Advice
Rodent control issues, including dander, fecal, and urine contamination of Buildings and Building insulation are discussed at our
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