It's often difficult to find the cause of a building odor because neither the odor nor the airflow that carry the odor away from the source is visible.
What are some sources of building odors?
Bathrooms
In one building, people complained about not-so-fragrant odors in a work area near a bathroom. The area contained open work cubicles. The bathroom had a supply and an exhaust for the conditioned (heated or cooled) air. More air was being supplied than exhausted, so the air pressure in the room was higher than the air pressure right outside the room. Air flows from a higher pressure to a lower pressure, just as water falls from a higher level to a lower level. When someone used the bathroom, the odor was blown out through a large gap between the door and the threshold.
The cure for the problem was simple: Just reduce the airflow from the supply, so that the air pressure in the bathroom was less than the air pressure in the work area.
In another house, the guest bathroom had a sour smell. The owner was embarrassed to have his guests use the bathroom because of the odor. The culprits were mold and bacteria growing in the sink overflow. The owner poured a dilute bleach solution (one part bleach to ten parts water) down the overflow and scrubbed it out with a small brush, and the problem was solved.
Building Materials
Some fiberglass/plastic insect screens emit an unpleasant odor when heated by the sun. Some nylon bases of light fixtures can degrade, making the room smell like a dead fish. This odor is due to the chemical hexamethylenediamine, used to make nylon and closely related to cadaverine and putricine, chemicals that cause bad fish odor.
In a newly renovated space, paints, varnishes and other finishes as well as adhesives and carpeting can off-gas chemicals. In one new house, just built by a couple as their dream retirement home, the wife experienced headaches whenever she was in the house and had to move to an apartment. The first floor had an omnipresent chemical smell, strongest at the interior and exterior corners of the walls and at intervals of 16 inches on vertical "strips" on the walls from floor to ceiling.
When the house was being constructed, the drywall installers must have used joint compound to which they had added an odorous fungicide. This chemical was off-gassing, creating the unpleasant odor that was making the woman sick. There was no easy fix to this problem, unfortunately, short of replacing or covering all the drywall.
If you are living or working in a space that is about to undergo renovation, ask that low-VOC (volatile organic compound) products be used. Newly constructed or renovated spaces should be aired out before being reoccupied.
Doors made from pressed wood, kitchen cabinets made of medium-density fiberboard (MDF), and I-joists that contain oriented strandboard (OSB) can off-gas formaldehyde, which is irritating to some people. If the smell of formaldehyde bothers you or anyone in your household, avoid composites like OSB and MDF in building materials, as well as in furniture.
Furnishings
Some rugs have a thin, non-slip rubber backing that emits an odor reminiscent of a new automobile tire. Antique or used furniture may have musty-smelling, ancient surface mold growth if the furniture was ever stored in a damp basement or garage. Mold growth remains allergenic for years, even if dead. "Allergic responses can come from exposure to dead as well as living spores," affirms the New York State Department of Health.
Crawl Spaces and Basements
A moldy crawl space or basement can make the first floor or even the whole house smell musty.
Plumbing Sources
Sewer gas can escape around a loose toilet seal, or from a dried-out trap or a concealed screw hole in a pipe. Natural gas can leak out of inadequately tightened fittings or even pinholes in pipes.
Human Beings
People who wear fragrances or colognes, or who use fragranced laundry or body products carry these odors with them into buildings. Cleaning products that people use also off-gas chemicals into an interior space. Fragrances may smell pleasant, but these chemicals can be irritating to some people.
Pests
Mice impart unpleasant odors, especially if they die inside a wall or ceiling cavity. Other small pests that can invade houses, like chipmunks and shrews, are also smelly.
Why Are Some Building Odors Intermittent?
The strength of some building odors ebbs and flows, depending on human activity. Other building odors fluctuate depending on wind conditions at the exterior of the building. For example, if there's a smelly rodent nest in an external wall cavity, the smell will flow to the interior if wind is blowing against that wall at the exterior. This causes the air pressure in the wall cavity to be greater than the air pressure in the interior. The intensity of some odors can also depend on temperature and humidity. Off-gassing can increase as the temperature rises, and mold activity increases as the relative humidity rises.
Do Some People Have a Better Sense of Smell Than Other People?
To risk being politically incorrect, I've often found in my professional life that women generally have a better sense of smell than men do.
One study agrees with me. "The ability of women to show dramatic increases in olfactory sensitivity following repeated test exposures can explain many real-world phenomena in which females appear to be more sensitive and reactive than males ... in the presence of low-level odors."
If you are a man living in a house with a woman, and she detects an unpleasant odor that you can't smell, give her the benefit of the doubt!
Keep a Journal
Take notes as to when a building odor occurs. Does it occur during certain times of day? During certain weather or wind conditions? During certain seasons? During certain temperatures? Does the space contain new furniture or rugs? Ask if anyone else in the building detects the odor, and if so, when. Information like this can help you identify the odor source.
Identify the Odor Source
Close doors to isolate air flows, to see if the smell seems stronger in one room or area than another. Then in a room where the smell seems stronger, try the paper-towel test. Fold a piece of odorless paper towel in half, and then place it over an area you think may be emitting the odor. Cover the paper towel with a flat piece of aluminum foil, and secure the edges of the foil with removable painter's tape. Leave the paper towel package in place for 24 to 48 hours, then remove the towel and wrap it inside the foil. Take the package outside, unwrap the paper towel from the foil, and cautiously sniff the towel. If the surface on which the paper towel was sitting is off-gassing, the towel will have acquired some of the odor.
In the end, you may have to hire an indoor air quality professional or mold inspector to help you find the odor source and give you recommendations on remediation.
Sources
- Diamond, Jeanmarie et al., "Gender-specific Olfactory Sensitization: Hormonal and Cognitive Influences," Oxford University Press: Oxford Journals, Life Sciences and Medicine, Chemical Senses, Vol 30, Issue Supp 1, pp i224-i225
- "Indoor Air Quality: Mold," Albany, NY: New York State Department of Health
Resources
- "Indoor Air Quality Facts No. 4 (Revised): Sick Building Syndrome," Washington, DC: The U.S. Environmental Protection Agency
- May, Connie L., "Cleaning and Indoor Air Quality," "Mice, Shrews and Indoor Air Quality," Suite 101
- May, Jeffrey C., "Indoor Chemical Exposures, Suite 101
- "An Office Building Occupant's Guide to Indoor Air Quality," Washington, DC: The U.S. Environmental Protection Agency
- "Workplace Safety and Health Tips: Indoor Environmental Quality," Atlanta, GA: Centers for Disease Control and Prevention
Disclaimer: The information contained in this article is for educational purposes only and should not be used for diagnosis or to guide treatment without the opinion of a health professional. Any reader who is worried about his or her health should contact a doctor for advice.
Connie May - Connie L. May is a Certified Indoor Air Quality Technician (CIAQT) based in New England. She and her husband Jeffrey C. May, a Certified ...
