Start with the most logical odor source. If odors do not seem to be coming from the immediate area, use chemical smoke to track air flows from adjacent areas from which the odors may be emanating. Also, remember that your nose quickly becomes used to most odors. "Reset" your nose often with clean air to more effectively track odors with your nose.

Biological Sources

• Is there an odor of mold or mildew in or near the complaint area?
• Is there mold or are any animals present?
• Is there standing water near the complaint area, or inside the air handler or ductwork?
• Is condensation often present on windows or cold surfaces?
• Is indoor relative humidity above 60%?

Excess moisture can cause mold, fungi, dust mites, and some bacteria to flourish.

Housekeeping Sources

• Do complaints occur during or just after housecleaning activities?
• Do housekeeping activities take place near the complainants?
• Are any new products in use?
• Are housekeeping products used according to directions?
• Are products stored in sealed containers or in vented rooms?

Outdoor Sources

• Are sources of odor or pollutants (e.g., vehicles, stored chemicals, trash) located near outdoor intakes?
• Are there sources nearby or upwind:
• combustion by-products from traffic, loading docks or flue exhausts?
• industrial, agricultural or lawn care activity?
• construction activity?
• Are pollen levels high?

Building Sources

• Has there been recent painting, roofing or other remodeling or construction?
• Were pesticides applied recently near the complaint area?
• Has new furniture, flooring or equipment been installed?
• Are solvents or other chemicals stored in poorly sealed containers?
• Is it overly dusty?

Due to wide differences in personal comfort levels and clothing influences, typically up to 2% of people in a space may be uncomfortable to some degree, so don't expect to obtain 100% satisfaction. Also, occupant discomfort may result from stressors such as glare, noise, ergonomics, or job or home stress.

Air Temperature and Humidity

• Is thermostat properly set?
• Is air flowing from the vent warm (for heating) or cool (for cooling)?
• Are drafts or direct sunlight causing discomfort?
• Is humidity too high or low (best if between 30-60% relative humidity)?
• Is condensation often present on windows or other cold surfaces?
• Is there an objectionable odor?

Outdoor Air Supply

• Is ventilation system turned on?
• Is vent(s) blocked?
• Is air flowing from vent(s)?
• Is outdoor intake blocked?
• Is air flowing into outdoor intake?
• Is duct blocked?
• Is outdoor air supply at least 15 ctm per person?
• Is CO2 in the area less than 1000 ppm?

If onset was sudden or severe, check for carbon monoxide poisoning (see Identifying an Emergency). Note if symptoms dissipate after leaving the building or room. These symptoms have many potential causes, so check for adequate ventilation or unusual pollutant sources in the building or room.

Biological Sources

• Is there an odor of mold or mildew in or near the complaint area?
• Is there mold or are any animals present?
• Is there standing water near the complaint area, or inside the air handler or ductwork?
• Is condensation often present on windows or cold surfaces?
• Is indoor relative humidity above 60%?

Excess moisture can cause mold, fungi, dust mites, and some bacteria to flourish.

Housekeeping Sources

• Do complaints occur during or just after housecleaning activities?
• Do housekeeping activities take place near the complainants?
• Are any new products in use?
• Are housekeeping products used according to directions?
• Are products stored in sealed containers or in vented rooms?

Outdoor Sources

• Are sources of odor or pollutants (e.g., vehicles, stored chemicals, trash) located near outdoor intakes?
• Are there sources nearby or upwind:
• combustion by-products from traffic, loading docks or flue exhausts?
• industrial, agricultural or lawn care activity?
• construction activity?
• Are pollen levels high?

Building Sources

• Has there been recent painting, roofing or other remodeling or construction?
• Were pesticides applied recently near the complaint area?
• Has new furniture, flooring or equipment been installed?
• Are solvents or other chemicals stored in poorly sealed containers?
• Is it overly dusty?

Air Temperature and Humidity

• Is thermostat properly set?
• Is air flowing from the vent warm (for heating) or cool (for cooling)?
• Are drafts or direct sunlight causing discomfort?
• Is humidity too high or low (best if between 30-60% relative humidity)?
• Is condensation often present on windows or other cold surfaces?
• Is there an objectionable odor?

Outdoor Air Supply

• Is ventilation system turned on?
• Is vent(s) blocked?
• Is air flowing from vent(s)?
• Is outdoor intake blocked?
• Is air flowing into outdoor intake?
• Is duct blocked?
• Is outdoor air supply at least 15 ctm per person?
• Is CO2 in the area less than 1000 ppm?

Air Handling Unit

• Is the system turned on?
• Is air flowing from vent(s)?*
• Is the fan operating?
• Is filter(s) clean and properly installed?
• Are dampers operating properly
• Is there moisture, debris or microbial growth in or near the unit?
• Is the drain pan clean and draining?
• Are the coils clean?
• Is combustion equipment properly vented, no flue leaks or backdrafting?

Local Exhaust

• Does exhaust turn on?
• Is the exhaust used when needed?
• Is air flowing out of the exhaust vent?*
• Is exhaust ductwork blocked?
• Is a sufficient amount of air being exhausted?**
• If everything works, but not enough air is being exhausted, can make up air easily enter the room (e.g., through spaces under doors)?

* Airflow
To detect airflow, use special chemical smoke or a piece of tissue. Release puffs of smoke near openings between the complaint area and adjacent areas (openings include cracks; ducting; wiring, and plumbing passageways; and leaky or open doors and windows). Release smoke near vents and grilles to determine airflow direction, if any. Do not breathe on or move quickly near puffs of smoke.

** Air Volume
Flowhoods are designed to measure airflow at grilles and diffusers. Pilot tubes are designed to Measure air velocity in ducts, which is then used to calculate airflow. While flowhoods are more expensive to purchase, they are quicker and easier to use, and can be used to measure airflow in ducts by summing the airflows from all vents connected to a given duct.

May be allergic, if only a small number are affected (check Biological Sources first); more likely to be irritation response if large number are affected (check Housekeeping, Outdoor or Building Sources first). Symptoms may dissipate when away from building. Check for strong pollutant sources in the area/room (e.g., paint, solvent, adhesive, aerosol products, cleaners, petroleum products, printing, cooking). Check for any new pollutant sources. Also see symptoms directly below this one on the main problem solving page.

Biological Sources

• Is there an odor of mold or mildew in or near the complaint area?
• Is there mold or are any animals present?
• Is there standing water near the complaint area, or inside the air handler or ductwork?
• Is condensation often present on windows or cold surfaces?
• Is indoor relative humidity above 60%?

Excess moisture can cause mold, fungi, dust mites, and some bacteria to flourish.

Housekeeping Sources

• Do complaints occur during or just after housecleaning activities?
• Do housekeeping activities take place near the complainants?
• Are any new products in use?
• Are housekeeping products used according to directions?
• Are products stored in sealed containers or in vented rooms?

Outdoor Sources

• Are sources of odor or pollutants (e.g., vehicles, stored chemicals, trash) located near outdoor intakes?
• Are there sources nearby or upwind:
• combustion by-products from traffic, loading docks or flue exhausts?
• industrial, agricultural or lawn care activity?
• construction activity?
• Are pollen levels high?

Building Sources

• Has there been recent painting, roofing or other remodeling or construction?
• Were pesticides applied recently near the complaint area?
• Has new furniture, flooring or equipment been installed?
• Are solvents or other chemicals stored in poorly sealed containers?
• Is it overly dusty?

Check for microbial contamination in the air handling unit and ductwork. A medical evaluation can help identify possible causes, such as Hypersensitivity pneumonitis or humidifier fever. Also see symptoms directly above this one on the main problem solving page.

Biological Sources

• Is there an odor of mold or mildew in or near the complaint area?
• Is there mold or are any animals present?
• Is there standing water near the complaint area, or inside the air handler or ductwork?
• Is condensation often present on windows or cold surfaces?
• Is indoor relative humidity above 60%?

Excess moisture can cause mold, fungi, dust mites, and some bacteria to flourish.

Building Sources

• Has there been recent painting, roofing or other remodeling or construction?
• Were pesticides applied recently near the complaint area?
• Has new furniture, flooring or equipment been installed?
• Are solvents or other chemicals stored in poorly sealed containers?
• Is it overly dusty?

Air Handling Unit

• Is the system turned on?
• Is air flowing from vent(s)?*
• Is the fan operating?
• Is filter(s) clean and properly installed?
• Are dampers operating properly
• Is there moisture, debris or microbial growth in or near the unit?
• Is the drain pan clean and draining?
• Are the coils clean?
• Is combustion equipment properly vented, no flue leaks or backdrafting?

* Airflow
To detect airflow, use special chemical smoke or a piece of tissue. Release puffs of smoke near openings between the complaint area and adjacent areas (openings include cracks; ducting; wiring, and plumbing passageways; and leaky or open doors and windows). Release smoke near vents and grilles to determine airflow direction, if any. Do not breathe on or move quickly near puffs of smoke.

May be Legionnaire's disease or histoplasmosis, related to bacteria or fungi found in the building or near outdoor air intakes. Contact your local or State Health Department for guidance.

Biological Sources

• Is there an odor of mold or mildew in or near the complaint area?
• Is there mold or are any animals present?
• Is there standing water near the complaint area, or inside the air handler or ductwork?
• Is condensation often present on windows or cold surfaces?
• Is indoor relative humidity above 60%?

Excess moisture can cause mold, fungi, dust mites, and some bacteria to flourish.

Air Handling Unit

• Is the system turned on?
• Is air flowing from vent(s)?*
• Is the fan operating?
• Is filter(s) clean and properly installed?
• Are dampers operating properly
• Is there moisture, debris or microbial growth in or near the unit?
• Is the drain pan clean and draining?
• Are the coils clean?
• Is combustion equipment properly vented, no flue leaks or backdrafting?

* Airflow
To detect airflow, use special chemical smoke or a piece of tissue. Release puffs of smoke near openings between the complaint area and adjacent areas (openings include cracks; ducting; wiring, and plumbing passageways; and leaky or open doors and windows). Release smoke near vents and grilles to determine airflow direction, if any. Do not breathe on or move quickly near puffs of smoke.