Check for microbial contamination in the Air Handling Unit and ductwork. A medical evaluation can help identify possible causes, such as carbon monoxide poisoning, hypersensitivity pneumonitis or humidifier fever. Also see information under the symptoms: "Swelling, itching, or irritated eyes, nose or throat; congestion."

Air Handling Unit

• Is the system turned on?
• Is the airflow from vents sufficient?¹
• Are the fans turned on?
• Are the filters clean and properly installed?
• Are dampers operating correctly?
• Is there moisture, debris or mold in or near the unit?
• Are drain pans clean and sloped toward the drain?
• Do coils need to be cleaned?
• Is combustion equipment properly vented without flue leaks or backdrafting?

Biological Sources

Excess moisture can cause mold, dust mites and bacteria to flourish. Moist or wet materials should be dried within 24-48 hours to avoid mold growth or replaced if mold already exists.

• Do you see or smell mold?
• Are there signs of rodents or pests?
• Are there animals or pets in classrooms?
• Is condensation often present on windows or cold surfaces?
• Do you see wet or frequently damp areas?
• Is indoor relative humidity above 60 percent?

Building Sources

• Has there been recent
  • Painting
  • Roofing
  • Remodeling
  • or construction?
• Were there pesticides applied recently?
• Has new furniture, flooring or equipment been installed?
• Are solvents or other chemicals stored in poorly sealed containers?
• Are areas in the building overly dusty?
• Are combustion appliances used in rooms without adequate ventilation?

¹ 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
• Ducts
• 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 mold found in the building or near outdoor air intakes. Contact your local or state health department for guidance.

Air Handling Unit

• Is the system turned on?
• Is the airflow from vents sufficient?¹
• Are the fans turned on?
• Are the filters clean and properly installed?
• Are dampers operating correctly?
• Is there moisture, debris or mold in or near the unit?
• Are drain pans clean and sloped toward the drain?
• Do coils need to be cleaned?
• Is combustion equipment properly vented without flue leaks or backdrafting?

Biological Sources

Excess moisture can cause mold, dust mites and bacteria to flourish. Moist or wet materials should be dried within 24-48 hours to avoid mold growth or replaced if mold already exists.

• Do you see or smell mold?
• Are there signs of rodents or pests?
• Are there animals or pets in classrooms?
• Is condensation often present on windows or cold surfaces?
• Do you see wet or frequently damp areas?
• Is indoor relative humidity above 60 percent?

¹ 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
• Ducts
• 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.

If onset was sudden or severe, check for carbon monoxide poisoning (see the "What to do in an emergency" section at the top right of this page for more information). Note if symptoms dissipate after leaving the building or room. Since these symptoms have many potential causes, check for adequate ventilation or unusual pollutant sources in the building or room.

Air Handling Unit

• Is the system turned on?
• Is the airflow from vents sufficient?1
• Are the fans turned on?
• Are the filters clean and properly installed?
• Are dampers operating correctly?
• Is there moisture, debris or mold in or near the unit?
• Are drain pans clean and sloped toward the drain?
• Do coils need to be cleaned?
• Is combustion equipment properly vented without flue leaks or backdrafting?

Air Temperature and Humidity

• Is the thermostat set properly?
• Is air flowing from the vent too cool or too warm?
• Are drafts or direct sunlight causing discomfort?
• Is the humidity too high or low? (Recommended range is 30-60 percent relative humidity.)
• Does condensation frequently form on windows or other cold surfaces?
• Is there an objectionable odor?

Biological Sources

Excess moisture can cause mold, dust mites and bacteria to flourish. Moist or wet materials should be dried within 24-48 hours to avoid mold growth or replaced if mold already exists.

• Do you see or smell mold?
• Are there signs of rodents or pests?
• Are there animals or pets in classrooms?
• Is condensation often present on windows or cold surfaces?
• Do you see wet or frequently damp areas?
• Is indoor relative humidity above 60 percent?

Building Sources

• Has there been recent:
  • Painting
  • Roofing
  • Remodeling
  • or construction?
• Were there pesticides applied recently?
• Has new furniture, flooring or equipment been installed?
• Are solvents or other chemicals stored in poorly sealed containers?
• Are areas in the building overly dusty?
• Are combustion appliances used in rooms without adequate ventilation?

Housekeeping Sources

• Do complaints occur during or just after housekeeping activities?
• Are chemical or cleaning products used near the complaint area?
• Are any new cleaning products or procedures being used?
• Have there been recent changes in housekeeping procedures?
• Are housekeeping products sufficiently diluted or used based on manufacturers' directions?
• Are products stored in sealed containers and/or in rooms with adequate ventilation?
• Are paints, markers or other art supplies capped or closed?

Local Exhaust

• Is the exhaust system turned on?
• Is the exhaust fan turned on?
• Are the exhaust systems used consistently in special areas (e.g., in science labs or technical shops)?
• Does exhaust move air back into the room rather than outside?¹
• Is a sufficient amount of air being exhausted?²
• Is exhaust ductwork blocked?
• Is a sufficient quantity of air entering the room?¹

Outdoor Air Supply

• Is the ventilation system on?
• Is the airflow from vents sufficient?¹
• Is the airflow through outdoor intakes sufficient?¹
• Are the fans turned on?
• Are outdoor intakes, vents or ducts blocked?
• Are outdoor air intakes near pollutant sources (e.g., idling vehicles or dumpsters)?
• Is outdoor air supply at least 15 cfm per person?²
• Is carbon dioxide (CO2) in the area more than 700 ppm above outdoor concentrations?

Outdoor Sources

• Are sources of odors or pollutants (e.g., vehicle exhaust, stored chemicals or trash bins) located near outdoor air intakes, windows or doors?
• Are there sources nearby or upwind:
  • Exhaust from traffic, loading docks or flues?
  • Industrial, agricultural or lawn care activity?
  • Construction activity?
• Are pollen levels high?

¹ 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
Ducts
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.

²Air Volume: Flowhoods are designed to measure airflow at grilles and diffusers. Pilot tubes are designed to measure air velocity in ducts; air velocity is then used to calculate airflow. While flowhoods are more expensive to purchase than pilot tubes, they are easier to use and can be used to measure airflow in ducts by summing the airflows from all vents connected to a given duct.

Start with the most logical odor source. If odors do not seem to be coming from the immediate area, use chemical smoke to track airflows 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

Excess moisture can cause mold, dust mites and bacteria to flourish. Moist or wet materials should be dried within 24-48 hours to avoid mold growth or replaced if mold already exists.

• Do you see or smell mold?
• Are there signs of rodents or pests?
• Are there animals or pets in classrooms?
• Is condensation often present on windows or cold surfaces?
• Do you see wet or frequently damp areas?
• Is indoor relative humidity above 60 percent?

Building Sources

• Has there been recent
  • Painting
  • Roofing
  • Remodeling
  • or construction?
• Were there pesticides applied recently?
• Has new furniture, flooring or equipment been installed?
• Are solvents or other chemicals stored in poorly sealed containers?
• Are areas in the building overly dusty?
• Are combustion appliances used in rooms without adequate ventilation?

Housekeeping Sources

• Do complaints occur during or just after housekeeping activities?
• Are chemical or cleaning products used near the complaint area?
• Are any new cleaning products or procedures being used?
• Have there been recent changes in housekeeping procedures?
• Are housekeeping products sufficiently diluted or used based on manufacturers' directions?
• Are products stored in sealed containers and/or in rooms with adequate ventilation?
• Are paints, markers or other art supplies capped or closed?

Outdoor Sources

• Are sources of odors or pollutants (e.g., vehicle exhaust, stored chemicals or trash bins) located near outdoor air intakes, windows or doors?
• Are there sources nearby or upwind:
  • Exhaust from traffic, loading docks or flues?
  • Industrial, agricultural or lawn care activity?
  • Construction activity?
• Are pollen levels high?

May be an allergic reaction, if only a small number are affected (check "Biological Sources" first); more likely to be irritation response if a large number are affected (check "Housekeeping Sources," "Outdoor Sources," or "Building Sources" first). Symptoms may disappear when occupant is away from the 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 in use. Also see information for the symptoms: "Cough; congestion; chest tightness; shortness of breath; fever, chills and/or fatigue."

Biological Sources

Excess moisture can cause mold, dust mites and bacteria to flourish. Moist or wet materials should be dried within 24-48 hours to avoid mold growth or replaced if mold already exists.

• Do you see or smell mold?
• Are there signs of rodents or pests?
• Are there animals or pets in classrooms?
• Is condensation often present on windows or cold surfaces?
• Do you see wet or frequently damp areas?
• Is indoor relative humidity above 60 percent?

Building Sources

• Has there been recent
  • Painting
  • Roofing
  • Remodeling
  • or construction?
• Were there pesticides applied recently?
• Has new furniture, flooring or equipment been installed?
• Are solvents or other chemicals stored in poorly sealed containers?
• Are areas in the building overly dusty?
• Are combustion appliances used in rooms without adequate ventilation?

Housekeeping Sources

• Do complaints occur during or just after housekeeping activities?
• Are chemical or cleaning products used near the complaint area?
• Are any new cleaning products or procedures being used?
• Have there been recent changes in housekeeping procedures?
• Are housekeeping products sufficiently diluted or used based on manufacturers' directions?
• Are products stored in sealed containers and/or in rooms with adequate ventilation?
• Are paints, markers or other art supplies capped or closed?

Outdoor Sources

• Are sources of odors or pollutants (e.g., vehicle exhaust, stored chemicals or trash bins) located near outdoor air intakes, windows or doors?
• Are there sources nearby or upwind:
  • Exhaust from traffic, loading docks or flues?
  • Industrial, agricultural or lawn care activity?
  • Construction activity?
• Are pollen levels high?

Due to wide differences in personal comfort levels and clothing, typically up to 20 percent of people in a space may be uncomfortable to some degree – so don't expect to obtain 100 percent satisfaction. Also, occupant discomfort may result from other factors such as:

• Glare
• Noise
• Poor ergonomics
• or job or home stress

Air Temperature and Humidity

• Is the thermostat set properly?
• Is air flowing from the vent too cool or too warm?
• Are drafts or direct sunlight causing discomfort?
• Is the humidity too high or low? (Recommended range is 30-60 percent relative humidity.)
• Does condensation frequently form on windows or other cold surfaces?
• Is there an objectionable odor?

Outdoor Air Supply

• Is the ventilation system on?
• Is the airflow from vents sufficient?¹
• Is the airflow through outdoor intakes sufficient?¹
• Are the fans turned on?
• Are outdoor intakes, vents or ducts blocked?
• Are outdoor air intakes near pollutant sources (e.g., idling vehicles or dumpsters)
• Is outdoor air supply at least 15 cfm per person?²
• Is carbon dioxide (CO2) in the area more than 700 ppm above outdoor concentrations?

¹ 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
Ducts
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.

²Air Volume: Flowhoods are designed to measure airflow at grilles and diffusers. Pilot tubes are designed to measure air velocity in ducts; air velocity is then used to calculate airflow. While flowhoods are more expensive to purchase than pilot tubes, they are easier to use and can be used to measure airflow in ducts by summing the airflows from all vents connected to a given duct.