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Diagnosing and Solving IAQ Problems: Checking Potential Causes

Having developed some hypotheses about potential causes from examining clues suggested by the "what," "where," "when," and "who" of the problem, do some simple checks to see if the problem is obvious. Examples below suggest some things to check in looking at common sources or causes.

 

Potential Cause Things to Check
Mold
  • A musty smell suggests the presence of mold.
  • Relative humidity should be below 60% at all times.
  • Check for visible mold, standing water, or moist material in the complaint area (carpet, walls, ceiling tile).
  • Check for evidence of condensation on windows or cold surfaces.
  • Check for lack of adequate housekeeping in the affected area?
  • Check pipe entries into the area that trace back to the basement or crawl space.
  • Check for signs of mold or standing water, or moist material in the air handler, ductwork, crawlspaces, or basements.
  • Drain pans should be clean and draining.
  • Filters should be clean and dry. If filters have not been changed in a long while because they are not sufficiently loaded, they may have developed mold. Try changing them anyway.
  • Check return ducts that pass through a crawlspace, basement, or moist area for any potential leaks.
  • Check for roof leaks, plumbing leaks, or ground drainage problems.

Excess moisture or humidity can foster mold/fungi, dust mites, and some bacteria.
Particles
  • Check if anyone is smoking in the area suggesting the need to ban or enforce smoking policy.
  • Make sure that the smoking lounge is properly isolated and ventilated.
  • Check for major indoor particle sources such as a printing shop indicating the need to control emissions.
  • Check for visible dust, especially in high or hard to access areas, indicating the need for improved housekeeping.
  • If vacuuming occurs during occupancy, try using high efficiency vacuum filtration or a change in vacuuming schedule to non-occupied hours. Periodically use deep extraction cleaning of carpets.
  • Check to see if outdoor air vents are near vehicle sources or other particle sources.
  • Check the filters and filtration system and consider increasing filter efficiency?
  • Use walk off mats in entryways to keep dirt out.

Particles can themselves be harmful, and may contain chemicals that are harmful. Source control, good housekeeping, and filtration can be effective strategies.
Housekeeping Sources
  • Check schedules to see if complaints occur during or just after certain housekeeping activities.
  • Check to see if any new housekeeping products or methods were introduced just prior to symptom onset.
  • Check for changes in personnel applying housekeeping products or methods prior to onset of symptoms.
  • Check to insure that housekeeping products are used as directed
  • Check for proper storage of housekeeping products stored nearby.
  • Check to insure that housekeeping products are mixed properly, and at proper strength.

Housekeeping is important to good indoor air quality, but it also contains the potential for creating indoor air quality problems.
Building Sources
  • Check to see if there had been recent painting, roofing, remodeling or pesticide application just prior to the onset of symptoms.
  • Check for installation of new furniture or partitions just prior to onset of symptoms.
  • Make sure that outdoor air supply during startup occurs prior to occupancy.
  • Insure that outdoor air supply adequate during all operating modes. Check outdoor air operating mode just prior to and during symptom occurrence.
  • Insure that outdoor air flush of building contaminants occurs during unoccupied hours.

Source control for major building sources , protocols during remodeling and renovation, and adequate outdoor air strategies for general sources are important dimensions of controlling building source contamination.
Outdoor Sources
  • Check for changes to surrounding land use that could pollute the outdoor air near the building.
  • Check for changes to building services, such as trash removal, loading dock, and parking areas, landscaping, or storage areas that could contaminate the outdoor air at the outdoor air intake.
  • Check pollen levels when symptoms occur.
  • Check construction activity nearby.

Important outdoor sources can be building related, traffic related, land use related or vegetation related. Source type, source location and wind direction are important considerations.
Sewer Gas or Similar Odor
  • Check for signs of a sewer leak.
  • Check building sanitary vents in proximal relation to the outdoor air intake.
  • Insure there is water in all traps.
  • Check pathways (e.g. pipe chases, ducts) that could be delivering sewer gases into occupied areas.

Soil gases, including radon, can enter the building through the basement foundation, and odors from drain traps and sanitary vents should be controlled.
Outdoor Air Supply
  • Make sure that ventilation system is turned on, and that outdoor air grilles are not blocked.
  • Insure that air is coming out of the room air supply vent(s) in the complaint area, and that all controls, including pneumatic controls, are working properly.
  • Check that outdoor air dampers are operating properly.
  • Make sure that air is flowing into the outdoor air intake.
  • Check that time clocks are properly set (e.g. readjusted during daylight saving).
  • Make sure that economizer and freezer controls are functioning properly–turning on and off at the proper times.
  • Make sure that the supply and return fans are tracking properly.
  • Make sure that the VAV system provides a sufficiently high % of outdoor air during part load to insure adequate outdoor air under part load conditions.
  • Make sure system is balanced.

Outdoor air dilutes contaminants from all sources. The ventilation system should provide sufficient outdoor air to all occupied spaces during all operating modes.
Air Handling Unit

Also see Outdoor Air Supply.

 

  • Make sure that the mechanical room is clean and free of any stored materials.
  • Insure that filters are clean and properly installed.
  • Make sure that drain pans are clean, properly sloped and draining.
  • Make sure that coils are clean.
  • Check for any leaks in mechanical equipment or ducts.
  • Make sure combustion flues are in good condition.
  • Make sure there is no backdraft from combustion flues under worst case conditions.

 

The air handler is at the heart of the ventilation system. All parts must be functioning well under all operating modes, clean, and protected from microbial growth.

Local Exhaust
  • Insure that exhaust is turned on when needed.
  • Insure that the exhaust fan is drawing air.
  • Insure that air is coming out of exhaust vents on the roof.
  • Insure that the source located so that the exhaust draws contaminants away from rather than toward occupants.
  • Make sure that the exhausted room is under negative pressure where make up air easily enters the room.

Local exhaust can be an effective means of controlling stationary local sources, but they must be properly located and operational.

Diagnosing and Solving IAQ Problems: Checking Potential Causes

Created on November 22nd, 2011.  Last Modified on January 15th, 2015

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