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IAQ Reference Guide

Section 5 - Diagnosing IAQ Problems

IAQ reference guide, section 5
The goal of diagnosing an IAQ problem is to identify the cause of the problem and implement an appropriate solution. Often, more than one problem can exist, requiring more than one solution. For this reason, EPA created the Problem Solving Checklist (Appendix A: "IAQ Coordinator’s Forms" in the IAQ Coordinator’s Guide) and the IAQ Problem Solving Wheel (a separate tab of the Action Kit). For best results, it is also important to have good background knowledge of the basics of IAQ as outlined in Sections 1 and 2.

The IAQ diagnostic process begins when a complaint is registered or an IAQ problem is discovered. Many problems can be simple to diagnose, requiring a basic knowledge of IAQ and some common sense. If the cause (or causes) of the IAQ problem has already been identified, proceed to the solution phase outlined in Section 6: "Solving IAQ problems."

Not all occupant complaints about IAQ are caused by poor indoor air. Other factors such as noise, lighting, and job-, family-, or peer-related stress can — individually and in combination — contribute to a perception that IAQ is poor.

How to Diagnose Problems

The Problem Solving Checklist and the IAQ Problem Solving Wheel are your primary tools for finding solutions to problems. They will help simplify the process and lead the investigation in the right direction.

Start with the Problem Solving Checklist and encourage school staff to answer questions or perform activities posed by the checklist and the wheel. Pollutant sources and the ventilation system may act in combination to create an IAQ problem. Resolve as many problems as possible and note any problems that you intend to fix later.

Once you identify the likely cause of the IAQ problem, or the solution is readily apparent, refer to Section 6: "Solving IAQ Problems," for potential courses of action.

IAQ Reference Guide Home
Sections
1: Why IAQ is Important to Your School
2: Understanding IAQ Problems
3: Effective Communication
4: Resolving IAQ Problems
5: Diagnosing IAQ Problems
6: Solving IAQ Problems
Appendices
A: Hiring Professional Assistance
B: Basic Measurement Equipment
C: Codes and Regulation
D: Asthma
E: Typical Indoor Air Pollutants
F: Secondhand Smoke
G: Radon
H: Mold and Moisture
I: Emissions from Motor Vehicles and Equipment
J: Portable Classrooms
K: Integrated Pest Management
L: Resources
M: Glossary and Acronyms

Spatial and Timing Patterns

As a first step, use the spatial pattern (locations) of complaints to define the complaint area. Focus on areas in the school where symptoms or discomfort have been reported. The complaint area may need to be revised as the investigation progresses. Pollutant pathways can cause complaints in parts of the school that are located far away from the source of the problems. See the tables below.

After defining a location (or group of locations), look for patterns in the timing of complaints. The timing of symptoms and complaints can indicate potential causes and provide directions for further investigation. Review the data for cyclic patterns of symptoms (e.g., worst during periods of minimum ventilation or when specific sources are most active) that may be related to the HVAC system or to other activities affecting IAQ in or near the school.

SPATIAL PATTERNS OF COMPLAINTS

SUGGESTIONS
Widespread, no apparent spatial pattern
  • Check ventilation and temperature control for entire building.
  • Check outdoor air quality and outdoor sources.
  • Identify sources that are spread throughout the building (e.g., cleaning materials, contaminated HVAC systems, overcrowding, furnishings).
  • Check for distribution of a source throughout the ventilation system.
  • Consider explanations other than air contaminants.
Localized (e.g., affecting individual rooms, zones, or air handling systems)
  • Check ventilation and temperature control within the complaint area.
  • Identify pollutant sources that may affect the complaint area (e.g., copy room, storage closet, smoking lounge, mold/moisture).
  • Check for contamination of the local HVAC system.
Individual(s)
  • Check for drafts, radiant heat (gain or loss), and other localized temperature control or ventilation problems near the affected individual(s).
  • Check local sources (see above) and consider that common sources may affect only susceptible individuals.
  • Consider the possibility that individual complaints may have different causes. If symptoms continue when occupants leave the building, there may be non-building related causes.

TIMING PATTERNS OF COMPLAINTS

SUGGESTIONS
Symptoms begin and/or are worst at the start of the occupied period
  • Review the operation procedures for the HVAC system.  Pollutants from building materials or from HVAC system itself, may build up during unoccupied periods.
Symptoms worsen over the course of the occupied period.
  • Investigate whether ventilation is adequate to handle routine activities or equipment operation within the building, and that temperature and humidity are properly controlled.
Intermittent symptoms
  • Look for daily, weekly, or seasonal cycles or weather-related patterns in maintenance or cleaning activities.
  • Check linkage to other events in and around the school.
  • Make sure the HVAC system is operating properly, including during extreme weather.
Single occurrence of symptoms
  • Consider spills and other isolated events as sources.
Recent onset of symptoms
  • Check for recent changes or events (e.g., remodeling, renovation, redecorating, HVAC system adjustments, leaks, or spills).
Symptoms relieved on leaving the school, either immediately, overnight, or (in some cases) after extended periods away from the building
  • Consider that the problems may be building-associated, though not necessarily due to air quality. Other stressors (e.g., lighting, noise) may be involved.

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