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Knowledge base of an IAQ investigator

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Table 1. Categories

Human Physiology
Human Physiology


IAQ and biology

IAQ and physics

IAQ and material sciences
Material Sciences

IAQ and earth sciences
Earth Sciences

ASTM D 7297 – 06 Standard Practice for Evaluating Residential Indoor Air Quality Concerns

The IAQ relationship triangle
The IAQ relationship triangle outlines the process for influencing the occupants with pollutants. Some will recognize this is the epidemiological triangle.

social principles
The social principles and expectations between industry and consumers.

Health issues related to Architecture, Interior Design and HVAC systems

6 Strategies for IAQ

Damage Hierarchy - Causes

Indoor Air Quality - A Competency Overview
Copyright 2009 (c) Robert Bean, R.E.T, P.L.(Eng.), All World Rights Reserved, originally published in HPAC Canada, May/June 2009 Issue, A Rogers Media Publication

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Defining the skill sets of a competent IAQ investigator all depends on the
investigation. In reality, there is no one single IAQ specialist.


Indoor air quality (IAQ) is one of six metrics which when combined with others, influences the total definition of indoor environmental quality (IEQ).

IAQ in of itself is not a proxy for IEQ which is written as:



     TCQ = Thermal comfort quality
     IAQ = Indoor air quality
     ISQ = Indoor sound quality
     ILQ = Indoor lighting quality
     IOQ = Indoor odor quality
     IVQ = Indoor vibration quality

Items of Competency

Indoor Air Quality - A Competency Overview

IAQ investigations can be simple and basic requiring low to moderate skill levels, or complex and anomalous requiring several IAQ investigators with different and advanced abilities.

We will focus on the general practitioner involved in residential construction noting that these skills sets apply to all types of projects. As a bare minimum, a generalist in IAQ investigations should have an adequate background in indoor environmental quality, which call for a basic awareness of human physiology, chemistry, biology and physics as well as material and earth sciences. With these knowledge areas, the investigator should understand the relationships between the various outdoor and indoor environmental concerns influencing the occupant.

Table 1 organizes a list of topics that the IAQ practitioner should cover when doing basic investigations. The examples given are by no means complete but are provided to indicate the scope of knowledge required. Investigators should also have basic skills in interviewing techniques, building design and construction practices; basic understanding of heating and cooling systems and appliances; use of IAQ measurement equipment; interpretation of IAQ data; and technical report writing.

Interviewing Techniques

The objective of the interviewing process is to elicit occupant responses for the purposes of gathering information which can be used later to develop hypotheses. This process requires professional communications meaning that verbal dialogue and written reports may be legally regulated. This is especially true if the investigation is part of a legal proceeding or where property and personal harm has occurred. Government legislation regarding the collection and sharing of personal information must also be considered and respected. It is important that the professional interviewer understands that they should not attempt to manipulate or lead the conversation in directions that may be construed as self serving, as might be the case of an investigator with interests in selling filtration or dehumidification equipment.

Building Design and Construction Practices

Excluding discussion on post construction occupant operation of a home, the source of many IAQ problems can be attributed to the land development, poor designs including choices in materials and faulty assemblies. In order to understand the problems with an existing building, the investigator has to understand what constitutes good design and construction practices. All of the items in Table 1 find themselves somewhere in the study of construction.

 HVAC and Appliances

Unless proven otherwise, an IAQ problem will become an HVAC problem regardless of the cause. This is why the IAQ generalist has to be aware of all the other potential elements so he/she can reduce the list of concerns through a process of elimination. The HVAC systems and appliances may very well be the cause and solution. For this reason the investigator should be aware of the principles of HVAC design and operation. This includes ventilation standards, and the capabilities and limitations of various air quality equipment such as filtration, humidification and dehumidification devices.

IAQ Measurement Equipment

The generalist should be able to identify the simplest of IAQ challenges with basic instrumentation. This might include handheld devices for measuring particulate, carbon monoxide, temperature, pressure and moisture or they might include passive samplers for sampling such things as radon. Some may also have the skills to use blower doors and thermography equipment. These are all building and material science-related devices and should be part of one’s inventory of investigative tools. Beyond the application of these basic tools are instruments and samplers used by field and laboratory personnel who usually specialize in industrial hygiene or microbiology.

Interpretation of Data

Results from basic instruments are immediate and can be interpreted during the investigation. However, having the results and interpretation does not provide cause. For example, a high moisture reading from basement flooring can verify a reason for mould but it won’t identify the source of the moisture. So the use of measurement tools goes hand in hand with one's overall knowledge base.

Technical Report Writing

The investigator will need to organize and report on the findings and recommendations in a well thought out, clear and concise format. This document might just be exchanged between the occupant and investigator to complete the terms of the contract or it could very likely find itself as evidence in legal proceedings. The quality of the report in terms of its presentation, technical accuracy, thoroughness, grammar and spelling will serve as a perpetual record representing the professionalism of the individual involved in the investigation. Poorly written reports, including those that are inaccurate, misleading or self serving are a reflection of the investigative firm–it is best to approach every communication as if the document or dialogue will at some point become public domain.


The above provides an outline of basic competencies for a general practitioner in IAQ investigations and is by no means exhaustive. It does not for example discuss skills needed for corrective measures or the application of safety precautions needed during investigations. These come through years of training and experience.


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