Construction of a new Science Building, Vassar College Campus, New York, 2013 © Daniel Friedman Indoor Air Quality During Construction
Building IAQ & IEQ Resources, Procedures & Sources of Errors

  • CONSTRUCTION IAQ IEQ - CONTENTS: indoor environmental hazards associated with building construction, renovation, repair, & list of references to IEQ standards & procedures
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IAQ and IEQ during construction & renovation or building cleaning operations:

This article describes the common indoor environmental issues for occupied buildings during construction, renovation, or remodeling and for occupied buildings adjacent to and impacted by such construction projects. We provide references to authoritative information sources giving advice on management of indoor air quality and the indoor environment for construction environments.

Our page top photograph illustrates a large construction project underway on the Vassar College campus in Poughkeepsie, New York in 2013. A new sciences building is under construction on a job site placing major building activity adjacent to an occupied academic building.

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Managing IAQ and IEQ during construction projects

Construction of a new building adjacent to an existing one may raise IAQ and IEQ questions for the exisiting building's occupants (C) Daniel FriedmanWriting in a recent issue of The Synergist, a publication of the American Industrial Hygiene Association, Weekes, Baker and Springston (2004) describe the range of indoor environmental contaminants that may affect the quality of the indoor environment during construction, including airborne particles, VOCs, and in some cases biological contaminants such as mold spores.

[Click to enlarge any image]

Any of these can result in IAQ complaints by building occupants ranging from skin irritation to respiratory or other health complaints and potentially respiratory distress, particularly for people at extra risk such as asthmatics.


What are the Common Indoor Environment or IAQ Hazards Arising During Construction?

IAQ problem source illustration, U.S. EPAAfter citing a number of useful resources (listed below), those authors quoted maximum concentration levels cited in LEEDv4 from the U.S. Green Building Council (USGBC).

That list expands upon the particulate irritants described above to include potentially troublesome contaminants such as carbon monoxide (CO), Formaldehyde, VOCs, Ozone, as well.

The USGBC document describes both recommended maximum concentrations of these contaminants and the test methods used to evaluate their levels in a building.

Illustration at left: NIOSH illustration of sealing penetrations to improve building IAQ. Note that this is one example of multiple coordinated steps that should be taken in concert.

NIOSH in the IEQ article cited below, simplifies the indoor environment concerns arising during construction to three categories:

  1. Biological materials, particularly bacteria, mold, or other microbes that may be present due to leaks, prior sewage spills, or the presence of birds (bird droppings) or rodents, to which I'd add insects and insect allergens (cockroaches or high levels of dust mite fecals).
  2. Particluates such as dusts and fibers (drywall, plaster, concerete, soil, wood, masonry, flooring, roofing, ductwork) and notes that dust may involve irritants (such as fiberglass) and toxic particles such as asbestos or PCBs.
  3. Volatile organic compounds (VOCs) that are found in a wide variety of building products, coatings, and sealants such as adhesives, caulks, cleaners, paints, and in building materials such as carpeting, flooring, and some fabrics, and fuels and their related combustion products.

What are the Common Indoor Hazard Control Measures Used During Construction?

Construction project next to occupied building (C) Daniel FriedmanTo address these potential hazards during a construction project the job managers are invited to prepare and follow an Indoor Air Quality (IAQ) management plan that specifies various control measures such as

  • Controlling the contaminant sources
  • Interrupting the pathways by which contaminants enter the building
  • Protecting the building HVAC system from contamination
  • Cleaning & housekeeping activities
  • Construction work scheduling
  • Occupant relocation

As steel construction continues atop the concrete foundation and walls of this new building underway adjacent to an occupied building (background in my photo), processes include grinding, cutting, and welding operations that may add to airborne particulates.

Where do the SNAFUs Occur during Indoor Environmental Quality Management During Construction or Remediation?

Mold containment falling down (C) Daniel Friedman

I suspect that whether we are monitoring indoor building conditions during construction or before, during and after an asbestos or mold remediation project, among these measures, failures in IEQ management and monitoring usually occur in these areas:

  • Dust containment failures: the original containment barriers are incomplete, poorly constructed, or collapse, fail, or are moved for expedient needs during the construction project. Cross-contamination between the work area and other building areas has often led to a subsequent need for additional cleaning.

    While the use of air handling and ventilation equipment to create effective air pressure differences between building areas is a key step in controlling the indoor environment during construction, I often find cases of misuse of "air scrubbers".

    Often there seems to be a fantasy that an air filtering machine can remove a problem source from a building. This common SNAFU is about as effective as imagining that we can stand in the kitchen and wave our home vacuum cleaner wand in the air to remove dust bunnies from under the living room couch.
  • HVAC protection failures: the HVAC system is operated when it should not be, such as before and during mold remediation work, becoming contaminated, distributing contaminants to other building areas, and requiring additional cleaning of both the HVAC system and the affected areas as a result.
  • Occupant relocation: in a few cases I've encountered occupants who were in my opinion at very high risk (elderly, immune impaired, asthmatic) who were left in high risk areas or even in visibly contaminated areas of homes.

    In a particularly egregious case I inspected a rental home in which an elderly occupant was asthmatic, on continuing oxygen and breathing apparatus, wheelchair-bound, and was sitting in a room where there was extensive visible mold contamination, predominantly Aspergillus versicolor and A. niger, small but harmful particles that are easily inhaled deeply into the lungs.
Mold and yeast in dense contamination on drywall in a home(C) Daniel Friedman
  • Crypto-contaminants: among several thousand inspections and tests of mold-contaminated buildings I found that in many cases the visible mold that had alarmed building owners or occupants was the "tip of an iceberg" of a much larger mold reservoir that was less visually obvious (mold or dust-contaminated insulation, carpets, soft goods) or that was hidden entirely (an extensive mold colonization inside of building wall cavities, often on the cavity side of drywall).

    The photograph at left illustrates mold contamination I found inside of a wall cavity in a building that had already been "mold remediated" by a water damage and mold cleanup company who used a "water extraction" method" to dry out the building.

    One might infer that the method used was not as successful as we'd have hoped.
  • Indoor Environmental Contaminant Test & Inspection Inadequacies: the single most common complaint I have observed among a very large number of readers of our online information about indoor environmental contaminants and IEQ complaints is the casual use of what I consider superficial testing without an adequate building inspection and without adequate interviews.

    Too often a purported "expert" conducts an air test for a contaminant, sends the test sample to a test laboratory, and leaves the building owners and occupants with virtually no useful information.

    In my experience, which is principally with particulate contaminants, the tests used by some investigators and the reports of those results completely fail to acknowledge a stunning range of test variability that arises from even small changes in test conditions.

Mold growth on a pool table (C) Daniel Friedman Mold contamination on pool table under-side(C) Daniel Friedman

Turning a fan on or off, opening or closing a window, or running the ventilation system produce huge differences in the degree to which particulates are airborne. But some less obvious variations in test conditions can still produce several orders of magnitude difference in the detection of indoor contaminants. I have conducted in parallel and in-series tests of airborne particle detection methods to explore these variations.

Air test for mold, particle trace variation (C) Daniel Friedman

Some examples of air test result variation sources & effects include

Image at left: four air samples of airborne particulates in the same location lay down four very different particle traces, illustrating, even to the naked eye, that very different particle levels may be detected depending only on disturbances during the sampling interval.

Yet almost no field practitioner documents these conditions or variables during testing.

[Click to enlarge any image]

  • A room empty of occupants tests very differently than one that is occupied
  • Simply relocating the air sampling appliance at different heights above a floor or at different proximity a problem source produces one to three orders of magnitude difference in the detection of some particles.Two photos above show mold contamination on the under-side of a pool table.

    Placing my Burkard PAS air sampler on the floor under the table, atop the table, and at head-height in the room (about 6 feet over the floor) gave three significantly different particle level results. Waving a notebook at the table top or having someone walk by the table during testing changed the results again.
  • Changes in indoor humidity level produces orders of magnitude difference in the detection of certain indoor spore counts for fungi that vary in spore release as a function of humidity, or temperature, or both
  • Waving my notebook in the air in a room during an air test can alone change the airborne particle count by one to three orders of magnitude.
  • Tapping on the side of an air handler or HVAC duct during airborne particle tests can change the level of detection of particles from an incidental or rare particle occurrence to very high levels of particle occurrence in building air.
  • Tape sampling of moldy surfaces is an appealing test strategy if there is justification for genera/species identification in the first place. But everything depends on where you press the tape. In a mold-contaminated building we rarely find that only one genera/species of mold growth is present.

    At MOLD APPEARANCE on VARIOUS SURFACES I include photographs illustrating that we find completely different mold genera/species growing on the edge of a hollow-core luan interior door than on the door surface - these are two different wood species subjected to otherwise the identical indoor (and mold-contaminated) environment.
  • More of these factors are discussed in detail at AIR TEST FOR MOLD: ACCURACY and at CAUSES of VARIATION in AIRBORNE PARTICLE LEVELS
  • Mold culture tests: Really? Even less reliable in my opinion is the widespread use of culture plates to "test for mold" in buildings. Since 90% of molds won't grow on any culture whatsoever, and since even among those that will grow on a culture some genera/species will overgrow others on the culture plate independent of their original frequency in air, and as particles settle out of air at different rates depending in part on particle mass, this is a rather unreliable approach. See details at MOLD CULTURE TEST KIT VALIDITY.

A result of the failure to understand these very large impacts on building environmental testing is that there is a great deal of confusion between accuracy of test results and the precision with which the results are stated. A mold test lab report may indicate that there were 3478 Aspergillus sp. spores per M3 of air in a test space - a misleadingly precise number - while my tests of particulate variability have indicated that the accurate number can actually range between about 300 spores /M3 and 3,000,000 spores /M3!

Mold spores under the microscope collected from house dust  (C) Daniel Friedman

Low mold counts & False Negatives:

On occasion, particularly when a mold test was conducted in an area a bit distant from a problematic mold reservoir in a building a very low mold count may mask a significant mold contamination problem. The photo at left shows about 20 Aspergillus sp. spores - the only ones present in this sample.

Reporting an indoor count of 20 Pen/Asp spores per M3 of air in a test space would lead most experts to opine that there is no mold contamination problem in the building, claiming that the low mold spore count may be consistent with spore levels in outdoor air - a view that can have merit.

But my interpretation of this image is different. The occurrence of these spores in chains and in a cluster suggests that there is or was a nearby active-growth Aspergillus sp. mold colony. Aspergillus sp. spore chains are quite fragile and break apart quickly in air.

Finding these particular mold spores still bonded in a chain means that there was a reservoir nearby - these spores didn't come in through the window.

In my view this means that there is a significant chance of a false-negative conclusion when screening the indoor environment for airborne particulates and possibly for chemicals as VOCs as well. (See ACCURACY vs PRECISION of MEASUREMENTS).

Importance of effective building inspection & occupant interviews for contaminant sources

In effect, too often either the indoor contaminant test was itself inadequate as a building screen for a hidden problem, or even if the test found indications of an actionable problem, the consultant and test failed to give useful information about what action is needed, failing to answer questions such as Where is the problem source? and What caused it? and How much cleaning is needed?

A strategy of thorough visual inspection, taking of the building's leak history, occupant complaints, and an understanding of building construction, where leaks or moisture traps occur, and what materials are most conducive to problematic mold growth, insect infestation, or probable prior use of chemicals such as pesticides can help find these less obvious indoor contaminant sources before as well as during a construction project so that appropriate containment or other measures can be established.

Useful References for Building Indoor Air Quality and Indoor Environmental Quality During Construction

Weekes et als, (2014) suggested some of these construction IAQ IEQ resources while others are cited from the U.S. EPA IAQ Design Tools for Schools web page.

  • ASHRAE, "Indoor Air Quality Guide: Best Practices for Design, Construction and Commissioning" [download link], ASHRAE Headquarters, 1791 Tullie Circle, N.E. Atlanta, GA 30329 Website:
  • CCA, "Mould Guidelines for the Canadian Construction Industry", Standard Construction Document CCA 82-2004, Canadian Construction Association, 400-75 Albert Street, Ottawa, ON K1P 5E7 Canada, Tel: (613) 236-9455 Fax: (613) 236-9526, retrieved 4/22/14, original source:
  • Donald Weekes, Wayne A. Baker, Jack Springston, "Resources for Managing IAQ during Construction", The Synergist, April 2014, p. 27-30, American Industrial Hygiene Association (AIHA), AIHA, 3141 Fairview Park Drive, Suite 777
    Falls Church, VA 22042, Website: Email: , Tel: 703-849-8888.
  • EPA, "IAQ Design Tools for Schools", U.S. Environmental Protection Agency,
  • EPA, "EPA – IAQ in Large and Commercial Buildings", retrieved 4/20/2014, original source: . This document includes links to several useful documents including the EPA's Building Air Quality Guidance - I-BEAM - IAQ Building Education and Assessment Model, ( and BASE - Building Assessment, Survey and Evaluation Study (
  • "Maintaining Indoor Environmental Quality (IEQ) during Construction and Renovation" [PDF], NIOSH,
  • Minnesota Sustainable Design Guide -
  • City of New York, "High Performance Building Guidelines", April, 1997, city of New York, Department of Design and Construction (PDF, 146 pp., 2.21 M)
  • City of New York, New York City Department of Health and Mental Hygiene – Guidelines on Assessment and Remediation of Fungi in Indoor Environments, [PDF], retrieved 4/20/14, original source
  • SMACNA, "IAQ Guidelines for Occupied Buildings Under Construction", 2nd Ed., (2007), Sheet Metal and Air Conditioning Contractors' National Association, 4201 Lafayette Center Drive Chantilly, Virginia 20151-1219, Tel (703) 803-2980 - Fax (703) 803-3732, Website:
    Excerpt from the documents Forward:

    The IAQ Guideline is intended to be an authoritative source for providing project management guidance in maintaining satisfactory indoor air quality (IAQ) of occupied buildings undergoing renovation or construction. The Guideline covers how to manage the source of air pollutants, control measures, quality control and documentation, communication with occupants. It includes example projects, tables, references, resources, and checklists.

    The previous edition of the IAQ Guideline is referenced by the U.S. Green Building Council’s LEED Green Building Rating System for Existing Buildings and New Construction. SMACNA recommends the guide to architects, engineers, construction managers, facility managers and building owners who will be involved in construction activities inside occupied buildings.

    Additionally, the principles presented here are also applicable to IAQ problems encountered in occupied areas of buildings during the final phases of new construction.
  • U.S. Green Building Council, "Reference Manual for LEED Green Building Rating System (Commercial, Version 2)", U.S. Green Building Council, 2101 L Street NW, Suite 500, Washington D.C. 20037, USA, Tel: 800-795-1747, Website:


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