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Indoor Air Quality for Sustainable Buildings -- for useful and reliable feature articles, for the latest news and events listings. Check out our links to the best information on Indoor Air Quality and Sustainable Buildings on the web. Our "events" page links you to IAQ and to Sustainability meetings and conferences all over the world.We invite your suggestions and comments on our resources related to indoor environmental quality, architecture, healthy buildings, and the built environment's impacts on the sustainability of human settlements.  

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Fungal secondary metabolites as harmful indoor air contaminants

Extremely important: newly published article by J David Miller and David R. McMullin, “Fungal secondary metabolites as harmful indoor air contaminants: 10 years on.” Appl Microbiol Biotechnol, DOI 10.1007/s00253-014-6178-5. For me personally, the paper makes a strong case for the link between airborne chemicals and their relationship to moldy buildings and human health.

Increases the already strong evidence that damp buildings are risky.

Abstract “From the epidemiological studies conducted on the
effect of mould and dampness on health a decade ago, the role
of toxin-producing fungi in damp and mouldy buildings involved
opinion more than evidence. Very little was known
about the metabolites that were produced by the fungi that
grew on damp building materials, and almost nothing had
been reported on their occurrence in buildings. As a consequence,
the focus was on speculations involving the fungal
toxins that occur in agriculture. Over the past decade, particularly
in the last 5 years, considerable progress has been made
concerning the relevant toxins from fungi that grow on damp
building materials. This paper summarizes the available data
on the low-molecular-weight toxins reliably known from fungi
common on damp building materials, the toxins that have
been measured on mouldy building materials and the new
understanding of the role that they play in the documented
health effects of individuals living and working in damp and
mouldy buildings.”

from the Conclusions:
“‘nontoxic strains’ of S. chartarum sensu lato were producing
atranones which, although are not cytotoxic, are potently inflammatory
(Rand et al. 2006).”
“The development of high-resolution LC-MS/MS methods
has allowed the determination of fungal toxins on building
materials (Nielsen and Frisvad 2011) and in settled dusts (e.g.
Täubel et al. 2011).”

“Finally, a diverse array of metabolites from
fungi common on building materials and triple-helical glucan
have been tested for their effects on lung biology in relevant
animalmodels. These have revealed that toxin doses that could
be achieved in damp residential housing modulate genes that
are in asthma pathways.”


“The next decade of research will illuminate the significance of this information.”



Airborne transmission of Ebola?


 I have been wondering whether Ebola could be transmitted through air. I posted a couple of tweets asking about it but got no responses.

Now the a solicitation for the Defense Threat Reduction Agency has raised this question.

It contains a provocative description of the potential for airborne transmission: ” Filoviruses are able to infect via the respiratory route and are lethal at very low doses in experimental animal models, however the infectious dose is unknown.” ( p. 7, HDTRA1-15-EBOLA-BAA.pdf — DEFENSE THREAT REDUCTION AGENCY, BROAD AGENCY ANNOUNCEMENT, HDTRA1-15-EBOLA-BAA, October 24, 2014)

The implications of recognition of the potential for airborne transmission are quite large as was illustrated during the 2009 swine flu outbreak in Mexico City when the government closed most public and private facilities. The economic consequences are so significant that the decision becomes as much a political one as a public health concern. Just look at how the politicians in America are using handling of Ebola in the run-up to the imminent elections.

Here (below) is a provocative text excerpt, this from a 1999 publication (“An Introduction to Ebola: The Virus and the Disease” C. J. Peters and J. W. LeDuc. Journal of Infectious Diseases 1999;179 (Suppl 1). ix–xvi This article is in the public domain.)

For me, the implication for those of us who work in the area of health and buildings, the potential for aerosolization of the contents in a toilet bowl by flushing means that all toilet rooms used by infected individuals must be negatively pressurized and the exhaust must go outside. While this is the universal guidance for design and operation, the question is whether it is reasonably well executed in most buildings. My experience of investigation air quality concerns in only a few public and privately owned hospitals is that many of them have design, construction, or operational deficiencies. A public health response would be to require verification that negative pressure is maintained in these compartments since we know that toilet flushing results in aerosolization of some of the bowl’s contents.

Even then, as Yuguo Li showed with his analysis of the the SARS outbreak at Amoy Gardens, negative pressure and exhaust directly to the outdoors might not be enough. In the case of a very infectious agent, intake of the contaminated outdoor air in a downwind building can lead to many more infections.
1. Li et al, 2004. Predicting Super Spreading Events during the 2003 Severe Acute Respiratory Syndrome Epidemics in Hong Kong and Singapore. Am. J. Epidemiol. (2004) 160 (8): 719-728. doi: 10.1093/aje/kwh273;
2. Li et al, 2005. Role of air distribution in SARS transmission during the largest nosocomial outbreak in Hong Kong. Indoor Air, 15(2),83–95,
3. Li et al, 2007. “Role of ventilation in airborne transmission of infectious agents in the built environment – a multidisciplinary systematic review. ” Indoor Air 17(1), 2–18.

Beyond that, what about nasal and oropharyngeal secretions? Linsey Marr’s work shows how difficult experimental and epidemiology studies are due to the differences in the vehicle (e.g., mucus, saliva, or water) and that simple analyses of T and RH are not sufficient without specificity to the vehicle of interest.

Here are some questions for those of us on the Building Science/Ventilation side and those on the public health side to ponder:
What can ventilation systems do?
What can hospital (and other public facility operators) do?
What can public health officials do (besides quarantine potentially infected individuals?)
What can researchers do?

 “Indeed, during the 1989–1990 epizootic of the Reston subtype of Ebola, there

was circumstantial evidence of airborne spread of the virus, and supporting observations included suggestive epidemiology in patterns of spread within rooms and between rooms in the quarantine facility, high concentrations of virus in nasal and oropharyngeal secretions, and ultrastructural visualization of and abundant virus particles in alveoli [17, 50].”

 (source: An Introduction to Ebola: The Virus and the Disease” C. J. Peters and J. W. LeDuc. Journal of Infectious Diseases 1999;179 (Suppl 1). (The Journal of Infectious Diseases 1999;179(Suppl 1):ix–xvi.)

Reference 17. Peters CJ, Johnson ED, Jahrling PB, et al. Filoviruses. In: Morse S, ed. Emerging viruses. New York: Oxford University Press, 1991:159–75.

Reference 50. Jahrling PB, Geisbert TW, Jaax NK, Hanes MA, Ksiazek TG, Peters CJ. Experimental infection of cynomolgus macaques with Ebola-Reston
filoviruses from the 1989–1990 US epizootic. Arch Virol Suppl 1996; 11:115–34.

Also see reference 65. Roels TH, Bloom AS, Buffington J, et al. Ebola hemorrhagic fever, Kikwit, Democratic Republic of the Congo, 1995: risk factors for patients without a reported exposure. J Infect Dis 1999;179(suppl 1):S92–101.

Also, of interest in an economically-driven decision-making governance system: “Threat of Lawsuit Could Test Maine’s Quarantine Policy”


Mold odor linked to asthma

Joouni Jaakkola's group in Finland has published three studies linking mold odor to upper respiratory effects. In a letter to the editor of the journal Chest, the group summarizes their findings with respect to asthma. You can read the letter at the Chest journal web site here

You can find the letter and a lot more information on indoor microbiology and the indoor environment in our special new section Indoor Environment and indoor microbiome.


State of California Releases an Important New Green Building Document CALGreen

The State of California Department of General Services released their policy that provides direction to state agencies that build, lease and operate state buildings, on reducing indoor pollutant levels and ensuring healthful indoor environments for occupants in new, renovated, leased, and existing state buildings, as directed in Governor’s Executive Order B- 18-12 and the Green Building Action Plan.

To read more about and download the document, click here.

Indoor Environment and indoor microbiome

Check out our new feature full of resources for studying the indoor microbiome here.

We will be adding resources to help researchers and professionals who want to study the indoor microbiome with an emphasis on culture-independent methods. We will share the results of our work during the past three years with funding from the Alfred P. Sloan Foundation through the microBEnet project at the University of California.

Our site will supplement (and complement) the web site with information intended primarily for those who want to understand the indoor microbiome as part of the building as an ecosystem.

Nothing exemplifies the building as an ecosystem or the usefulness of the construct "building ecology" better than the complex dynamics of the built environment and the indoor microbiome. We hope this additional resource will assist those eager to advance our understanding of the indoor microbiome as a "normal" and important (essential?) part of the indoor environment.

Please send us your comments and suggestions, references, and other resources you would like us to share with other visitors to our site.

If you haven't signed up yet for our eUpdates, a newsletter that will let you know when new resources are added, you can do so at the link at the top of the right hand column of this page.

Indoor Environment and indoor microbiome database -- available for free download.

More than 360 articles that contain information on the indoor microbiome and the indoor environmental conditions reported by the authors. Full abstracts are included. The database is in MS Access format and simple or complex queries can be made using the database in Access. We are looking for ways to make it more widely available. It was supported by the Alfred P. Sloan Foundation's grant to UC Davis' microBEnet project, Jonathan Eisen PI. We also have prepared a How-to file for those not familiar with constructing searches in databases. It is also downloadable. You can downloaded it from the article entitled "How to use the Indoor Environment-Indoor microbiome database."

Click here to download the database
Click here to download the how-to file
Click here to download the database curation process   

Click here to get the spreadsheet version


Click here for Bibliographic info with abstracts_in pdf_140619

UPDATE Do mold and/or dampness "cause" asthma or allergic responses?

A recent paper by Choi et al (as a belated tail to the tale of the Swedish Dampness and building health (DBH) study, claims to provide further evidence of a lack of connection between mold exposure and asthma outcomes. (Choi, H., Byrne, S., Larsen, L. S., Sigsgaard, T., Thorne, P. S., Larsson, L., Sebastian, A. and Bornehag, C.-G. (2014), Residential culturable fungi, (1-3, 1-6)-β-d-glucan, and ergosterol concentrations in dust are not associated with asthma, rhinitis, or eczema diagnoses in children. Indoor Air, 24: 158–170. doi: 10.1111/ina.12068). 

If you read the paper, also read all three letters to the editor. 

Rylander, R. (2014) Fungi in homes - how do we measure? Indoor Air 24, 221-222

Choi, H., Thorne, P.S., Sigsgaard, T., Bornehag, C.G. (2014) Response to Rylander. Indoor Air 24, 223-224

Miller, J. David: Re: Choi et al. Indoor Air 24:158, Indoor Air 24:221       

Also read the earlier publicaiton on the DBH study: 

Bornehag, C. G., Sundell, J., Bonini, S., Custovic, A., Malmberg, P., Skerfving, S., Sigsgaard, T. and Verhoeff, A. (2004), Dampness in buildings as a risk factor for health effects, EUROEXPO: a multidisciplinary review of the literature (1998–2000) on dampness and mite exposure in buildings and health effects. Indoor Air, 14: 243–257. doi: 10.1111/j.1600-0668.2004.00240.x

There is another view held by the majority of researchers that dampness and mold are associated with asthma and allergy and that efforts to control moisture are essential and of great  health importance..

We are hoping to start a dialogue on this subject here and solicit your comments, relevant references, and suggestions for improving the dialogue.

Please send your comments and we will post them in a thread on-line so that the discussion can be an open one.



NPR Animation of the Human Microbiome

A video from NPR about the human microbiome that is worth taking a look at.

Quick tips

Quick tip:  Why do people living in damp buildings get sick? Is it the mold, the bacteria, or the combination?

The scientific evidence for a connection to moisture is the strongest. There is some evidence for certain species of mold and bacteria but it is generally far weaker for mold and bacteria. An exception, of course, is Legionella p, the cause of Legionnaire's Disease, but exposure to Legionella p. may not be dominated by bacteria found in the air.  There is increasing evidence that  molds and bacteria are  involved together, not as separate "causal factors." Scientific studies that look for associations between only mold or only bacteria may not find strong associations. Moisture is clearly relevant to the microbial exposures causing the reported health effects.

Quick tip:  What is the  biggest mistake have we made over the past 30-40 years that we should not repeat if possible?

I think it may be the separation of ASHRAE Standard 62 (Ventilation and IAQ) and Standard 55 (thermal comfort). Both IAQ and thermal comfort are affected by and ought to be addressed by the same building design and operational solutions. ASHRAE Guideline 10-2011 tries to get at these connections and interactions for the first time anywhere, well, except for papers I wrote a long time ago. ASHRAE Guideline 10, now available for purchase on the Publications

page of the ASHRAE web site, brings together a lot of what we know about the interactions and also discusses interactions with light and noise. There is far less known than we would like, but far more known than we tend to reflect in our standards, codes, and practices. If you know of some other connections, please send us an email. We will be grateful for your help.


ASHRAE Indoor Air Quality IAQ Design Guide Now Available for Free

The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) is now making the IAQ design guide and all of its reference materials available to the public at no cost through its web site. 


The Indoor Air Quality Guide: Best Practices for Design, Construction and Commissioning is designed for architects, design engineers, contractors, commissioning agents, and all other professionals concerned with indoor air quality.


Click here for more information.

Microbiology of the built environment

Everywhere we turn there are microbes (living organisms so small we cannot see them without magnification): in our cars, houses, offices, water pipes, and in every nook and cranny of our bodies.  Most are harmless, but some can make us sick or cause other damage.  Some even play a role in protecting us and our creations from the depredations of others.  Most of these microbes are still unknown and uncharacterized.

Over the last 20-30 years scientists have made revolutionary progress in understanding microbes in so-called “natural” systems. We have studied microbes in oceans, soil, and hotsprings, as well as those that live on and inside plants and animals. Little attention however has been paid to the microbes that live in the “unnatural” indoor world around us: in our buildings, planes, trains, and cars, where most of us spend more than 90 percent of our lives.  These are the microbes of the “built environment”. 

Thanks to continuing advances in DNA sequencing technology, and a recent initiative by the Alfred P. Sloan Foundation, this gap in knowledge is beginning to be addressed. The effort to better understand the built environment has implications for engineering and architecture, biodefense and forensics, and has even produced the concept of probiotics for buildings. 

Building Ecology - A short course

It is common to assume that buildings are simply inanimate physical entities, relatively stable over time. This implies that there is little interaction between the triad of the building, what’s in it (occupants and contents), and what’s around it( the larger environment). We commonly see the overwhelming majority of the mass of material in a building as relatively unchanged physical material over time. In fact, the true nature of buildings can be viewed as the result of a complex set of dynamic interactions among their physical, chemical, and biological dimensions. Buildings can be described and understood as complex systems. Research applying the approaches ecologists use to the understanding of ecosystems can help increase our understanding.[1]  “Building ecology “ is proposed here as the application of those approaches to the built environment considering the dynamic system of buildings, their occupants, and the larger environment. Read more...


Feature Articles

Moving Beyond TVOC - Reasons to avoid the use of TVOC as Pass/Fail criterion for assessing VOC emissions from products

by Al Hodgson, Co-founder and Research Director, Berkeley Analytical Associates

Total Volatile Organic Compounds (TVOC) has a long history as a metric for determining the acceptability of the emissions of VOCs from building products and furnishings. The first significant program to rely on a TVOC criterion was the Carpet & Rug Institute’s (CRI) Green Label Program that evolved out of the Carpet Policy Dialog between the carpet industry and the US EPA. The TVOC criterion was later incorporated into the U.S. Green Building Council’s LEED rating systems and was adopted by the commercial furniture industry. More recent VOC emission test method and acceptance standards have focused instead on individual VOCs that may pose health hazards to individuals at low concentrations. Examples of such programs in North America are the California Department of Health Services' Standard Practice (a.k.a. Section 01350), which recently was revised to Standard Method Version 1.1, and CRI’s Green Label Plus program. TVOC values are still reported, but pass/fail determinations are based on the emission levels of individual compounds of concern. There is an urgent need to expand such determinations of acceptability beyond a select number of individual VOCs to encompass the broader range of chemical emissions that may impact health. TVOC is again being proposed to fill this gap and may be appealing to many because of its presumed simplicity. In my opinion, we should avoid this temptation and move on the more difficult, but certainly achievable, task of focusing on the toxicity of individual compounds. The following are my primary arguments against the use of TVOC as a Pass/Fail metric.  Read more...


EnergyPrinciplesEnergy Principles in Architectural Design

By Ed Dean was published in 1981 by the California Energy Commission to provide a basis for California’s licensed architects to learn about energy. The California State Board of Architectural Examiners was considering a continuing education requirement for license renewal, and it was thought that the guide could be the basis for the exam.  Read more...



ozoneOzone, Filters, and SBS symptoms

If outdoor ozone levels are related to SBS symptom prevalence in a building, would it be wise to install filters to remove the ozone entering the building? If using synthetic fiber filters further increased SBS symptom prevalence as outdoor ozone levels increased, would you want to use some different material for your building's particle filters?

Recently published research on the results suggest that it may reduce SBS symptom rates if you reduce ozone remove ozone from outdoor air.

VR2Target Resources and Emissions Budgets for Healthy and Sustainable Buildings - slideshow

Sustainable buildings are more than an assortment of "green building" features. Building design and actual performance must be compared to benchmarks or targets for a truly sustainable environment in terms of resource consumption and pollution emission.

California Greenhouse Gas Tool for Buildings

California's Greenhouse Gas (GHG) tool for California is now available on the web -GHG Tool for Buildings in California. The tool is publicly available and free for download.

This is a major step forward, the first tool that provides time- and weather-resolved GHG emissions calculations.   Read more...

IAQ and Plants

plantiaq The idea that plants clean indoor air is a sad, continuing saga fed by bad science, commercial interests, and wishful thinking. I published an article in the Indoor Air Bulletin

on the subject in 1992 (available on this web site) that provides some details.

Take home message:

1.   Don't use plants to improve IAQ. They don't. If anything, they pose risks to good IAQ.

2.   There is no credible scientific evidence that plants improve IAQ. The planting media has been hypothesized to be responsible for pollutant removal in some studies. The planting media alone can be expected to contribute to a limited reduction in some airborne chemical concentrations.

3.   Most advocates of indoor plant use have been funded by or are themselves providers of plants or supporting systems.

4.   If plants are used indoors for aesthetic reasons, there should be extra care to avoid moisture problems or problems with fertilizers and pesticides, all known sources of indoor air quality and health problems.





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