Sick Building Syndrome | Fungal Exposure Assessments
By Dr. Harriet Burge, EMLab Chief Aerobiologist and Director of Scientific Advisory Board
Sick Building Syndrome (SBS) is a term commonly used for non-specific symptoms that are temporally related to occupancy of a particular building. When building-related symptoms are characteristic of a specific clinical entity, they are called Building Related Illness (BRI). These illnesses are varied, and include Legionnaires' disease, building related hypersensitivity pneumonitis, building-related asthma, and others.
SBS symptoms include mucous membrane irritation (cough, scratchy throat, stuffy sinuses, and itchy eyes), headache, fatigue, difficulty concentrating, and other non-specific symptoms. The causes of SBS vary with the building and its occupants. SBS was once called "Tight Building Syndrome" and was considered to be a result of excess tightening of buildings in response to energy use concerns. However, many buildings with an excess of symptoms among the occupants are well ventilated. Still, increase in ventilation rates is often the "cure" for the problem.
Some people consider that SBS is caused not by the physical environment, but, rather, by psychosocial factors. Gender, lack of control, poor management, too much work, too little work, perceived housekeeping quality, and many other social factors have been blamed for the symptoms. In some cases, psychosocial factors may be the major cause of complaints. However, clearly, in some cases, environmental factors are at fault.1 For example, paper dust, and photocopier use have both been related to increases in complaints in a dose-dependent way.2 An excess of volatile organic compounds have been blamed for SBS symptoms.3 However, one study attributed this effect to the perception of odors at VOC concentrations far below those that would be likely to have an effect.4 These authors discuss the possibility that reactive chemistry might produce irritants that might be responsible for some symptoms.
Mold contamination has clearly been related to cases of BRI.5, 6 However, its relationship to SBS is less clear. A Swedish study documented that dampness in residential buildings was associated with SBS symptoms with symptoms increasing with the number of dampness indicators present. Whether or not mold growth was responsible for these symptoms remains unknown.7 An extremely interesting study exposed people to measured doses of airborne fungal spores from growth on building materials. In this study, symptoms were similar among the two fungi studied AND for the placebo tests, indicating no specific effect of the spores.8 Mycotoxins have not been measured in quantities sufficient to cause the normal SBS symptoms, and the data regarding the role of mycotoxins in indoor air remain equivocal.9
Review of Mold toxicity cases:
1. Mendell MJ, Fisk WJ, Stafford M, Marmot M, J Eley M, Stansfield S. Is health in office buildings related only to psychosocial factors? * Authors' reply. Occup Environ Med 2007; 64:69-70.
2. Jaakkola MS, Yang L, Ieromnimon A, Jaakkola JJK. Office work exposures and respiratory and sick building syndrome symptoms. Occup Environ Med 2007; 64:178-184.
3. Sunesson A, Rosén I, B Stenberg, Sjöström M. Multivariate evaluation of VOCs in buildings where people with non-specific building-related symptoms perceive health problems and in buildings where they do not. Indoor Air : 2006; 16:383.
4. Wolkoff P, Wilkins CK, Clausen PA, Nielsen GD. Organic compounds in office environments - sensory irritation, odor, measurements and the role of reactive chemistry. Indoor Air 2006; 16:7-19.
5. Hoffman RE, Wood RC, Kreiss K. Building-Related Asthma in Denver Office Workers. American Journal of Public Health American Journal of Public Health J1 - American Journal of Public Health 1993; 83:89-93.
6. Patterson R, Mazur N, Roberts M, Scarpelli D, Semerdjian R, Harris K. Hypersensitivity pneumonitis due to humidifier disease: seek and ye shall find. Chest 1998; 114:931-933.
7. Engvall K, Norrby C, Norback D. Sick building syndrome in relation to building dampness in multi-family residential buildings in Stockholm. International Archives of Occupational and Environmental Health 2001; 74:270-278.
8. Meyer HW, Jensen KA, Nielsen KF, KildesÃ¸ J, Norn S, Permin H, Poulsen LK, Malling HJ, Gravesen S, Gyntelberg F. Double blind placebo controlled exposure to molds: exposure system and clinical results. Indoor Air 2005; 15:73-80.
9. Kallili B, Bardana E. Inhalational mold toxicity: fact or fiction? A clinical review of 50 cases. Annals of Allergy Asthma and Immunology 2005; 95:239-246.
By Dr. Harriet Burge, EMLab Chief Aerobiologist and Director of Scientific Advisory Board
Human Health Effects
Fungi evolved over 400 million years ago and references to mold in buildings suggest that it has always been present in human environments. At present there is growing public concern about the potential health effects of mold in homes and structures that has been heightened by media reports of presumed health effects, clear episodes of illness related to indoor fungal growth, litigation, and requirements for disclosure during real estate transactions.1
In addition to health concerns, fungi may cause decay of building materials and contents, occasionally to the extent that the material must be removed from the building. Some of this growth may be hidden inside of attics and walls, making visible diagnostics difficult (Gravesen, Nielsen et. al.).2 Exposure assessment must then rely on sample collection.
Exposure Assessment vs. Environmental Assessment
We often consider these two topics the same, whereas they may not be. Exposure assessment essentially means that your focus is on human exposure, and you are going to have to interpret your data with respect to the amount of exposure people are experiencing. Environmental assessment, on the other hand, is used to test hypotheses regarding whether or not there is fungal growth, the nature of the growth, and its extent without regard to exposure. Most of the incidental investigations that are done are environmental assessments and the data cannot be interpreted with respect to human exposure. Evaluating human exposure for these studies would require information such as the time each person spends in the environment, what activities he/she performs, and a number of other factors. If you want to do exposure assessment, then you must write hypotheses that ask specific questions about exposure, not just environmental conditions.
Hypothesis Development and Testing
The advantage of generating a hypothesis and writing it down is that you can then focus your investigation on answering that specific question. This focus leads to an investigation structure that produces data that can be interpreted specifically with respect to the question, and you can decide in advance how that interpretation will be done.
Interpreting the Data
So, you have your data as a result of testing a specific hypothesis. You can then ask the question: "Do the data support your hypothesis or not?" If you have not done a hypothesis driven investigation, then you will have to rely on existing guidelines and standards. These simply do not exist for fungi and fungal aerosols in indoor environments.3 You might be able to make reference to a baseline data set such as the EMLab MoldScore™ (designed for paired indoor/outdoor spore trap data). Otherwise, you might be able to find an appropriate data set in the literature that was collected using the same methods that you used.4
Developing a Sampling Strategy
Many studies aim to determine whether or not fungi are growing in an environment, and whether or not aerosols are being produced. In this case, visual assessment, tape or bulk samples, and a limited air sampling protocol are often sufficient for this determination. The most straightforward method for air sampling, the spore trap, is generally used, and data are compared indoors and out. If viability of the airborne organisms is of interest, then a cultural method is used. This type of investigation is most commonly done using a sieve plate impactor (Biocassette™, Andersen, etc.). A good discussion of bioaerosol sampling instruments can be found in the ACGIH Air Sampling Instruments manual.5, 6 The following table offers a list of sampling approaches and analytical approaches along with the questions each might be used to answer.
|Sample Collection Methods||Direct Microscopy||Culture||Chemical Assay|
|Tape samples||Identification of visible material as fungal growth; some ID possible. Not quantitative||Identification of dominant organisms present. Not quantitative.||N/A|
|N/A||Identification of dominant organisms present. Semi-quantitative.||Quantitative for specific chemicals (including allergens) present|
Measured area samples yield data per unit of area
|General nature of the dust. Not quantitative||Identification and enumeration of culturable organisms present||Quantitative for specific chemicals (including allergens)|
|Volumetric air samples||Enumeration of microscopically identifiable fungal spores by genus and/or type||Enumeration and identification of fungi that can grow under provided conditions||Quantitative for specific chemicals (including allergens)|
1. Seltzer JM, Fedoruk MJ. Health Effects of Mold in Children. Pediatric Clinics of North AmericaChildren's Health and the Environment: Part II 2007; 54:309-333.
2. Gravesen S, Nielsen PA, Iversen R, Nielsen KF. Microfungal contamination of damp buildings--examples of risk constructions and risk materials. Environ Health Perspect.; 1999; 107:505–508.
3. Rao CY, Burge HA, Chang JC. Review of quantitative standards and guidelines for fungi in indoor air. J Air Waste Manag Assoc 1996; 46:899-908.
4. MacIntosh DL, Brightman HS, Baker BJ, Myatt TA, Stewart JH, McCarthy JF. Airborne fungal spores in a cross-sectional study of office buildings. J Occup Environ Hyg 2006; 3:379-389.
5. ACGIH. Air Sampling Instruments: ACGIH, 2001:752 pgs.
6. HPDP BoHPaDP. Damp Indoor Spaces and Health: Institute of Medicine (IOM), 2004.
This article was originally published on April 2007.