chapter six Biological contaminants — mold Biological contaminants were described in Chapter 5 in the context of illness syndromes and disease risks associated with exposure to airborne organisms and products of biological origin. Discussion of airborne bacteria and viruses was in the context of their role in causing infectious disease and potentially contributing to other problems; mites, insects and animal allergens, in the context of causing chronic allergic rhinitis and asthma. Because mold is such a significant indoor environment concern, this chapter is devoted to mold- related health concerns and risk factors for mold infestation. I. Biology of mold The terms mold and mildew are commonly used to describe the visible manifestations of the growth of a large number of organisms that are scien- tifically classified as fungi. Terms such as yeast and mushrooms are used to describe, respectively, single-celled fungi (widely used for baking and brew- ing) and the large reproductive structures of a major class of fungi that are used for food or are known for their high toxicity. Fungi form true nuclei, which distinguishes them from lower organisms such as bacteria. They differ from plants in that they do not produce chlo- rophyll and thus cannot manufacture their own food; from animals in that (except for reproductive cells in some species) they are not motile. Structurally, fungi exist as masses of threadlike filaments or hyphae. The collective mass of hyphal filaments is described as mycelium, the vegetative part of the organism that infests a substrate and extracts food for the organ- ism’s growth. Though hyphal filaments are microscopic, the mycelium is typically visible to the naked eye. Masses of mycelia can be distinguished as fungal colonies (Figure 6.1). In many species, the hyphae are colorless; in other species they contain pigments. © 2001 by CRC Press LLC [...]... T., Indoor Air Quality — A Comprehensive Reference Book, Elsevier, Amsterdam, 1995, chaps 6, 31 © 2001 by CRC Press LLC Sorenson, W.G., Mycotoxins: toxic metabolites of fungi, in Fungal Infections and Immune Responses, Murphy, J.W., Friedman, H., and Bendinelli, M., Eds., Plenum Press, New York, 1993, 469 Spengler, J.D., Samet, J.M., and McCarthey, J.F., Eds., Indoor Air Quality Handbook, McGraw-Hill... place In the psychometric chart in Figure 6. 7, a volume of air that has a dry bulb temperature of 75°F (23.5°C) will condense water at approximately 66 °F (18.5°C) if the absolute humidity is 0.013 lbs H2O vapor/lb dry air; condensation will occur at approximately 60 °F (15.5°C) if the absolute humidity is 0.011 lbs H2O vapor/lb dry air © 2001 by CRC Press LLC Figure 6. 7 Psychrometric chart Condensation can... autumn season of leaf and other plant decay Such mold spores are deposited on indoor surfaces and, on resuspension, affect indoor airborne levels for some time after additional spores no longer intrude into indoor spaces in any significant way Indoor airborne mold levels and subsequent human exposure can also occur when mold-infested materials are brought into building spaces Sources may include infested... 1990, 1 36 Chmel, H., Fungal infections in the immunocompromised host: clinical syndromes and diagnosis, in Fungal Infections and Immune Responses, Murphy, J.W., Friedman, H., and Bendinelli, M., Eds., Plenum Press, New York, 1993, 405 Etkin, D.S., Biocontaminants in Indoor Environments, Indoor Air Quality Update, Cutter Information Corp., Arlington, MA, 1994 Federal–Provincial Committee on Environmental. .. in Public Buildings: A Guide to Recognition and Management, Health Canada, Ottawa, 1995 ISIAQ Guideline, Control of Moisture Problems Affecting Biological Indoor Air Quality, International Society of Indoor Air Quality and Climate, Milan, Italy, 19 96 Kurup, V.P and Fink, J., Fungal allergy, in Fungal Infections and Immune Responses, Murphy, J.W., Friedman, H., and Bendinelli, M., Eds., Plenum Press,... terreus Outbreaks of nosocomial (hospital-acquired) aspergillosis have been associated with new construction as well as renovation activities Life-threatening fungal infections in immune-compromised and other patients are often associated with Candida spp Candida grows in a yeast-like fashion and is a normal part of the microflora of humans As such, filtration Table 6. 4 Pathogenic and Opportunistic Fungal... observed, they are typically dominated by Aspergillus or Penicillium or both IV Health concerns Exposure to airborne mold and mold-produced environmental contaminants may pose significant health risks to humans These include well-known mycotic diseases as well as other less well-defined health effects There are three basic categories of mycotic disease: infections, allergenic/immunological illness, and nonallergic... severe These events represent worst-case scenarios of building mold infestation, associated exposure and health risks, and mitigation requirements © 2001 by CRC Press LLC F Other sources of indoor mold contamination Mold contamination of indoor spaces can occur even in the absence of high relative humidities, water intrusion, or flooding Since high mold levels occur outdoors, indoor spaces can be contaminated... are not easily measured in environmental samples except by bioassay procedures Though they are likely to be ubiquitous in suspended aerosols both in indoor and outdoor air, little information is available on the range of airborne glucan concentrations indoors III Exposure assessments Numerous studies have been conducted to assess airborne mold levels in both outdoor and indoor environments These studies... of 40 houses 3 Water vapor-generating sources Relative humidity in buildings can be influenced by a variety of factors These include the use of vapor-generating sources such as swimming pools, © 2001 by CRC Press LLC spas, steam baths, large fish tanks, and decorative recirculating fountains, pools, waterfalls and streams The higher the surface area and temperature of vapor-generating sources, the higher . include: 3-methylfuran, hep- tanone, 1-octen-3-ol, octan-3-ol, 2-octen-1-ol, octen-3-one, octan-3-ol, 2- methyl-1-butanol, 2-hexanone, geosmin (1,10-dimethyl- trans -9 -decalol), ace- tone, 2-butanol,. trisulfide, methanol, 1-propanol, 4-decanol, 2- methylisoborneol, trimethylhexane, 3,3-dimethyl-2-oxetanone, 3,3-dimethyl- 1-octene, ethyl 2,4-dimethylpentone, and 2-methoxy-3-isopropylpyrizine 2-octen-1-ol. This compound, as well as 1-octen- 3-ol, 2-hexanone, and light alcohols, tends to be associated with water- damaged materials. Fungal VOCs, reported as total MVOCs, range in con- centration