The indoor environment is contaminated by the products of microbial growth, such as spores, allergens, volatile organic compounds, endotoxins, mycotoxins and so on.
According to some estimates, between 10 and 50 per cent of indoor spaces across Asia, Australia, Europe and North America are affected to some degree by dampness. The presence of dampness in indoor spaces shows wide variations across different climate zones. The problem is more acute in the high-humidity conditions prevailing in areas close to the coast or in river valleys and basins.
Microorganisms are everywhere, but the availability of moisture in or on materials is particularly conducive to the propagation of a whole range of microbes, from fungi, to actinomycetes and other bacteria. In addition to these favorable conditions, dust provides an adequate supply of nutrients to sustain extensive microbial growth. Materials that retain moisture and accumulate dirt easily provide the optimal conditions for rapid growth of these organisms. As a result of this, the indoor environment is contaminated by the products of microbial growth, such as spores, allergens, volatile organic compounds, endotoxins, mycotoxins and so on. While it has not yet been possible to conclusively prove a causal relation between these products to adverse health effects, persons with atopic and allergic symptoms are hypersensitive to biological and chemical agents found in damp indoor conditions. Research is also bringing to light the detrimental effects of damp environments on atopic individuals as well. In this section, we will provide a brief summary of some important varieties of microorganisms known to be particularly active in damp indoor environments.
Agents that induce the production of antibodies can also potentially generate allergic reactions. Allergens can include both dead matter (such as mite excreta) as well as microorganisms (such as mold spores and bacteria)
. Damp environments usually exhibit a high concentration of high-relative molecular-mass allergens such as dust mites and fungal allergens.
1.1.1 Dust Mite Allergens
Dust mites are a predominant source of inhaled allergens
, with Dermatophagoides pteronyssinus
and Dermatophagoides farinae
being the most common species amongst them. D. pteronyssinus
produces proteases (known as Der p I and Der p II) that are found in high concentrations in fecal matter. Der f I, produced by D. farinae
is commonly found in house dust and bedding in damp spaces.
1.1.2 Fungal allergens
Fungal species are associated with the production f type I, type III and combined type III and IV allergens. Immunoglobulin (Ig)E sensitization to common fungal species such as Alternaria
and Cladosporium spp
.is strongly linked with allergic respiratory diseases like asthma. Fungi belonging to common genera like Penicillium and Aspergillus, which can be found in most home environments
, are known agents of IgG-inducing type III allergens. Prolonged, high-concentration exposure to fungi has also been connected to the eruption of rare conditions like hypersensitivity pneumonitis.
In some species, spores, hyphae and fungal fragments are glycopeptides with enzymatic properties. They are more active during germination and mycelial growth
and draw attention to the significance of viability of spores for allergenic expression. Even though non-viable spores produce allergens at lower concentrations their significance should not be underplayed, as they contain potentially harmful compounds including (1→3)-β-D-glucans and mycotoxins.
Many varieties of fungi reproduce through spores that are adapted to dispersal through aerosolization
. These spores remain in the air for long durations and come to be deposited in the respiratory system. Fungal cell fragments contain mycotoxins as well allergens. Being smaller than spores, they enter the respiratory tract with greater ease than spores, which vary between 2-10 μm in length. The rate of aerosolization of spores and fungal fragments depends on a number of factors, including wind speed, time of day, humidity levels, colony structure, desiccation stress and so on.
Some studies have looked at the presence of bacteria such as Streptomycetes and mycobacteria in damp indoor conditions
. Streptomycetes are Gram-positive, spore-forming actinobacteria. They are soil organisms that produce some toxins such as valinomycin. Streptomycetes is often found on damp or wet surfaces.
Mycobacteria have also been found to be present in damp buildings, their concentration increasing with the extent of fungal damage Exposure to mycobacteria can induce an inflammatory response, while components of the cell wall of mycobacteria are immunogenic.
While the concentration of total viable bacteria indoors ranges between 101-101 CFU/m3 (Colony Forming Units per cubic meter), normal levels for Streptomycetes and mycobacteria have not yet been established.
Endotoxins are toxins on the cell wall of bacteria, which are released during the process of cell lysis. They are integral parts of the outer cell membrane Gram-negative bacteria and are made up of proteins, lipids and lipopolysaccharides. High-concentrations of endotoxins can cause respiratory difficulties, such as non-allergic asthma, while exposure to the same in low or moderate concentrations can protect against asthma and allergies. Studies have also proposed an association between endotoxins and the onset of rheumatic diseases
. Significantly, airborne endotoxin levels show only a moderate variation across geographical differences. It is reasonable to expect Endotoxin levels to be higher in damp conditions, but this has not been the case in a study conducted in some areas affected by hurricane Katrina and subsequent flooding no such correlations were observed.
(1→3)-β-D-glucans form the structural cell wall components of most fungi and some bacteria. They are non-allergenic and water-insoluble made up of glucose polymers. These cell components are known to influence immune response and are detrimental to respiratory health
. While it has not yet been possible to standardize methods to study (1→3)-β-D-glucans concentrations, there is some indicative research in the field. According to some studies, (1→3)-β-D-glucans levels in damp buildings with fungal infestations have been recorded as varying between 10 and 100 ng/m3
, and at around 1 ng/m3
in dry indoor spaces.
Mycotoxins are biomolecules of low relative molecular mass produced by fungi, and may in some instances have toxic effects on animals as well as humans. Mycotoxins affect the process of RNA synthesis and can cause damage to DNA. Some mycotoxins like aflatoxin from Aspergillus flavus and Aspergillus parasiticus are known to have carcinogenic effects
. While many mycotoxins are known to be immunotoxic, others are immunostimulating at low levels of exposure. Mycotoxins generated by S. chartarum
and Aspergillus versicolor
may be found in most buildings with ongoing or past water damage. Mycotoxins such as macrocyclic tri-chothecenes have been found in much higher concentration in floor dust and on walls in buildings with mold, even though their air concentrations showed no statistical difference from those in unaffected houses. While it may be reasonably conjectured that mycotoxins are present in higher concentrations in damp spaces, no conclusion can be drawn on whether these concentrations are high enough to have adverse effects on the health of occupants.
1.6 Volatile Organic Compounds
Many species of fungi produce volatile compounds that are comparable to common chemicals intended for industrial use. Over 200 such compounds have been identified, but this offers little practical use since few of these are specific to fungi alone
. Damp indoor environments may sometimes lead to emissions of volatile organic compounds from damp and moldy building materials, which pose significant health risks. For instance, volatile organic compounds such as 2-ethyl-1-hexanol are released through chemical degradation of the plasticizer in polyvinyl chloride floor coatings and glues, which is accelerated by damp concrete floors.
There is no conclusive evidence to demonstrate the increased risk of viral infections in damp indoor conditions. It has been conjectured that high-humidity environments can extend the survival times of viruses affecting the respiratory tract
, with heightened risk of infection and even onset of allergies. While some evidence is available on the significantly higher rates of survival of common cold viruses in damp conditions, these findings have been experimental in nature.
2. The Morphology and Ecology of Fungi
Mold, fungal spores and cell fragments contain a number of allergens and mycotoxins, which may have adverse effects on human health. The ubiquitousness of these microorganisms and their affinity for dampness make them a major nuisance in indoor environments.
The available research on the effects of fungi on human health and the physical environment being relatively sparse, we will begin by looking at some basic characteristics of fungi, namely, the morphology of various varieties, their modes of reproduction, their ecologies and their cell by-products. This will enable a fuller appreciation of the complexities that may be expected in any process of assessment and remediation of mold-related problems.
Ordinary indoor environments have some amount of airborne mold spores at all times. Given the natural process of interchange of air, it is not at all unusual to detect indoors the presence of fungal spores that are also to be found in the outside environment. It is normal to detect a similar variety and concentration of spores in both indoor and outdoor environments in a given place
. But the presence of different species and higher concentrations of mold spores indoors is usually an indication of the amplification of mold. Such amplification of mold can usually be traced to accelerated growth of mold on substrate materials kept indoors. Such colonization by mold destroys substrate materials and releases volatile, toxic compounds. This, along with the higher concentration of allergens, leads to a deterioration of air quality. The effects of this are felt more acutely, but not exclusively, by hypersensitive, atopic individuals.
2.1 Classifying Varieties of Fungi
The commonly used term mold
does not have any specific taxonomic significance. Rather, it is an umbrella term akin to gardeners™ use of weeds. It is used as an everyday term to signify any colony of fungal growth visible in an indoor environment. Another non-technical term ismildew
, which usually refers to visible growths on wood, clothes and so on.
Mycologists define fungi as non-chlorophyllic, eukaryotic organisms, whose cells are protected by a rigid wall composed of glucans and chitin. Fungi are unique in that they possess characteristic of both plants as well as animals
. Fungi are usually classified according to the relationships derived from evolutionary biology.Most fungi are placed under three categories, namely: Zygomycetes, Ascomycetes, and Basidiomycetes. Fungi belonging to the Ascomycetes group are most commonly found in fungal infestations in buildings.
2.2 Sustaining Ecologies
While some fungi are embedded in their ecology through parasitic or symbiotic relationships, most are saprophytic. Saprophytic fungi grow by producing acids and enzymes
that react with the organic components in substrate materials to activate chemical reactions that supply the organism with nutrients. In this sense, fungi play an important ecological role in the degrading of waste. Fungi can take on a whole range of forms from single-celled yeast to microscopic hyphae and spore-producing basidiomycetes. As we shall see in the following sections, some varieties of fungi, and specific cell components are connected with adverse health effects.
2.3 Optimal Conditions
The availability of suitable nutrition, along with other factors such as optimum humidity, light, oxygen availability and ambient temperature play a significant role in determining the specific form and life stages of fungi. For instance, in some species the abundance of light leads to the production of spores rather than mycelial hyphae. Fungi can also grow in a wide range of temperatures while most fungi find temperatures between 15°C-30°C (59°F-86°F)
to be optimal, others like thermophiles exist in the range of 35°C -50°C (95°F -122°F).
Fungi can draw nutrition from virtually any organic material wood, dust, paint, paper, leather and so on. For this reason, fungi can form colonies on a whole range of substrate materials including carpets, walls, tiles and even dirt on glass. Various species, however, may show a preference for some materials. For instance, Stachybotrys has an affinity for cellulose substrates
and attacks wallpaper and paperboard.
This variability in its life stages induced by differences in conditions makes it difficult to infer the true distribution of mold in indoor spaces from tests on cultures from growth surfaces. Provided with appropriate conditions some fungi may produce toxins, even though they may not do so in other conditions
. This is further complicated by the seasonal cycles that characterize fungal growth.
In so far as fungi always have access to abundant sources of nutrition, it is usually the availability of moisture
that is the determining factor in the amplification of mold in indoor spaces. Consequently, areas exposed to leakages or moisture condensation are particularly susceptible to extensive mold growth. At the same time, even high levels of humidity without wetness or heavy condensate is enough for colonization by fungi such as Aspergillus and Penicillium. Some studies have identified these as varieties that cause or aggravate health problems in building occupants.
2.4 Modes of Reproduction
Most fungi reproduce asexually through mitosis to form extensive colonies. Fungi survive unfavorable conditions by becoming dispersed in the form of spores
, which can then produce complete organisms upon finding more suitable conditions for growth. While some spores are able to stick to surfaces, others are easily aerosolized. Mold spores can be dispersed by natural means such as wind or through human actions such as dusting, etc.
2.5 Other Fungal Products
Mold products include structural components such as glucans as well as various chemicals and volatile organic compounds (VOCs) that are released in the process of substrate decay. In addition fungi may also produce a range of secondary metabolites
. Fungal byproducts can induce immunologic, toxicological and allergenic among human subjects. While these processes have not yet been fully understood, it has been possible to identify some specific fungal metabolic reactions and their effects on humans. These documented effects range from antibiotic, to psychoactive, and toxic.
2.6 Some Common Varieties of Mold
Listed below are a few common varieties of fungi that are encountered in everyday environments. While some of these affect agricultural produce meant for human consumption, others attack household materials and objects. A few varieties are also known to produce potent allergens and mycotoxins that may have adverse health effects for humans.
- Acremonium strictum is a moisture-loving fungus and one of the most common species of mold. Materials such as drywall, wood and paper provide a suitable substrate for their rapid growth.
- The Alternaria genus is comprised of about 20 species that are host-specific parasites. A saprophytic fungus that attacks weakened plants, it also produces mycotoxins. It finds its way indoors through plant-based materials such as seeds, wood and pulp, foodstuff and soil. It can also be found on other substrate materials such as textiles. These fungus species, however, are seldom found indoors.
- The Aspergillus genus is made up of some 150 species. A producer of significant mycotoxins, Aspergillus varieties are known to cause illness amongst people and animals. A. fumigatus is known to cause violent allergic reactions in humans. A. flavus, another common species that is often found on grain and foodstuff, is known to produce aflatoxin. A. niger can be found on a number of indoor household objects such as textiles, seeds and objects damaged by water. The optimum temperature for A. niger is 20°C-40°C, due to which it grows easily in indoor environments. It is most commonly associated with fungal damage in books and paper products. Industrial applications of A. niger have been developed, and they are used in the production of many enzymes as well as citric acid.
- Chaetomium is an ascomycetes genus that is also known to cause extensive damage to books and wood products.
- The genus Penicillium is made up of over 250 different species, and their correct identification demands the expertise of an experienced mycologist. Some species have been observed to produce mycotoxins, while others are pathogen of citrus fruits. P. roquefortii and P. camemberti are used for cheese production.
- Stachybotrys chartarum is classified as a hydrophilic fungus that is found on cellulose-based materials. S. chartarum produces hemolysin as well as mycotoxins such as trichothecene. A high presence of S. chartarum in indoor spaces is often associated with complaints about air quality in dwelling and working spaces.
- Trichoderma fungi grow in both indoor as well as outdoor environment and are found on materials such as soil, seeds, timber paper and textiles. T. koningii, T. harzianum, and T. viride are species commonly found inside buildings and homes. They produce slimy, green spore masses that produce strong musty odors in closed indoor environments like unventilated rooms. They also produce mycotoxins like trichothecene.
3. Mold and Material Damage
Fungi infestations cause incremental damage over time, such that the longer the period of exposure, the greater the damage. This can be in the form of deep structural damage to substrate material, or as cosmetic damage due to staining.
3.1 Water Intrusion
A study by the US Center for Disease Control conducted an extensive survey of homes in the New Orleans area damaged by water during hurricane Katrina. The study found that toxin-producing fungal growth was always to be found in these houses. About 50 per cent of the homes evidenced the presence of Chaetomium
. Additionally 25 per cent of the houses were afflicted with the infamous black mould, Stachybotrys
, which produces the neurotoxic and cytotoxic Satratoxin. Similarly, the neurotoxic agent Trichothecene, produced by Trichoderma
, was found in every fourth home. Finally, every house visited in the study showed concentrations of various strains of the toxic Aspergillus
Wood-rotting fungi can cause wide-spread damage to wooden buildings. Serpula lacrymans
, a variety of wood-rotting fungus, is commonly found in temperate climates in Australia Japan and Europe. This fungus causes extensive wood decay and is acknowledged as one of the most destructive species of dry-rot fungus
3.2 Household Objects
Mold can grow on a whole range of substrate materials provided by ordinary household objects. Different varieties may be found on materials such as clothing, books, leather, and even paint and adhesives. Fungi, being highly opportunistic in their search for nutrients, usually attack the most easily digestible part of a given object. This results in selective damage to substrate materials
. For instance, even fungi that do not consume cellulose can damage paper, books etc by leaving the cellulose fiber unharmed even as they attack the starch and protein available in the media and binding materials.
Colonies of fungal growth often cause staining and coloration of substrate materials
. In some instances, this may be due to the release of colored pigments by the fungi. In others, the metabolic process produces a number of chemicals as byproducts that cause discoloration reactions on the substrate. It has also been observed that the color of the stain also depends on the substrate material itself, since the availability of nutrients and other suitable conditions can alter the morphology of the organism. For instance, Penicillium frequentas
can produce both yellow as well as pink stains. Further, staining is more common in mature fungi colonies, and is more prominent in those parts characterized by a deterioration of older hyphae filaments. Stains are usually not a problem when a fungus culture is removed before it matures.
3.3 Related Public Litigation
The material damage caused by fungi growth can amount to heavy financial costs in the form of renovation, maintenance and replacement of affected buildings as well as household objects. While the health effects of fungi may not have been conclusively established yet, employers are increasingly facing insurance and litigation claims from worker™s claiming long-term damage to their health alleged to have been caused by occupational exposure to mold. The risks of mold exposure have received wide publicity with a number of celebrities being diagnosed with Stachybotrys
-related disease. These, along with other incidents have lead to high-profile litigation against builders and contested insurance claims.
4. Mold and Human Health
Mold exposure can affect humans through three mechanisms heightened immunological response, toxic-irritant effects of fungi byproducts, and direct infection. This section will provide a brief summary of the functional mechanisms that have been identified in various species of fungi. An understanding of these is useful in diagnosis and treatment of patients who may be suffering from mold-induced health problems
. The associated illnesses are organized under the following categories: respiratory diseases, skin infections and allergies, immunological effects, toxic reactions due to ingestion, and some other highly specific diseases traceable to fungi.
4.1 Pathways of Exposure
Indoor air quality
in damp buildings is highly compromised, and comprises of a host of microbial agents. It is difficult to pinpoint the relation between specific fungi and illnesses because the chemical composition of the air is constantly changing, with reactions occurring between byproducts of different microorganisms as well. But it may be suggested that given the high incidence of respiratory difficulties in damp and moldy environments, the airways are the main route of exposure to spores, their fragments and their byproducts. Most mold spores that enter the airways
are deposited in the upper airways, comprising of the nose and the epiglottis.
is another pathway of exposure to mycotoxins produced by some species of fungi. These usually enter the digestive system through food products such as grains, poultry products, fruits and so on. These mycotoxins enter the bloodstream by being absorbed in the digestive tract. Additionally mycotoxins also cause damage to the digestive system itself by destroying gut microflora, owing to their properties of mycotoxins. While mycotoxins such as Aflatoxin are quickly absorbed across the intestinal barrier, others such as Gliotoxin (produced by yeast as well as Aspergillus
) can attach themselves to the intestinal lining. Mycotoxins that remain unabsorbed may be deposited in the digestive and intestinal tract, and lead to high concentration of toxins. While healthy individuals usually remove such mycotoxins from their body through excretion, mold-sensitive persons exhibit a tendency to retain them in their gut microflora or in other organs in the body.
A provocative hypothesis also argues that with regard to the toxicological properties of fungi, the distinction between inhaled and ingested mold toxins is false and untenable. Rather, the principal route of exposure to all mold toxins is through the digestive tract and not the airways.
It is argued that most inhaled spores come to be deposited in the mucous lining of the upper airway. The airway is cleared when the mucous is removed to the digestive tract for excretion. Thus, it may be suggested that effective exposure to inhaled spores also takes place through the gut rather than the lungs. The common occurrence of digestive disorders alongside other mold-related illnesses lends some credence to this view.
4.2 Mold and Disease
The World Health Organization report on dampness and mold[i]
presented a comprehensive review of research on the health effects of exposure to mold. According to the report, conclusive evidence was available to define the relation between indoor dampness
and a range of adverse effects on respiratory health
, such as asthma development and exacerbation, infections, wheezing and dyspnoea. Research on the relation between dampness and allergic rhinitis has come up with varied results, while its relation with bronchitis remains inadequate.
The review finds that there is very strong epidemiological evidence of a causal role of indoor dampness and mold in asthma exacerbation. As many as 21 per cent of current asthma cases may be attributed to indoor dampness and associated mold exposure. For all other respiratory health effects there is insufficient evidence of a causal relationship. Further, sufficient clinical evidence supports associations between fungi
and hypersensitivity pneumonitis
and allergic alveolitis
. Toxicological studies also show associate mold spores with a range of inflammatory, immunological and cytotoxic effects in subjects.
These results, however, must be read in the light of the inherent limitations in data collection and analysis. But at the same time, the adverse health effects of dampness-induced mold in indoor environments must be taken seriously even in the absence of standardized tests and methods.
4.3 Respiratory Diseases
4.3.1 Fungi-induced Allergic and Hypersensitivity Reactions
The ability of fungi to cause allergic reactions in human is well established. So much so, in some countries local news reports offer regular updates on mold spore as well as pollen counts along with the weather report. Mold antigens are routinely tested for when delineating the sensitivity profile of atopic patients.
Antigens or antigenic epitopes
are proteins and glycoproteins that constitute structural components of the cell, its enzymes and metabolic byproducts. In sensitized individuals, the body responds to the allergens with the production IgE, IgG and IgM antibodies. While most fungal antigens elicit immediate Gell and Combs type I responses, others are also known to activate delayed type III and type IV allergic reactions. Sensitization to fungal allergens usually takes place over repeat exposures to high ambient concentration of sensitizing antigens. Far lower concentrations, however, are adequate for inflammatory symptoms to appear in the reactive phase.
4.3.2 Asthma and Allergic Rhinitis
There is sufficient clinical evidence to suggest that mold is a major trigger in atopic, hypersensitive patients. Prolonged exposure
to mold has also been associated with the onset of perennial rhinitis. Occupants in moldy environments are likely to develop such symptoms, with the risk of sensitization
It is now accepted that asthma and allergic rhinitis have similar pathophysiological mechanisms. Type I responses of asthma and allergic rhinitis are among the most common illnesses reported in relation to mold exposure. These responses begin with sensitization on initial exposure, and inflammatory responses in the mucosal membranes on subsequent instances of re-exposure to allergens. Inflammatory responses follow the pattern of subsequent re-exposures. In time, these symptoms become more aggravated, with inflammatory responses becoming more chronic and less particularized. It becomes increasingly difficult over time to identify the causative allergens.
Initial exposure to allergens is followed by phagocytosis of the antigenic macromolecule by an antigen-presenting cell (APC). Antigen epitopes are then exteriorized onto the membrane surface proteins, which leads to the secretion of interleukin-1 (IL-1). TH
2 lymphocytes related to that epitope then react with the antigen fragment, resulting in the production of interleukins (IL-4 and IL-5). IL-4 and IL-5 stimulate the production of IgE antibodies and eosinophils, respectively. The IgE antibodies attach on to basophils and mast cells, eventually moving into the nasal mucus membrane and the pulmonary interstitium and resulting in sensitization of respiratory mucosa. Re-exposure leads to the release of inflammatory mediators such as histamine. A late response, around 6-8 hours post-exposure leads to the release of interleukin-8, RANTES (regulated on activation of normal T cells expressed and secreted) and Eotaxin. This results in eosinophil chemotaxis.
The first stage
of the allergic response is characterized by symptoms such as nasal congestion, sneezing, coughing, sore throat
. The late response is accompanied by obstruction of the nasal passage as well as non-specific hyper-responsiveness. Chronic rhinitis has also been associated with extensive fungi growth.
Allergic inflammation in the lower respiratory airway may lead to new onset asthma, or exacerbation of existing asthma in sensitized patients. Heavy mold exposure has also been shown to trigger lower respiratory illnesses in infants. Inflammatory response may manifest itself in symptoms such as chest tightness, shortness of breath and bronchospasm. Some 10 per cent of the general population is estimated to have IgE antibodies, with as many as have of them attributable to sensitization by fungal allergens.
4.3.3 Hypersensitivity Pneumonitis and Interstitial Lung Disease
Hypersensitivity pneumonitis, also known as extrinsic allergic alveolitis
, is a disease brought on by exposure to organic dust from fungi
. Sensitization and recurrence require prolonged, high-intensity exposure to the fungal allergens that can activate cellular (Gell and Combs type III and IV) hypersensitivity. Mold exposure is associated with many forms of the disease, including what is commonly known as farmer™s lung along with other less prevalent forms of the disease. It is often found in occupational settings, or amongst avian hobbyists. Hypersensitivity pneumonitis is an unreported disease, which makes it even harder to estimate its prevalence and incidence.
In addition to hypersensitivity pneumonitis, exposure to aerosolized mold antigens has also been linked to the prevalence of interstitial lung disease
. This disease is also reported in higher incidence in occupations such as farming, carpentry and metal working. This disease is found in two forms: usual interstitial pneumonitis (UIP) and idiopathic pulmonary fibrosis (IPF). It is yet to be established whether interstitial lung disease is only an advanced form of hypersensitivity pneumonitis or a separate antigenic response altogether.
4.3.4 Allergic Bronchopulmonary Aspergillosis and Allergic Fungal Sinusitis
Allergic Bronchopulmonary Aspergillosis (ABPA) and Allergic Fungal Sinusitis (AFS) are intense immunologic responses to fungi. ABPA usually affects existing asthma or cystic fibrosis patients when there is Aspergillus growth in their airway, leading to eventual sensitization and hypersensitivity to this species of fungi
. While the presence of fungi aggravates the hypersensitivity reaction, ABPA is brought on by a more significant anatomical change in the lung. ABPA patients complain of exacerbated asthma and eosinophilic pneumonia. The early stages of ABPA are characterized by peripheral eosinophilia and circulation of IgE and IgG antibodies to Aspergillus.
This is usually followed by central bronchiectasis in later stages. Aggravation of the hypersensitivity reaction is controlled by administering oral steroid and itraconazole therapy.
Allergic Fungal Sinusitis (AFS) is characterized by fungal growth in sinuses which causes an immunologic response to antigens
. This usually leads to high production of mucin, and often leads to destruction of adjacent tissue material. AFS may be managed through surgery, immunotherapy and steroid-based immune suppression. Initially attributed to Aspergillus fumigatus
exclusively, a number of mitosporic fungi species are now recognized as common causative agents. While these symptoms are noted only in a small number of patients with environmental mold-related diseases, early detection and treatment can help alleviate distress and progressive worsening of the hypersensitivity reaction.
It has also been proposed that exposure and sensitization to Alternaria fungi may be responsible for chronic rhinosinusitis
. While some evidence for altered immune response among such individuals has been noted, it is not sufficient to establish a causal relation between the two.
4.3.5 Meta-analysis of Respiratory Effects
Fisk et al conducted a meta-analysis of the clinical data available on associations between respiratory health effects and mold-affected dwelling spaces.[ii]
The review made use of random effect models for comparison across studies across substantially different definition of symptoms, selected subjects and location. Odds ratios and 95% CIs (confidence intervals) were transformed to log scale. Subsequently, random effects models were applied to each specific outcome category.
Finally, an estimate was provided of percentage increases/decreases in outcomes through the following formula:
give the prevalence of the health outcomes in populations with and without risk to mold. Data from 33 studies met the above criteria. Central estimate of ORs were found to range between 1.34 and 1.74, while confidence levels (CI) exceeded 1.2. The figure below represents the odds ratios and confidence intervals with regard to wheeze studies that were included in the meta-analysis.
The major finding of the meta-analysis was that the estimated percentage increases in health outcomes in damp indoor environments was found to vary between 30 and 52 per cent
. In almost all instances, these associations were statistically significant. While simple correlation is not enough to prove a causal link between building dampness and illness, relatively strong associations can be made for dampness-related exposures. Damp environments are usually characterized by poor indoor air quality, and may carry a large variety of microorganisms. Dampness, without doubt, increases the subject™s risk of exposure to these fungal and bacterial agents, which may then manifest itself in higher incidence of mold-related illnesses among occupants.
The key results for various health outcomes, along with the number of studies included in each, is given in the table below.
4.4 Skin Allergies and Infections
Allergic dermatitis has also been associated with exposure to mold. A wide range of allergic dermatologic reactions to mold are observed, including dryness, excessive itching
. Studies by Maes et al. and Maibach have provided evidence that prolonged and high-intensity exposure to mold through contact may trigger immunologically mediated dermatitis.[iii]
Some fungi are known to be highly pathogenic
, and can cause serious illnesses in individuals. While they are usually associated with the occupational activities described above, damp conditions may accelerate their growth. Histoplasma capsulatum
is found in bat guano and bird droppings. Causative agent of histoplasmosis, it leads to cause interstitial or cavitary pneumonia. Cryptococcus
, found in pigeon droppings, typically causes localized infections but may lead to meningoencephalitis or cavitating pneumonia in immuno-compromised individuals. It has been associated with exposure to pigeon droppings on windowsills or air conditioning units in urban office buildings. Sporotrichosis
fungi, usually found in gardening soil, lodge themselves in cuts, pricks and lesions. They cause cutaneous or lymphangitic lesions.
Minor skin-based fungal infections
are common even among healthy individuals. They are usually sporadic and can be easily cured. Dermatophytes such as Tinea cruris
, and pedis
cause infections on skin, hair or nails. These superficial fungal infections may be more prevalent in some environments. Tinea pedis
, for instance, may easily be contracted through use of damp public spaces like changing rooms at swimming pools and gymnasiums, where it is exceedingly common.
4.5 Immunological Dysfunction
There is little credible evidence to show that mold spores or components may be causative agents in any form of immune dysfunction.
There is no clinically significant evidence
to support the hypothesis that fungi may be responsible for any form of immunodeficiency. Even studies amongst workers with heavy and prolonged exposure to mold have not found symptoms of immunodeficiency such as opportunistic infections. While drugs such as Cyclosporine are based on the immunosuppressive properties of fungi, such concentrations cannot be found in the environment. Studies attempting to prove a link between fungi and autoimmune diseases in humans have likewise failed to provide any conclusive evidence to support their case.
At the same time, subjects with compromised immunological response should ideally be kept away from moldy environments where they may be exposed to fungal infection. For instance, the exposure of patients with lowered immunity due to ongoing or recent chemotherapy must also be restricted
. For the same reason, children with cystic fibrosis should be kept away from damp spaces with prevalence of Aspergillus
, while AIDS patients may be restricted from buildings with pollutants from heavy pigeon droppings.
4.6 Ingested Toxins
Spoiled or contaminated foods often contain high levels of mycotoxins that are produced as secondary metabolites during cell reactions in fungi. Ingestion of these chemicals in large doses is toxic for humans. Consumption of mycotoxins in quantities in excess of one milligram per kilogram of body weight is likely to cause violent illness.
While the exposure levels for the immunological and allergic effects of mold vary across a wide range, the dose ranges for ingested mycotoxins can be defined more clearly. Consequently, government regulations regarding safe levels of selected mycotoxins such as aflatoxin
are in place. While aflatoxin is found in peanut-based products, ocratoxin is found in grain products and wine. In addition to their effects when ingested, these mycotoxins are also an occupational hazard to agricultural/warehouse workers exposed to them in aerosolized form.
While most research has tended to concentrate on the direct ingestion of mycotoxins through spoiled food, it is also argued that inhaled mycotoxins are also absorbed into the body primarily through the digestive tract. It is conjectured that the ingestion of small doses of mycotoxins through the digestive tract may be connected to instances of headache, sinus problems, attention
deficit and so on.These association, however, are yet to be supported by convincing evidence. This is partly because most research on mycotoxin toxicity has been carried out for purposes of animal husbandry, with a focus on disorders such as fertility.
4.7.1 Organic Dust Toxic Syndrome (ODTS)
ODTS is a general term that refers to an illness with general flu-like symptoms
with pronounced respiratory difficulty. These symptoms appear without warning some hours after a heavy, prolonged exposure to dust containing organic material. With symptoms similar to hypersensitivity pneumonitis, ODTS is differentiated as not being mediated through immunological mechanisms. Unlike other hypersensitivity reactions, ODTS is triggered by a single exposure
. It has been extensively documented in both indoor as well as outdoor occupational settings where persons are heavily exposed to fungal growth.
4.7.2 Pulmonary Hemorrhage in Infants
Placing infants in damp and moldy environments puts them at risk of pulmonary hemorrhage. Receiving intense interest in recent years, the exact causes of this syndrome continue to elude researchers. There is, however, adequate evidence to suggest that infants be removed from moldy environments as a precautionary measure.
4.7.3 Neurotoxic Effects
Reports such as Baldo et al. have also drawn attention to the possibility of neurotoxicity following mold exposure.[iv]
While definitive conclusions are not possible given the current state of research in the field, a number of illuminative case studies point towards an association between the two. The investigated health effects include memory loss, changes in personality and difficulties in concentrating.
4.8 The Hygiene Hypothesis
The hygiene hypothesis postulates that subjects brought up in a highly sanitized environment are at a higher risk of developing allergies. The correlation
between crowded, unhygienic living conditions in early life and lower occurrence of diseases
such as eczema, hay fever and hepatitis A has been substantially supported with cross-sectional studies.
In the last few years a number of rigorous studies have shown the protective effects of controlled exposure to fungi. One such study in 2006 showed strongly protective association between Penicillium
fungi and asthma.[v]
According to another, higher endotoxin exposure has been correlated with a decreased risk in developing atopic sensitivity and asthma. A research group reported in 2007 that β-glucan components were protective against chronic wheezing among infants.[vi]
The results, nonetheless, are inconsistent. A trial found that heavy exposure to Cladosporium
decreased susceptibility to fungal sensitization, but led to higher risks of bronchial hyperresponsiveness. In another instance, while exposure to Penicillium
fungi increased the risk of atopy in infants, Cladosporium
was found to have the inverse effect.
Given the available data on the phenomenon, the protective effect of fungal exposure remains unverified
. While in some instances, mild exposure to specific fungal agents may have some protective effects against allergies, results are too varied and contradictory to allow generalization.
5. Environment Assessment
Exposure can be defined as an event that causes people to come in contact with a pollutant at a particular concentration over a specific duration of time.[vii]
While this may provide an ideal definition, it is usually not possible to accurately determine levels of such exposure. Consequently, most assessment is carried out with the help of exposure indicators. Data on such indicators must usually be gathered either through questionnaire-based interviews
or qualitative walk-through assessments
by experienced professionals. Both these approaches have their relative advantages. While systematic professional assessments provides somewhat standardized procedures, interviewing dwelling occupants and affected patients gives a better understanding of temporal variations in the aggravation of symptoms. Finally, while some methods such as air and culture sampling are available, they are highly variable in their results and suffer from a number of others limitations.
5.1 Mold and Occupational Spaces
Be it home or the place of work, extended exposure to moldy environments can precipitate allergic and toxicological reactions in individuals. Given rising concerns about occupational health amongst employers, employees and regulatory bodies, the phenomenon of mold is receiving renewed attention. Over the last few years, many studies have generated a growing body of evidence related to occupational illnesses amongst school teachers working in spaces with identified mold-related problems. The Center for Indoor Environments and Health at the University of Connecticut Health Center has presented a number of case studies that illuminate the adverse effects of occupational environments on office workers and school teachers in particular.[viii]
In the absence of adequate quantified research on the causal connections between molds and human health,
these case studies are helpful in arriving at a qualitative understanding of the complex relationship between indoor mold exposure, diagnosis and possible remedial strategies.
In one of the cases published by the Center, a 57-year-old career school teacher suffering from adult-onset asthma
was advised to move out of the environment for a few months. Within 60 days, her physical examination showed normal results. Returning to the school, which had a known history of poor air quality, she once again complained of symptoms such as metallic taste, cough, fatigue and skin rashes. She was diagnosed with hypersensitivity pneumonitis and moved out of her place of work. This again resulted in a resolution of the symptoms.
In another case, two teachers at a rural school suffering from water intrusion and mold growth were diagnosed with sarcoidosis
and occupational asthma
. The first teacher reported symptoms over a three-year period, recurring only during the school year. An assessment of the teacher™s working environment and the temporal cycles of the symptomal eruptions, her physician declared hers to be a sentinel case and offered spirometric testing to others at the school experiencing similar symptoms. Another teacher at the school was in the process diagnosed with occupational asthma. Tests showed a 19.8 per cent decline in FVC (Forced Vital Capacity) and 12.3 per cent in FEVI (Forced Expiratory Volume) Both patients reported that their symptoms were somewhat alleviated when they were outside the school building.
In a third instance, a 42-year-old office worker developed symptoms such as breathing difficulties, heavy sneezing and rash
that could be temporally associated with renovation work in her office building for mold intrusion. Despite repeated changes in her seating location in the office, she continued to be exposed to mold and experienced worsening of symptoms.
5.2 The Thumb-rule of Health Risk from Mold
While only systematic assessment of an environment can determine the concentration and amount of fungi-related allergens, toxins and cell fragments in the air, experts generally recommend a cautious approach to dampness and mold in indoor spaces. As a thumb rule, the US Environmental Protection Agency advises that all molds have the potential to cause health effects.[ix]
Further, an indoor environment may be considered susceptible if it is proved that it is damp. While most individuals do not exhibit hypersensitivity or toxicological reactions to indoor mold, the wide range of various variables means that some individuals may indeed show such responses. For this reason, self-reporting based on these indicators are limited in their usability for diagnosis and research as they may introduce errors in cross-sectional studies with both allergic as well as non-allergic participants.
5.3 Systematic Environmental Assessment
The proper assessment of mold-related problems in indoor spaces draws on a wide range of field of expertise, including knowledge of building design and construction, an understanding of bioaerosols, and a focus on the health-related effects of indoor air quality. Personnel such as industrial hygienists, indoor environmental quality consultants and environmental health professionals are generally equipped with the range of expertise required for mold assessment. At the same time, a specific focus on bioaerosols
must be considered an essential qualification for anyone carrying out such assessments.
5.4 Qualitative Environmental Assessment
A qualitative assessment attempts to identify conditions that support mold formation and possible pathways of intrusion, and suggests corrective measures that are attuned to the specific needs and limitations of a given indoor space. Such an assessment attempts to locate possible areas of mold amplification.
The assessor collects information by two means: first, by interviewing the occupants of the building; and second, by undertaking a walk-through assessment of the location
. The walk-through assessment will make note of possible fungi growth in the immediate outdoor environment, seepage or leaks within the building, surface condensation, visible mildew, and areas with moldy smells. The Guidance for Clinicians on the Recognition and Management of Health Effects Related to Mold Exposure and Moisture Indoors
lays out a minimal checklist that must be covered in any environmental assessment. It is recommended that the assessor look at the following:
- A visual assessment of the exterior of the building. This must include sources of mold like old leaf piles; damage to the outside of the building that may allow water intrusion; bird droppings near ventilation intakes; and evidence of stagnant water.
- An assessment of the heating, ventilation and air-conditioning (HVAC) system. This would include looking for dirt and/or microbial growth in the air filters and cooling and heating coils; accumulated water in drain pans, etc; and cleanliness of ducting. The quality of air indoors is determined to a great extent by airflow and ventilation characteristics.
- A survey of the occupied spaces in the building. Particular attention must be paid to indoor water damage; condensation on window frames and sills; dust and dampness on carpet and upholstery; maintenance of humidifiers and air-conditioners.
A detailed and perceptive assessment of an indoor environment can go a long way in determining possible aggravating factors for patients. A professional assessor will also be able to put in place a course of remediation that is tailored to the specific requirements of the building in question.
Bodies such as the American Conference of Governmental Industrial Hygienists (ACGIH)[x]
provide detailed protocols for mold sampling as part of environmental assessments. Assessors use a combination of source sampling
and air sampling
to obtain a clearer picture of the specific varieties of mold being encountered. Sampling at source may take the form of lifting samples for microscopic assessment, or bulk sampling of dust or collected materials. A number of sampling methods based on the principle of mass spectroscopy have been used to study the level of mycotoxins in samples with heavy fungal growth. Such approaches are also compromised by the inability to register very low toxin concentrations. Moreover, the presence of mycotoxins as such does not necessarily imply exposure to their effects. Given below in tabular form are the various methods of sampling and analysis available to environmental assessors.
5.6 Limitations of Environmental Sampling
The extreme variability of factors affecting the presence of mold spores in indoor air has meant that most environmental and health agencies have refrained from establishing set numerical limits for levels of mold concentration. Usually dependent on methods such as volumetric sampling, such analysis can only be carried out for discrete locations for a very short duration of about 1-8 minutes. At best, one may draw more comprehensive conclusion through a comparative study of multiple indoor and outdoor samples. This too must be undertaken with caveats. For instance, while the detection of higher mold concentrations indoors is usually taken as a sign of mold amplification, even common xerophillic fungi such as Aspergillus
sometimes show such a variation even on normal days. Consequently, air sampling is unable to account for spatial and temporal variations in the aerosolization of spores
. Moreover, even an accurate measure of mold concentration in air is of limited utility, since the appearance of symptoms also depends to a great extent on the specific hypersensitivity of specific individuals.
Specific testing methods have been developed for a limited number of microbial agents, while procedures for others such as fungal (1→3)-β-D-glucans or fungal extracellular polysaccharides are yet to be scientifically validated and commercially viable.
In addition to these methodological problems, bioaerosol samples in particular pose practical difficulties in storage and transportation
. This may introduce error in the analysis of substances such as endotoxins, which are affected by such activity.
5.7 Other Mold Detection Methods
It has been suggested that scanning a visibly affected area with ultraviolet (UV) light
may help detect the presence of some mold-related toxins that exhibit fluorescence under such conditions. A technique that has found widespread use particularly in testing of agricultural produce, it may also find some utility in indoor spaces. It may not be adequate to trace all kinds of mold toxins, but to its advantage, this method is cheap, quick and quite effective with respect to particular strains of mold toxins. The table below lists some common mold toxins that fluoresce under UV light, along with their molecular weights and effective radiation wavelengths.
6. Mold Remediation and Removal
The clean-up of mold-damaged environments is a time-consuming process, and must be undertaken in a rigorous and manner. For a successful clean-up, two aspects of the process of mold exposure must be taken into account. On the one had, one needs to address issues of dampness and humidity, which exacerbates the growth of fungi indoors. On the other hand, care must be taken to address existing mold growth which must be removed to prevent recurrent amplification.
6.1 Three Steps to Mold Remediation
Given the hardiness of mold spores and the inherent complexity of the clean-up process, a systematic three-stage procedure is recommended for thorough remediation.
- The first step is to identify and control sources of water damage in the building structure. This would include repair of leakages in the building waterworks as well as the ducting and condenser areas of the heating system. Steam leaks must also be remedied, since the high humidity generated can promote proliferation of fungal growth. One must also control the incursion of water into the building through leaks and seepage in walls, floors, basement areas and so on. Given below are two tables with estimated costs associated with controlling moisture in new as well as existing buildings.
- The second step is to ensure conditions of low relative humidity in the dwelling/working spaces. This may be maintained with the aid of ventilation and humidity control systems. While the relative humidity must be kept at a level below 60 per cent, an optimum level of 30-50 per cent is recommended for highly sensitized individuals. This is because humidity levels of 50 per cent or more absorption of moisture by hydroscopic dust may create suitable conditions of growth for many dust mites and fungi varieties. The graph below represents a psychometric chart of relations between air temperature, absolute humidity (water in grams per kilogram of dry air) and relative humidity in the air.
- The third step comprises of removal and disposal of water-damaged materials. This would include removal of materials such as porous construction material, paneling, tiles, as well as household objects such as carpeting, books and mattresses. Any object that has been wet or damp for extended periods of time may harbor growths of mold.
In cases of serious water damage due to flooding, etc. it is highly recommended that one take the assistance of professional cleaning experts with the requisite experience and expertise.
Ventilation is of critical importance in improving indoor air quality in damp spaces. It allows the dilution and removal of airborne mold spores and fragments, and the control of temperature and humidity conditions that allow mold amplification. As a general thumb rule, building occupants as well as health care providers are advised to achieve a rate of ventilation sufficient to replace or substantially dilute the concentration of airborne spores
. The imprecision and at times, inability to measure levels of various fungal components and byproducts has rendered any attempt at standardization futile.
Changes to the ventilation system of a building, however, must be taken up cautiously. On the one hand, changes in airflow through the building envelope may cause damage to the exterior structure. On the other, changes in pressure gradients may affect the movement of fungal pollutants in and out of the building.
In hot climates, the ventilation system is often augmented with air conditioning and humidity control systems. These complicate the work of mold remediation in many ways. The equipment itself may become a receptacle of mold growth
for instance, air conditioning ducts or humidifier drip pans. Moreover, humidifiers may create conditions of high humidity, while air-conditioned spaces may show signs of sick-building syndrome. In a review of literature on indoor air quality, a 2009 World Health Organization report states that ventilation rates greater than 10 liters/second per person are known to significantly reduce sick-building syndrome and increase work performance and productivity.[xi]
It is possible to use both natural as well as mechanical methods to improve ventilation. Natural ventilation
depends on the use of windows, shafts, etc. to draw in fresh air into the building without the use of any mechanical devices. While this is a highly cost-effective alternative, it is suitable only for mild to moderate climates
. It is also impractical to naturally ventilate large and deep buildings. Wind towers, stack systems and atrium ventilation, however, are often integrated into building structure with favorable results. Mechanical ventilation
includes exhaust ventilation or the more elaborate supply and exhaust ventilation. Mechanical ventilation systems are particularly useful in that they allow a constant ventilation rate irrespective of indoor conditions. These systems also allow a degree of control of pressure differences across the building envelope, which can help prevent dampness-related damage to building exteriors. Mechanical ventilation systems can also be easily integrated with heating and cooling systems. When fitted with air filtration systems, they can also purify the outdoor air being supplied to the occupants of the building. These systems also have their own disadvantages. Their installation may sometimes require extensive renovation
of existing buildings. In addition, the extensive ventilation and air conditioning equipment itself may become a host for mold if not maintained on a regular basis.
6.3 Cleaning Mold-affected Household Objects
Mold growths on objects may be either active or dormant. In conditions where humidity conditions become unsuitable, fungi become dormant, no longer producing spores or consuming substrate material. Should the humidity rise again, however, these mold spores will again become active with renewed growth. Consequently, while active mold must be treated immediately, dormant mold can be left undisturbed indefinitely, as long as environmental factors are controlled with low humidity and temperature levels. Treatment of dormant fungi is relatively easy the mold becomes dry and powdery, and can simply be dusted off with a brush. Brushing and dusting
, however, may lead to the dispersal of mold spores in the environment or their becoming deeply lodged into the substrate. Consequently, vacuuming
is the recommended method of removal, particularly in cases of relatively minor outbreaks.
Active mold must be approached with care, as attempts to dust it off will only smear the surface and securely embed the mold into the material. Active mold can usually be identified through simple chemical-based tests that give quick and accurate results. Lactophenol-cotton blue solution is known to stain living tissue. When treated with lactophenol-cotton blue solution, a fungus sample will be stained blue if it contains any active mycelia or spores.
Mold intrusion may be treated through either fungicidal or fungistatic methods. Fungicidal agents
such as ethylene oxide kill mold and mold spores effectively. Extensive mold damage may require the intervention of professionals who can administer more specialized treatment procedures. Fungistatic materials
, such as thymol and ortho phenyl phenol, arrest mold growth by inactivating it. Fungistatic chemicals, however, do not completely kill molds. Extended use of some fungicidal and fungistatic agents, however, may produce toxic byproducts or cause damage to substrate materials
. The latter can be a serious concern when removing mold from objects that may have artistic or antique value, with an ever-present risk of material damage or staining.
Chemical treatments offer no residual protection, since mold can be expected to return if the underlying factors of dampness are not addressed. So much so, killing even 99 per cent of a mold colony is virtually insignificant hundred of thousands of spores can be regenerated from a single spore. In the light of this, the traditional approach of focusing on the killing of mold is inherently limited. Moreover, chemicals that are strong enough to kill 99 per cent or more of mold are known to have adverse toxic effects on humans. Thus controlled temperature, relative humidity and ventilation remain the best measures against indoor mold
6.4 Risks of Chemical Clean-up
Studies in the last two decades have proved conclusively that:
- First, all biocides are capable of chemically reacting with the substrate materials they are used on
- Second, all biocides show some level of toxicity for mammals, which makes them potentially harmful for those administering these chemicals, as well as those exposed to the environment in which they are used.
Chemicals are usually administered in two ways: through either fumigation
or topical application
. While fumigation is aimed at altering the environment in which the mold is growing, topical application looks to disrupt the fungi™s chemical reactions.
Chemicals widely in use today for fumigation purposes show varying levels of toxicity. Often used in large spaces such as libraries and museums through the 1970s, ethylene oxide
was shown by Ballard and Baer[xii]
to be highly toxic for humans and is subject to strict regulations from the 1980s. Widespread studies showed that ethylene oxide was a carcinogenic, mutagenic, genotoxic, reproductive, neurologic, and sensitization hazard.
and ortho phenyl phenol
are widely used as fumigants. These chemicals are moderately toxic when inhaled or ingested. Levels of safe exposure for these chemicals have not yet been established, as adequate data is not available.
Most organo-metal-based fumigants, however, are being progressively banned in a number of countries. A number of alternatives, based on plant derivatives are becoming commercially available and more viable.
6.5 Protective Care during Clean-up
Two aspects of mold removal operations must be anticipated and prepared for in advance. These are: first, the release of the cleaned spores back into the environment; and second, exposure of sensitized individuals during the clean-up process.
Patients may at times need to undertake minor cleaning or disposal of mold-affected objects. In such cases, care must be taken to use appropriate protective gear
for the eyes as well as exposed skin surfaces. In addition, patients with breathing-related difficulties are advised to use a fitted respirator with N95 filters. For heavier cleaning, it is usually recommended that the patients seek help from a non-sensitized individual. Cleaning of household objects must be done either outdoors or in a closed room that can be thoroughly cleaned afterwards. A fume hood may also be used to prevent spores from spreading out in the environment. Vacuum cleaners are particularly effective in removing mold. One must, however, be cautious about exhausting the spores back into the environment
. To prevent this, the vacuum cleaner ought to be fitted with a high efficiency particulate air filter.
Work in water-damaged buildings, such as demolition, renovation and routine maintenance also exposes both workers as well as the surrounding environment in general to possibly allergic or toxic mold spores and fragments. Building occupants are usually protected through practices such as segregation of the construction area, reducing dust and redirection of airflow. Workers in jobs with higher exposure such as air conditioning maintenance are also provided specific instructions according to their trades by unions and associations.
7. Patient Care
The wide gaps in our knowledge about the relation between mold and human illness notwithstanding, the physician must approach the possibility of mold-induced disease in a systematic manner. Given below is an algorithm that medical practitioners may use to diagnose and treat fungal diseases caused due to damp environments.
To establish a relation between specific symptoms in the patient and damp environment, a healthcare provider must
- Categorize the symptoms, define the patho-physiology of the patient, and arrive at a diagnosis
- Through interviews, questionnaires, etc determine the possibility of mold amplification and exposure
- Draw connections between such exposure and the patient™s symptoms
There are broadly three categories of patients who consult physicians about mold-related health problems. In the first group, there are those with specific conditions that are recurrently aggravated by environmental factors including moisture and dust. In the second category may be placed patients with less-specific signs and symptoms that nonetheless seem to have specific seasonal and spatial patterns, or are associated with particular activities. Finally, in a third residual category we may place those patients with no clear symptoms but apprehensive about mold exposure. Each of these categories requires a tailor-made use of available diagnostic tools and assessment methods for optimal efficacy.
Given below is a concise algorithm for practitioners to follow in handling all three types of cases. The following sections will take up patient care procedures for each of these categories in detail.
7.1 Patients with Recurrent Environment-induced Symptoms
Medical conditions such as hypersensitivity pneumonitis, new or aggravated asthma, sarcoidosis, interstitial lung disease and pulmonary hemorrhage in infants have been associated with heavy and long-term exposure to mold. If left undetected or untreated, they may lead to progressive deterioration of the disease, or even death. Even in the absence of clear diagnosis of one of the above illnesses, an enquiry into environmental factors is warranted in patients who report mucosal irritation recurrent rhinitis/sinusitis and hoarseness of voice
. Precautions at an early stage help limit their exposure and prevent progression of illness. This information is presented in graphic form in Table A.
For patients already diagnosed with one of the above diseases, practitioners may use the questions in Table C to carry out a preliminary assessment of environmental exposure.
7.2 Patients with Symptoms Specific to Place and Time
Symptoms such as headache, mild breathing difficulty, dizziness, skin rashes and so on are extremely common and cannot be exclusively associated in the first instance with mold
. Patients may be asked the questions given in Table B to identify whether these commonplace symptoms are possibly associated with environmental factors of dampness and mold. Should the patient report a relationship between symptoms and humid conditions, they should be asked the questions in Table C. Should the answer to questions related to moisture be negative, mold may safely be ruled out as a possible cause.
7.3 Patients with Exposure Concerns
With growing awareness about the effects of poor air quality and mold exposure, a number of patients with general symptoms but serious worries may ask for medical advice. The detailed questionnaire in Table D will help the medical care provider to ascertain whether the patient™s symptoms demonstrate any temporal, spatial or seasonal patterns.
7.4 Clinical Evaluation
A diagnosis of asthma or hypersensitivity pneumonitis may be verified with spirometry with lung function and diffusion capacity tests. Metacholine- and histamine-based challenge testing may be used in cases where spirometry shows inconclusive results for reversible bronchospasm. Chest radiographs and lung biopsies may be used to identify hypersensitivity pneumonitis.
Available tests for immune response, organ functioning, allergic responses may be useful, but are not disease-specific. IgE antibody counts may be useful as indicators of atopic individuals.
7.5 Environment-specific Clinical Evaluation
A careful combination of clinical evaluation and environmental assessment
may provide a more productive approach as compared to exclusive use of either approach. Physicians may conduct a targeted clinical evaluation of the patient before and after an exposure. Once an assessment of the patient™s environment has offered a preliminary indication of a specific place of sustained mold exposure, clinical tests may be helpful in ascertaining if dwelling or occupational spaces are aggravating the patient™s condition. In cases of hypersensitivity pneumonitis or advanced asthma, the patient may take a long time to show clear signs of improvement. Such factors obviously need to be accounted for and modified on a patient-to-patient basis.
7.6 Medical Treatment
Recommended treatment may be pursued for conditions such as asthma or hypersensitivity pneumonitis. In the more severe cases, the patient should be advised to move out of the offending environment since prolonged exposure in such cases causes irreversible damage. Allergic reactions due to mold exposure may be treated the same way as other allergies. Antihistamines and corticosteroids may be administered. Given the difficulty in measuring the presence of mold related agents and fragments, it is often impossible to determine whether there has been any improvement in the space to allow a reintroduction of the patient. The only alternative available is to bring the individual back to the environment under careful monitoring with adequate post-exposure testing.
The use of medication in treating mold-related symptoms must, however, be adopted cautiously. Often, removal from and remediation of the problematic environment is not given as much importance as medication. Removal from the environment is particularly important when the illness is chronic and progressive
. But suppression of symptoms without removal of the specific agent in question from the patient™s environment may only lead to greater morbidity and aggravated relapse.