Fungal pollution of indoor environments and its management

Indoor environments play important roles in human health. The health hazards posed by polluted indoor environments include allergy, infections and toxicity. Life style changes have resulted in a shift from open air environments to air tight, energy efficient, environments, in which people spend a substantial portion of their time. Most indoor air pollution comes from the hazardous non biological agents and biological agents. Fungi are ubiquitous in distribution and are a serious threat to public health in indoor environments. In this communication, we have reviewed the current status on biotic indoor air pollution, role of fungi as biological contaminants and their impact on human health.     

Investigations on the surveys of office environments and the total evaluation method—IAQ-Index

1. 1. A comprehensive study was made to establish evaluation methods for better office environments.

2. 2. In our study, measurements of thermal, acoustic, lighting, airflow and air quality conditions in indoor environments were made as well as questionnaire to the occupants on the evaluations of indoor environments and the feeling of fatigue.

3. 3. We also made an attempt to rate the evaluation value based on concepts and standards to evaluate totally office environments in a view point of “the office environments where people can work healthy and vigorously”. The evaluation values were called IAQ-index.

Adjustments and adaptations to indoor and outdoor environments: Continuity and change in young adult rhesus monkeys

Optimal environments for captive primates are assumed to be those which simulate certain ecological features and elicit a wide range of species-typical behavior patterns. Outdoor environments are often thought to be more suitable than indoor environments in that they provide more space and potentially higher levels of stimulation. The purpose of this study was to compare the long-term behavioral responses of several groups of animals that had been reared identically during the first two years of life and then exposed to different environments. Two groups were moved into separate “enriched” indoor pens while one group was moved to an outdoor area covering approximately 5 acres. The monkeys were observed during the first year of life and again in these different environments between the ages of 6 and 10. Although behaviorally similar during the first year of life, monkeys developed different response patterns to indoor and outdoor environments. Contrary to commonly held views, indoor monkeys were not more aggressive, nor did they show higher levels of stereotypical behavior. Instead, indoor monkeys exhibited higher levels of grooming, sexual posturing, tactile/oral exploration, and passive visual behavior than their outdoor counterparts. These differences are consistent with the reconciliation model of de Waal. Individual monkeys also showed remarkable stability in certain traits over the 5-year period. © 1992 Wiley-Liss, Inc.     

An assessment of the air quality in indoor and outdoor air with reference to fungal spores and pollen grains in four working environments in Kerala, India

Qualitative and quantitative analyses of airborne fungal spores and pollen grains in four working environments (market, saw mill, poultry and cow sheds) in Thiruvananthapuram, the capital city of Kerala, India, were carried out for 2 years using Burkard Personal Slide Sampler and Andersen Two-Stage Sampler. Total spore concentration in these sites was always higher in indoor environments than in outdoor environments. Difference in concentration was not statistically significant in any of these work places except in saw mill (t test, p < 0.05). The highest spore concentration was recorded here followed by market, poultry and cow sheds. A total of 32 fungal spore types from indoor environments and 33 spore types from outdoor environments were recorded. Of them, 16 spore types were common to all the sites. Ameropsores, Cladosporium, other basidiospores, Ganoderma and Nigrospora were the dominant spore types in both indoor and outdoor environments. A total of 27 species of viable fungi from indoor and 24 species from outdoor environments were identified. Penicillium citrinum, Aspergillus flavus and Aspergillus niger were the most dominant viable fungi isolated. In contrast, total pollen concentration was always higher in outdoor environments than in indoor environments. Twenty-nine pollen types from indoor and 32 pollen types from outdoor were captured during the sampling. Poaceae, Cocos, Artocarpus, Amaranthus/Chenopodium and Tridax were the common and dominant pollen types observed in all the sites. Peak spore and pollen incidence were recorded during the late rainy and dry seasons (October–February) in both indoor and outdoor environments. The study revealed high prevalence of predominantly allergenic fungal spores and pollen grains in all the four work places. Workers/visitors are at potential risk of susceptibility to respiratory/allergic disorders.     

Diversity and seasonal dynamics of bacterial community in indoor environment

Background  

We spend most of our lives in indoor environments and are exposed to microbes present in these environments. Hence, knowledge about this exposure is important for understanding how it impacts on human health. However, the bacterial flora in indoor environments has been only fragmentarily explored and mostly using culture methods. The application of molecular methods previously utilised in other environments has resulted in a substantial increase in our awareness of microbial diversity.     

The airborne metagenome in an indoor urban environment

The indoor atmosphere is an ecological unit that impacts on public health. To investigate the composition of organisms in this space, we applied culture-independent approaches to microbes harvested from the air of two densely populated urban buildings, from which we analyzed 80 megabases genomic DNA sequence and 6000 16S rDNA clones. The air microbiota is primarily bacteria, including potential opportunistic pathogens commonly isolated from human-inhabited environments such as hospitals, but none of the data contain matches to virulent pathogens or bioterror agents. Comparison of air samples with each other and nearby environments suggested that the indoor air microbes are not random transients from surrounding outdoor environments, but rather originate from indoor niches. Sequence annotation by gene function revealed specific adaptive capabilities enriched in the air environment, including genes potentially involved in resistance to desiccation and oxidative damage. This baseline index of air microbiota will be valuable for improving designs of surveillance for natural or man-made release of virulent pathogens.     

Detection of Satratoxin G and H in Indoor Air from a Water-Damaged Building

The occurrence of Stachybotrys chartarum in indoor environments has been linked to adverse health effects as well as few cases of pulmonary haemorrhages in humans. Although the highly toxic secondary metabolites of this fungus, like satratoxin G and H, were frequently claimed with outbreaks of such diseases, these toxins have hardly been identified in the air of naturally contaminated indoor environments. Herein, a case of a LC-MS/MS-confirmed occurrence of airborne S. chartarum-toxins in a water-damaged dwelling is reported. Satratoxin G (0.25 ng/m(3)) and satratoxin H (0.43 ng/m(3)) were detected. This provides further evidence that Stachybotrys-toxins can be transferred from mouldy indoor materials into air, which could be a factor in the aetiology of health symptoms related to the sick building syndrome.     

Measurements of the effects of air quality on sensory perception

Occupants in indoor non-industrial environments decide whether the indoor air quality is acceptable or not. This paper describes the method by which the assessments of acceptability of air quality can be used to measure short-term sensory effects on humans caused by indoor exposures. Advantages and disadvantages of the method are discussed in the light of a need for future research in order to fully understand how many variables (environmental, organismic, physiological and psychological) influence the ratings of acceptability of air quality and to learn how the results obtained in laboratory experiments can be used to predict responses in natural environments.     

Mycotoxins as harmful indoor air contaminants

Fungal metabolites (mycotoxins) that pose a health hazard to humans and animals have long been known to be associated with mold-contaminated food and feed. In recent times, concerns have been raised about exposures to mycotoxin-producing fungi in indoor environments, e.g., damp homes and buildings. The principal mycotoxins that contaminate food and feed (alfatoxins, fumonisins, ochratoxin A, deoxynivalenol, zearalenone) are rarely if ever found in indoor environments, but their toxicological properties provide an insight into the difficulties of assessing the health effects of related mycotoxins produced by indoor molds. Although the Penicillium and Aspergillus genera of fungi are major contaminants of both food and feed products and damp buildings, the particular species and hence the array of mycotoxins are quite different in these environments. The mycotoxins of these indoor species and less common mycotoxins from Stachybotrys and Chaetomium fungi are discussed in terms of their health effects and the need for relevant biomarkers and long-term chronic exposure studies.     

Anthropogenic chemicals and their impacts on microbes living in buildings

Humans spend the vast majority of their time indoors where complex interactions occur among indoor anthropogenic chemicals, indoor microbiomes and human occupants. This paper summarizes previous work addressing interactions between anthropogenic chemicals associated with indoor household products and building materials, and microorganisms found within the built environment. Water availability seems to determine the extent to which microbes are impacted by anthropogenic chemicals, since desiccation remains one of the primary stressors regulating microbial viability indoors. Several lines of evidence suggest that both fungi and bacteria are capable of transforming biodegradable ingredients originating from various products used indoors when water is present. Previous research also establishes positive and significant correlations between anthropogenic chemicals that are antimicrobial and antibiotic resistance gene abundance. As researchers move towards understanding complex indoor environments as well as the role of anthropogenic chemicals in shaping microbiomes, in situ activities associated with the viable indoor microbial population merit more attention.     

Preliminary surveys of outdoor and indoor aeromycobiota in Uganda

This investigation was conducted during the period of March through June 1998 to trap, enumerate and identify the different airborne fungi in a variety of microhabitats of outdoor and indoor environments in different localities of Uganda. The settle plate method was used and Czapek-Dox agar was the isolation medium. A total of 47 genera and 61 species in addition to some other unidentified airborne fungi were trapped from all exposures at outdoor (39 genera and 52 species) and indoor (35 and 49) environments. The total fungal catches of outdoor airspora obtained from all exposures (and even in most individual exposures) were more than twice (5222 colonies) of that of the indoor ones (4361) when the exposure periods are taken into consideration. It is worth mentioning that the most highly polluted sites were either parks, forests or river banks for outdoor exposures, or teaching laboratory, library, laterines or bathrooms for indoor exposures. The most prevalent fungi from both outdoor and indoor microhabitats being species of Mycosphaerella, Yeasts, Penicillium, Fusarium, Aspergillus,Cochliobolus and Alternaria. However, several others were trapped frequently from either outdoor or indoor environments. On the other hand, several others were trapped only, but not frequently (in low or rare instances) from either outdoor or indoor microhabitats. The implications of these airborne spores are also discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Practices contributing to biotic pollution in Air-conditioned indoor environments

Indoor environments play important roles in human health. The health hazards posed by polluted indoor environments include allergy, infections and toxicity. The term ‘sick building syndrome’ (SBS) describes causes of building occupants experiencing adverse health effects that appear to be linked to the time spent in a building. Questionnaire-based data were collected from the people who live or work in air-conditioned (A/C) rooms. Responses of the occupants were analyzed to understand the practices contributing to biotic pollution of indoor air-conditioned environments. Our survey revealed some interesting facts about the users of A/C rooms and their practices that may be contributing to the indoor air quality. The allergy complaints and use of anti-allergy medicines were noted commonly among the occupants of government (Govt.) organizations and computer training centers where cleaning of room and A/C filters were not done periodically. Cleaning practices may reduce the complaints.     

Detection and identification of moulds in dutch houses and non-industrial working environments

The mycoflora of indoor non-industrial environments is reported from “case” studies in The Netherlands. Both air sampling by a RCS-Reutcr centrifugal air sampler and surface sampling by swabs and cellotape preparations were carried out in homes, archives and libraries, musea, offices and schools. Common species encountered in these indoor environments are Aspergillus versicolor, Penicillium brevicompactum, P. chrysogenum, Cladosporium spp. and the xerophilic fungi Eurotium spp. and Wallemia sebi. Aspergillus fumigatus, Scopulariopsis spp. and Stachybotrys chartarum were occasionally isolated. It is not always possible to detect the mycoflora growing on surfaces by air sampling. Therefore direct microscopical examination and sampling from surfaces in addition to air sampling is strongly recommended for the detection of viable moulds in indoor environments. Selection of the most suitable media for isolation of fungi is discussed.     

Removal of Viable Airborne Fungi from Indoor Environments by Benzalkonium Chloride-Based Aerosol Disinfectants

Fungi are ubiquitous in indoor environments, and some taxa can cause clinical symptoms in humans. Thus, from the viewpoint of public health, methods to reduce indoor airborne fungi are needed. The goal of this study was to examine the efficacies of benzalkonium chloride (BAC)–based aerosol disinfectants to remove airborne viable fungi from indoor environments. The laboratory- and field-based experiments were conducted to compare airborne culturable fungal concentrations before and after the disinfectant aerosol applications. The laboratory-based experiments showed the greater efficacies by the BAC-based disinfectant aerosol than by pure-water control aerosol (p <.05, t-test). In the field study using the BAC-based disinfectant aerosols, on average a 58% reduction of total airborne culturable fungal concentrations were observed. Additionally, the significant reduction was found for a group of airborne yeasts or yeast-like organisms (p <.05, Wilcoxon signed rank test). The BAC-based aerosol disinfectants are effective when used to reduce the numbers of airborne culturable fungi, in particular yeasts or yeast-like organisms, from indoor environments.     

Comparison of environmental tobacco smoke concentrations and mutagenicity for several indoor environments

Environmental tobacco smoke (ETS) is a major source for indoor air pollution. Although ETS-caused indoor air pollution has been well studied in the developed countries, few studies have examined ETS indoor air pollution in China, which currently has the largest population of tobacco smokers. In this study, respirable-particulate (RP) from ETS-contaminated (RP-ETS) indoor air was collected and measured in 5 different indoor environments during the winter in the northwestern Liaoning Province, China. The extractable portion of RP-ETS (ERP-ETS) was obtained by dichloromethane extraction and used in the Salmonella mutagenicity assay in the presence of S9 using strains TA98, TA100, and TA1538. The percentage of RP-ETS attributable to ETS (ETS-RP) and the percentage of ERP-ETS attributable to ETS (ETS-ERP) were estimated by measuring the concentration of solanesol, an ETS marker. Comparative results in 5 different indoor environments were: (1) the concentration of RP-ETS ranged from 197.3 to 1227.6 microg/m(3) and approximately 64.7 to 92. 0% of the RP-ETS originated from ETS; (2) the concentration of ERP-ETS ranged 88.8 to 601.5 microg/m(3) and approximately 83.1 to 95.4% of the ERP-ETS originated from ETS; (3) the mutagenic potency (revertants/m(3)) of ERP-ETS ranged from 60.4 to 595.5 for TA98, from 33.7 to 312.8 for TA100, and from 49.7 to 475.2 for TA1538. The data indicate that the extent of ETS pollution and the potential health hazards of ETS to humans in the five indoor environments are in the following increasing order: rural bedrooms, urban living rooms, office rooms, restaurants, and passenger cars in that area.     

Effects of temperature and humidity on the efficacy of methicillin-resistant Staphylococcus aureus challenged antimicrobial materials containing silver and copper

Aims:  To compare silver and copper, metals with known antimicrobial properties, by evaluating the effects of temperature and humidity on efficacy by challenging with methicillin resistant Staphylococcus aureus (MRSA) .
Methods and Results:  Using standard methodology described in a globally used Japanese Industrial Standard, JIS Z 2801, a silver ion-containing material exhibited >5 log reduction in MRSA viability after 24 h at >90% relative humidity (RH) at 20°C and 35°C but only a <0·3 log at ∼22% RH and 20°C and no reduction at ∼22% RH and 35°C. Copper alloys demonstrated >5 log reductions under all test conditions.
Conclusions:  While the high humidity (>90% RH) and high temperature (35°C) utilized in JIS Z 2801 produce measurable efficacy in a silver ion-containing material, it showed no significant response at lower temperature and humidity levels typical of indoor environments.
Significance and Impact of the Study:  The high efficacy levels displayed by the copper alloys, at temperature and humidity levels typical of indoor environments, compared to the low efficacy of the silver ion-containing material under the same conditions, favours the use of copper alloys as antimicrobial materials in indoor environments such as hospitals.     

Isolation of toxigenic Nocardiopsis strains from indoor environments and description of two new Nocardiopsis Species, N. exhalans sp. nov. and N. umidischolae sp. nov

Nocardiopsis strains were isolated from water-damaged indoor environments. Two strains (N. alba subsp. alba 704a and a strain representing a novel species, ES10.1) as well as strains of N. prasina, N. lucentensis, and N. tropica produced methanol-soluble toxins that paralyzed the motility of boar spermatozoa at <30 microg of crude extract (dry weight) x ml(-1). N. prasina, N. lucentensis, N. tropica, and strain ES10.1 caused cessation of motility by dissipating the mitochondrial membrane potential, Deltapsi, of the boar spermatozoa. Indoor strain 704a produced a substance that destroyed cell membrane barrier function and depleted the sperm cells of ATP. Indoor strain 64/93 was antagonistic towards Corynebacterium renale. Two indoor Nocardiopsis strains were xerotolerant, and all five utilized a wide range of substrates. This combined with the production of toxic substances suggests good survival and potential hazard to human health in water-damaged indoor environments. Two new species, Nocardiopsis exhalans sp. nov. (ES10.1T) and Nocardiopsis umidischolae sp. nov. (66/93T), are proposed based on morphology, chemotaxonomic and physiological characters, phylogenetic analysis, and DNA-DNA reassociations.     

Dry collection and culture methods for recovery of methicillin-susceptible and methicillin-resistant Staphylococcus aureus strains from indoor home environments

Staphylococcus aureus in home environments may serve as a reservoir for human colonization, making sampling of indoor surfaces relevant to exposure assessment. Using laboratory experiments and application to homes of asthmatic children in Barbados, we characterize microbiological methods adapted for settings with transportation delays between sampling and initiation of culture.     

Impact of indoor air pollution on health,comfort and productivity of the occupants

In this special report, the possible causes of indoor air pollution and its impact on the health, comfort and productivity of the building occupant are discussed. The causes and symptoms of sick building syndrome, allergy and environmental-illnesses and building related illnesses are discussed in the context of building environments. The remediation and prevention measures examine the solution to the problems caused by indoor air pollution in buildings     

Impact of indoor air pollution on health,comfort and productivity of the occupants

In this special report, the possible causes of indoor air pollution and its impact on the health, comfort and productivity of the building occupant are discussed. The causes and symptoms of sick building syndrome, allergy and environmental illnesses and building related illnesses are discussed in the context of building environments. The remediation and prevention measures examine the solution to the problems caused by indoor air pollution in buildings.