Dynamics of airborne fungal populations in a large office building

Mold in Paradise: A Review of Fungi Found in Libraries

Libraries contain a large amount of organic material, frequently stored with inadequate climate control; thus, mold growth represents a considerable threat to library buildings and their contents. In this essay, we review published papers that have isolated microscopic fungi from library books, shelving, walls, and other surfaces, as well as from air samples within library buildings. Our literature search found 54 published studies about mold in libraries, 53 of which identified fungi to genus and/or species. In 28 of the 53 studies, Aspergillus was the single most common genus isolated from libraries. Most of these studies used traditional culture and microscopic methods for identifying the fungi. Mold damage to books and archival holdings causes biodeterioration of valuable educational and cultural resources. Exposure to molds may also be correlated with negative health effects in both patrons and librarians, so there are legitimate concerns about the dangers of contact with high levels of fungal contamination. Microbiologists are frequently called upon to help librarians after flooding and other events that bring water into library settings. This review can help guide microbiologists to choose appropriate protocols for the isolation and identification of mold in libraries and be a resource for librarians who are not usually trained in building science to manage the threat molds can pose to library holdings.

Airborne bacterial and PM characterization in intensive care units: correlations with physical control parameters

In this study, the spatial variation of airborne bacteria in intensive care units (ICUs) was characterized. Fine particulate matter and several physical parameters were also monitored including temperature and relative humidity. The results showed that the total bacterial load ranged between 20.4 and 134.3 CFU/m³ across the ICUs. Bacterial cultures of the collected samples did not isolate any multi-drug-resistant Gram-negative bacilli indicating the absence of such aerosolized pathogens in the ICUs. Meanwhile, particulate matter levels in several ICUs were found to exceed the international guidelines set for 24-h PM exposure. Moreover, examining bacterial load contribution by size suggested that bacteria with sizes less than 0.65 µm contributed the least to the total bacterial loads, while those with sizes between 0.65 and 1.1 µm contributed the most. A multiple linear regression model was also built to predict the bacterial loads in the ICUs. The regression analysis explained 77% of the variability observed in the measured bacterial concentrations. The model showed that the level of activity in the ICU rooms as well as its occupancy level had strong positive correlations with bacterial loads, while distance away from the patient had a non-linear relationship with measured loads. No statistically significant correlation was found between bacterial load and particulate matter concentrations.

Field sampling of indoor bioaerosols

Because bioaerosols are related to adverse health effects in exposed humans and indoor environments represent a unique framework of exposure, concerns about indoor bioaerosols have risen over recent years. One of the major issues in indoor bioaerosol research is the lack of standardization in the methodology, from air sampling strategies and sample treatment to the analytical methods applied. The main characteristics to consider in the choice of indoor sampling methods for bioaerosols are the sampler performance, the representativeness of the sampling, and the concordance with the analytical methods to be used. The selection of bioaerosol collection methods is directly dependent on the analytical methods, which are chosen to answer specific questions raised while designing a study for exposure assessment. In this review, the authors present current practices in the analytical methods and the sampling strategies, with specificity for each type of microbe (fungi, bacteria, archaea and viruses). In addition, common problems and errors to be avoided are discussed. Based on this work, recommendations are made for future efforts towards the development of viable bioaerosol samplers, standards for bioaerosol exposure limits, and making association studies to optimize the use of the big data provided by high-throughput sequencing methods.

Identifying indoor air Penicillium species: a challenge for allergic patients

PURPOSE

Penicillium is the most common mould isolated in housing. Penicillium chrysogenum is the only species tested by prick test or serology for allergic patients. The American Institute of Medicine has accepted Penicillium as an aetiological agent of rhinitis in children and adults and as an asthma agent in children. However, few studies have identified Penicillium in housing to the species level (354 species). Phenotypic identification is difficult. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) should be an alternative. The aim of this study was (1) to identify the Penicillium species present in dwellings in Eastern France and (2) to evaluate the reliability of MALDI-TOF MS for identification, by comparing it to DNA sequencing and phenotypic identification.

METHODOLOGY

Identification to the species level was performed by MALDI-TOF MS on 275 strains isolated from 48 dwellings. These results were compared to beta-tubulin gene sequencing and to the phenotypic aspects.

RESULTS

Thanks to MALDI-TOF, 235/275 strains could be identified (85.5 %). Fourteen species were identified among 23 Penicillium species included in the Filamentous Fungi Library 1.0 (Bruker Daltonics). However, 72.2  % of the strains belonged to five main taxa: P. chrysogenum (27.3 %), Penicillium glabrum (22.9 %), Penicilliumcommune (11.3 %), Penicillium brevicompactum (6.5 %) and Penicillium expansum (4.2 %).

CONCLUSION

Complete coherence between MALDI-TOF MS and sequence-based identification was found for P. chrysogenum, P. expansum, P. glabrum, Penicillium italicum and Penicillium corylophilum. The main drawback was observed for Penicillium crustosum, which included 21 strains (7.6 %) that could not be identified using MALDI-TOF MS.

Quantification of mold contamination in multi-level buildings using the Environmental Relative Moldiness Index

The goal of this study was to evaluate the possible use of the Environmental Relative Moldiness Index (ERMI) to quantify mold contamination in multi-level, office buildings. Settled-dust samples were collected in multi-level, office buildings and the ERMI value for each sample determined. In the first study, a comparison was made between two identical four-story buildings. There were health complaints in one building but none in the other building. In the second study, mold contamination was evaluated on levels 6-19 of an office building with a history of water problems and health complaints. In the first study, the average ERMI value in the building with health complaints was 5.33 which was significantly greater than the average ERMI value, 0.55, in the non-complaint building. In the second study, the average ERMI values ranged from a low of -0.58 on level 8 to a high of 5.66 on level 17, one of the top five ranked levels for medical symptoms or medication use. The mold populations of ten (six Group 1 and four Group 2) of the 36-ERMI molds were in significantly greater concentrations in the higher compared to lower ERMI environments. The ERMI metric may be useful in the quantification of water-damage and mold growth in multi-level buildings.

Seasonality in airborne bacterial, fungal, and (1→3)-β-D-glucan concentrations in two indoor laboratory animal rooms

AIMS

The purpose of this study was to assess the temporal changes in the concentrations of bioaerosols in a laboratory mouse room (LMR) and laboratory rabbit room (LRR), and to determine environmental factors associated with the culturable bacteria, fungi and (1→3)-β-D-glucan concentrations.

METHOD

The concentrations of culturable airborne bacteria, fungi and (1→3)-β-D-glucan in the LMR and LRR were sampled once a month from March 2011 to February 2012. A single-stage viable cascade impactor was used to sample bacteria and fungi, while a two-stage cyclone bioaerosol sampler was used to collect airborne (1→3)-β-D-glucan.

RESULTS

The culturable bacterial concentrations in the LMR showed a gradual increase during the summer. The culturable fungal concentrations showed similar seasonal patterns of change in the LMR and LRR with a noticeable increase during the summer. The (1→3)-β-D-glucan concentrations were highest during the warmer spring and summer months. Relative humidity (RH) was the environmental factor most associated with the concentrations of culturable bacteria and fungi. The overall airborne microbe concentrations were significantly higher in the LRR than in the LMR.

CONCLUSIONS

Airborne microbe concentrations in the LMR and LRR varied greatly depending on season, and these changes were affected by environmental factors.

The theory and application of space microbiology: China's experiences in space experiments and beyond

Microorganisms exhibit high adaptability to extreme environments of outer space via phenotypic and genetic changes. These changes may affect astronauts in the space environment as well as on Earth because mutant microbes will inevitably return with the spacecraft. However, the role and significance of these phenotypic changes and the underlying mechanisms are important unresolved questions in the field of space biology. By reviewing, especially the Chinese studies, we propose a space microbial molecular effect theory, that is, the space environment affects the nature of genes and the molecular structure of microorganisms to produce phenotypic changes. In this review, we discussed three basic theories for the research of space microbiology, including (1) space microbial pathogenicity and virulence mutations and the human mutualism theory; (2) space microbial drug-resistance mutations and metabolism associated with space pharmaceuticals theory; (3) space corrosion, microbial decontamination, and new materials technology theory.

Procedures to Assist Health Care Providers to Determine When Home Assessments for Potential Mold Exposure Are Warranted

Drawing evidence from epidemiology and exposure assessment studies and recommendations from expert practice, we describe a process to guide health care providers helping their patients who present with symptoms that might be associated with living in damp housing. We present the procedures in the form of a guided 2-part interview. The first part has 5 questions that triage the patient toward a more detailed questionnaire that reflects features of housing conditions known to be reliably associated with exposures to mold and dampness contaminants. We chose the questions based on the conditions associated with moisture problems in homes across the United States and Canada. The goal is to facilitate the clinician's effort to help patients reduce exposure to environmental triggers that elicit symptoms to better manage their disease.

Seasonal variation in airborne endotoxin levels in indoor environments with different micro-environmental factors in Seoul, South Korea

This study evaluated the variation over a year in airborne endotoxin levels in the indoor environment of five university laboratories in Seoul, South Korea, and examined the micro-environmental factors that influenced endotoxin levels. These included temperature, relative humidity, CO2, CO, illumination, and wind velocity. A total of 174 air samples were collected and analyzed using the kinetic limulus amebocyte lysate assay. Endotoxin levels ranged from <0.001 to 8.90EU/m(3), with an overall geometric mean of 0.240EU/m(3). Endotoxin levels showed significantly negative correlation with temperature (r=-0.529, p<0.001), CO2 (r=-0.213, p<0.001) and illumination (r=-0.538, p<0.001). Endotoxin levels tended to be higher in winter. Endotoxin levels in laboratories with rabbits were significantly higher than those of laboratories with mice. Multivariate regression analysis showed that the environmental factors affecting endotoxin levels were temperature (coefficient=-0.388, p<0.001) and illumination (coefficient=-0.370, p<0.001). Strategies aimed at reducing airborne endotoxin levels in the indoor environments may be most effective if they focus on illumination.

Indoor fungi: companions and contaminants

This review discusses the role of fungi and fungal products in indoor environments, especially as agents of human exposure. Fungi are present everywhere, and knowledge for indoor environments is extensive on their occurrence and ecology, concentrations, and determinants. Problems of dampness and mold have dominated the discussion on indoor fungi. However, the role of fungi in human health is still not well understood. In this review, we take a look back to integrate what cultivation-based research has taught us alongside more recent work with cultivation-independent techniques. We attempt to summarize what is known today and to point out where more data is needed for risk assessment associated with indoor fungal exposures. New data have demonstrated qualitative and quantitative richness of fungal material inside and outside buildings. Research on mycotoxins shows that just as microbes are everywhere in our indoor environments, so too are their metabolic products. Assessment of fungal exposures is notoriously challenging due to the numerous factors that contribute to the variation of fungal concentrations in indoor environments. We also may have to acknowledge and incorporate into our understanding the complexity of interactions between multiple biological agents in assessing their effects on human health and well-being.

Detection and identification of xerophilic fungi in Belgian chocolate confectionery factories

Chocolate confectionery fillings are generally regarded as microbiologically stable. The stability of these fillings is largely due to the general practice of adding either alcohol or preservatives. Consumer demands are now stimulating producers to move away from adding alcohol or other preservatives to their confectionery fillings and instead to search for innovative formulations. Such changes in composition can influence the shelf life of the product and may lead to spoilage by xerophilic fungi. The aim of this study was to test whether the production environment of Belgian chocolate confectionery factories and common ingredients of chocolate confectioneries could be potential sources of contamination with xerophilic fungal species. In the factory environment, the general and strictly xerophilic fungal spore load was determined using an RCS Air Sampler device in combination with DG18 and MY50G medium, respectively. Four basic ingredients of chocolate confectionery fillings were also examined for fungal spore levels using a direct plating technique. Detected fungi were identified to species level by a combination of morphological characterization and sequence analysis. Results indicated a general fungal spore load in the range of 50-250 colony forming units per cubic meter of air (CFU/m(3) air) and a more strict xerophilic spore load below 50 CFU/m(3) air. These results indicate rather low levels of fungal spores present in the factory environment. The most prevalent fungi in the factory environment were identified as Penicillium spp., particularly Penicillium brevicompactum. Examination of the basic ingredients of confectionery fillings revealed nuts to be the most likely potential source of direct contamination. In nuts, the most prevalent fungal species identified were Eurotium, particularly Eurotium repens.

Microbial existence in controlled habitats and their resistance to space conditions

The National Research Council (NRC) has recently recognized the International Space Station (ISS) as uniquely suitable for furthering the study of microbial species in closed habitats. Answering the NRC’s call for the study, in particular, of uncommon microbial species in the ISS, and/or of those that have significantly increased or decreased in number, space microbiologists have begun capitalizing on the maturity, speed, and cost-effectiveness of molecular/genomic microbiological technologies to elucidate changes in microbial populations in the ISS and other closed habitats. Since investigators can only collect samples infrequently from the ISS itself due to logistical reasons, Earth analogs, such as spacecraft-assembly clean rooms, are used and extensively characterized for the presence of microbes. Microbiologists identify the predominant, problematic, and extremophilic microbial species in these closed habitats and use the ISS as a testbed to study their resistance to extreme extraterrestrial environmental conditions. Investigators monitor the microbes exposed to the real space conditions in order to track their genomic changes in response to the selective pressures present in outer space (external to the ISS) and the spaceflight (in the interior of the ISS). In this review, we discussed the presence of microbes in space research-related closed habitats and the resistance of some microbial species to the extreme environmental conditions of space.

Determinants, reproducibility, and seasonal variation of ergosterol levels in house dust

This study aimed to clarify the determinants that affect the concentrations of ergosterol and viable fungi in house dust and to examine the seasonal variation and reproducibility of ergosterol concentrations indoors. In studying the determinants, dust samples from living room floors and vacuum cleaner dust bags were collected from 107 farming and 105 non-farming homes. Ergosterol levels were determined with gas chromatography-mass spectrometry,and the dust bag dust was cultivated for enumeration of fungal genera. Lifestyle and environmental factors, for example using of the fireplace, and visible mold observations in homes, explained 20–26% of the variation of fungal concentrations. For the reproducibility study, samples were collected from five urban homes in four different seasons. The reproducibility of ergosterol determinations within a sample was excellent (ICC = 89.8) for floor dust and moderate (ICC = 63.8) for dust bag dust, but poor when sampling the same home throughout a year (ICC = 31.3 and 12.6, respectively) due to large temporal variation in ergosterol concentrations. In conclusion, environmental characteristics only partially predicted the variation of fungal concentrations. Based on these studies, we recommend repeated sampling of dust over time if one seeks to adequately describe overall fungal levels and exposure in a home.

PRACTICAL IMPLICATIONS

This study shows that levels of ergosterol and viable fungi in house dust are related to visible mold observations. Only 20% of the variation in fungal levels can be explained with questionnaires, and therefore, environmental samples need to be taken in addition. Reproducibility of ergosterol determination was excellent for floor dust, and thus, ergosterol measurements from floor dust samples could be suitable for assessing the fungal load in building investigations. The temporal variation needs to be taken into account when describing the ergosterol concentration of urban homes.

International Space Station environmental microbiome - microbial inventories of ISS filter debris

Despite an expanding array of molecular approaches for detecting microorganisms in a given sample, rapid and robust means of assessing the differential viability of the microbial cells, as a function of phylogenetic lineage, remain elusive. A propidium monoazide (PMA) treatment coupled with downstream quantitative polymerase chain reaction (qPCR) and pyrosequencing analyses was carried out to better understand the frequency, diversity, and distribution of viable microorganisms associated with debris collected from the crew quarters of the International Space Station (ISS). The cultured bacterial counts were more in the ISS samples than cultured fungal population. The rapid molecular analyses targeted to estimate viable population exhibited 5-fold increase in bacterial (qPCR-PMA assay) and 25-fold increase in microbial (adenosine triphosphate assay) burden than the cultured bacterial population. The ribosomal nucleic acid-based identification of cultivated strains revealed the presence of only four to eight bacterial species in the ISS samples, however, the viable bacterial diversity detected by the PMA-pyrosequencing method was far more diverse (12 to 23 bacterial taxa) with the majority consisting of members of actinobacterial genera (Propionibacterium, Corynebacterium) and Staphylococcus. Sample fractions not treated with PMA (inclusive of both live and dead cells) yielded a great abundance of highly diverse bacterial (94 to 118 taxa) and fungal lineages (41 taxa). Even though deep sequencing capability of the molecular analysis widened the understanding about the microbial diversity, the cultivation assay also proved to be essential since some of the spore-forming microorganisms were detected only by the culture-based method. Presented here are the findings of the first comprehensive effort to assess the viability of microbial cells associated with ISS surfaces, and correlate differential viability with phylogenetic affiliation.

Fungal rhinosinusitis: what every allergist should know

The interaction between fungi and the sinonasal tract results in a diverse range of diseases with an equally broad spectrum of clinical severity. The classification of these interactions has become complex, and this review seeks to rationalize and simplify the approach to fungal diseases of the nose and paranasal sinuses. These conditions may be discussed under two major headings: non-invasive disease (localized fungal colonization, fungal ball and allergic fungal rhinosinusitis) and invasive disease (acute invasive rhinosinusitis, chronic invasive rhinosinusitis and granulomatous invasive rhinosinusitis). A diagnosis of fungal rhinosinusitis is established by combining findings on history, clinical examination, laboratory testing, imaging and histopathology. The immunocompetence of the patient is of great importance, as invasive fungal rhinosinusitis is uncommon in immunocompetent patients. With the exception of localized fungal colonization, treatment of all forms of fungal rhinosinusitis relies heavily on surgery. Systemic antifungal agents are a fundamental component in the treatment of invasive forms, but are not indicated for the treatment of the non-invasive forms. Antifungal drugs may have a role as adjuvant therapy in allergic fungal rhinosinusitis, but evidence is poor to support recommendations. Randomized controlled trials need to be performed to confirm the benefit of immunotherapy in the treatment of allergic fungal rhinosinusitis. In this article, we will summarize the current literature, addressing the controversies regarding the diagnosis and management of fungal rhinosinusitis, and focussing on those aspects which are important for clinical immunologists and allergists.

Microbial communities adhering to the obverse and reverse sides of an oil painting on canvas: identification and evaluation of their biodegradative potential

In this study, we investigated and compared the microbial communities adhering to the obverse and the reverse sides of an oil painting on canvas exhibiting signs of biodeterioration. Samples showing no visible damage were investigated as controls. Air samples were also analysed, in order to investigate the presence of airborne microorganisms suspended in the indoor atmosphere. The diversity of the cultivable microorganisms adhering to the surface was analysed by molecular techniques, such as RAPD analysis and gene sequencing. DGGE fingerprints derived from DNA directly extracted from canvas material in combination with clone libraries and sequencing were used to evaluate the non-cultivable fraction of the microbial communities associated with the material. By using culture-dependent methods, most of the bacterial strains were found to be common airborne, spore-forming microorganisms and belonged to the phyla Actinobacteria and Firmicutes, whereas culture-independent techniques identified sequenced clones affiliated with members of the phyla Actinobacteria and Proteobacteria. The diversity of fungi was shown to be much lower than that observed for bacteria, and only species of Penicillium spp. could be detected by cultivation techniques. The selected strategy revealed a higher microbial diversity on the obverse than on the reverse side of the painting and the near absence of actively growing microorganisms on areas showing no visible damage. Furthermore, enzymatic activity tests revealed that the most widespread activities involved in biodeterioration were esterase and esterase lipase among the isolated bacterial strains, and esterase and N-acetyl-β-glucosaminidase among fungi strains.

Assessment of microbiological indoor air quality in an Italian office building equipped with an HVAC system

The purpose of this study was to evaluate the level and composition of bacteria and fungi in the indoor air of an Italian office building equipped with a heating, ventilation and air conditioning (HVAC) system. Airborne bacteria and fungi were collected in three open-space offices during different seasons. The microbial levels in the outdoor air, supply air diffusers, fan coil air flow and air treatment unit humidification water tank were used to evaluate the influence of the HVAC system on indoor air quality (IAQ). A medium-low level of bacterial contamination (50-500 CFU/m(3)) was found in indoor air. Staphylococcus and Micrococcus were the most commonly found genera, probably due to human presence. A high fungal concentration was measured due to a flood that occurred during the winter. The indoor seasonal distribution of fungal genera was related to the fungal outdoor distribution. Significant seasonal and daily variation in airborne microorganisms was found, underlining a relationship with the frequency of HVAC system switching on/off. The results of this monitoring highlight the role of the HVAC system on IAQ and could be useful to better characterise bacterial and fungal population in the indoor air of office buildings.

The effect of environmental parameters on the survival of airborne infectious agents

The successful transmission of infection via the airborne route relies on several factors, including the survival of the airborne pathogen in the environment as it travels between susceptible hosts. This review summarizes the various environmental factors (particularly temperature and relative humidity) that may affect the airborne survival of viruses, bacteria and fungi, with the aim of highlighting specific aspects of environmental control that may eventually enhance the aerosol or airborne infection control of infectious disease transmission within hospitals.

The effect of environmental parameters on the survival of airborne infectious agents

The successful transmission of infection via the airborne route relies on several factors, including the survival of the airborne pathogen in the environment as it travels between susceptible hosts. This review summarizes the various environmental factors (particularly temperature and relative humidity) that may affect the airborne survival of viruses, bacteria and fungi, with the aim of highlighting specific aspects of environmental control that may eventually enhance the aerosol or airborne infection control of infectious disease transmission within hospitals.

Real-time PCR for detection of the Aspergillus genus

Aspergillus is a genus of mold that has strong indoor sources, including several species capable of acting as opportunistic pathogens. Previous studies suggest that Aspergillus could serve as an indicator for abnormal mold growth or moisture, making it an important genus for environmental monitoring. Here, a quantitative polymerase chain reaction (qPCR, or real-time PCR) assay is presented for Aspergillus. The assay shows good specificity for the genus, detecting all Aspergillus species tested, although a few non-Aspergillus species are also amplified. Sensitivity testing demonstrates that DNA representing one conidium can be detected. A validation study compared qPCR results against direct microscopy counts using A. fumigatus conidia aerosolized into a laboratory chamber. The assay was then used to quantify Aspergillus in indoor air samples, demonstrating its utility for environmental monitoring. Analysis of a small number of clinical sputum samples showed complete agreement with culturing results.

Microparticle sampling by electrowetting-actuated droplet sweeping

This paper describes a new microparticle sampler where particles can be efficiently swept from a solid surface and sampled into a liquid medium using moving droplets actuated by the electrowetting principle. We successfully demonstrate that super hydrophilic (2 microm and 7.9 microm diameter glass beads of about 14 degrees contact angle), intermediate hydrophilic (7.5 microm diameter polystyrene beads of about 70 degrees contact angle), and super hydrophobic (7.9 microm diameter Teflon-coated glass beads and 3 microm size PTFE particles of over 110 degrees contact angles) particles on a solid surface are picked up by electrowetting-actuated moving droplets. For the glass beads as well as the polystyrene beads, the sampling efficiencies are over 93%, in particular over 98% for the 7.9 microm glass beads. For the PTFE particles, however, the sampling efficiency is measured at around 70%, relatively lower than that of the glass and polystyrene beads. This is due mainly to the non-uniformity in particle size and the particle hydrophobicity. In this case, the collected particles staying (adsorbing) on the air-to-water interface hinder the droplet from advancing. This particle sampler requires an extremely small amount of liquid volume (about 500 nanoliters) and will thus be highly compatible and easily integrated with lab-on-a-chip systems for follow-up biological/chemical analyses.

Detection of aerosolized Alternaria alternata conidia, hyphae, and fragments by using a novel double-immunostaining technique

A double-immunostaining halogen immunoassay was developed to identify aerosolized conidia, hyphae, and fragments of Alternaria alternata by using an anti-Alternaria polyclonal antiserum, while, simultaneously, allergy to these components was concurrently determined by using human immunoglobulin E antibodies.

Changing microbial concentrations are associated with ventilation performance in Taiwan's air-conditioned office buildings

Our study conducted serial environmental measurements in 12 large office buildings with two different ventilation designs to obtain airborne microbial concentrations in typical office buildings, and to examine the effects of occupant density, ventilation type and air exchange efficiency on indoor microbial concentrations. Duplicate samples of airborne fungi and bacteria, a total of 2477 measurements, were collected based on a scheme of conducting sampling three times a day for at least seven consecutive days at every study building. Air change rates (ACHs) were also estimated by tracer gas concentration decay method, and measured by continuous Multi-Gas monitor for each building. Most sampling sites were with total fungal and bacteria concentrations higher than 1000 CFU/m(3), an often-quoted guideline in earlier research. Significantly higher concentrations of fungi and bacteria, as well as higher indoor/outdoor (I/O) ratios across most groups of airborne microbes, were identified in buildings with fan coil unit (FCU) system than those with air-handling unit (AHU) system (Student's t test, P < 0.0001). Older buildings and higher air exchange rates were statistically associated with greater indoor bacteria levels in FCU ventilated buildings (R(2) = 0.452); a pattern not found in AHU buildings. Increasing ACH seemed to be the determinant factor for rising indoor fungal and Cladosporium concentrations in those FCU buildings (R(2) = 0.346; 0.518). Our data indicated that FCU ventilated buildings might have provided more outdoor matters into indoor environments through direct penetration of outdoor air. Results also demonstrated a quantitative association between rising numbers of occupants and increasing indoor levels of yeast in both FCU and AHU ventilated buildings. The regression model identified in this study may be considered a reference value for proposing an optimal ACH, while with adequate filtration of fresh air, as an effective strategy in lowering indoor microbial concentrations in air-conditioned buildings.

PRACTICAL IMPLICATIONS

As control of indoor microbial contamination has become an increasing concern around the world, feasibility and effectiveness of adopting ventilation approach has attracted a significant interest. This field investigation demonstrated, quantitatively, critical variables to be taken into consideration while applying such a measure, including the kinds of microbes to be removed and the types of ventilation system already in place.

Isolation of wood-inhabiting fungi from Canadian hardwood logs

Wood-inhabiting fungi include many molds, wood-staining fungi, and decay fungi. Most of these fungal species can result in economic losses to wood users. Studies on molds, staining fungi, and decay fungi are necessary to be able to control their growth on wood and wood products. In this study, wood-inhabiting fungi were isolated from logs of 3 major Canadian hardwood species: sugar maple, white birch, and yellow birch. Two media were used for isolation. From these 3 wood species, a total of 1198 fungal cultures were obtained from summer- and winter-harvested logs in dry storage and under water sprinkling. The results showed that most fungal species were not host specific and affected all of the wood species tested. Frequently isolated molds were Alternaria alternata, Trichoderma species, and Mucor/Rhizopus (Zygomycota) species, frequently isolated staining fungi were Ophiostoma piceae and Ophiostoma piliferum, a frequently isolated bark saprophyte was Nectria cinnabarina, and frequently isolated decay fungi were taxa of the phylum Basidiomycota. More fungal species were isolated from summer-harvested logs than from winter-harvested logs. Fewer fungal cultures, especially decay fungi, were isolated from logs in early storage than from logs in late storage.Key words: molds, wood-staining fungi, decay fungi, fungal isolation, log storage.

Characterization of mold and moisture indicators in the home

As studies increasingly support the presence of health risks associated with mold and moisture, understanding fungal concentrations and physical measurements as they relate to the microenvironment becomes more important. We conducted a cross-sectional study in the homes of 64 subjects. The primary objective of this study was to use trained inspectors' list of indicators in rooms (bathroom, bedroom, and basement) and determine whether these indicators are associated with higher fungal levels or physical measurements. A new category for combining the concentrations of fungal species, referred to as moisture indicator fungi (MIF), is used in the analysis. Our results show that basements with a musty odor, efflorescence, water sources, or mold have a two- to threefold increase in fungal concentrations over basements without these indicators. The regression model for the basement was highly predictive of indoor MIF concentrations (r2 = .446, p = .017). Basement water sources are substantial predictors of indoor total fungi, MIF, and Aspergillus/Penicillium spp. MIF concentrations are higher in homes with basement water sources, and most notably, the increase in MIF concentrations is significant in other living spaces (bathroom and bedroom) of the dwelling. Basement water sources are important moisture/mold indicators for epidemiologists to use in exposure assessments performed in residential dwellings.

An update on pollen and fungal spore aerobiology

Changes in climate are altering pollen distribution. Predictive modeling can be used to forecast long- and short-term changes in pollen concentrations. Increasing evidence confirms the presence of pollen allergens on small, respirable particles in the air, explaining the occurrence of pollen-season increases in asthma. Like pollens, aboveground indoor fungal aerosols primarily reflect outdoor concentrations. Basement spore concentrations might be higher and reflective of local sources. Fungal presence in the indoor or outdoor air can be monitored on an area basis or with personal monitors. The samples can be analyzed by means of microscopy, culture, DNA probes, HPLC, or immunodetection. Total fungal biomass can be estimated on the basis of measurements of ergosterol or glucan in environmental samples. Unfortunately, there are no generally accepted standards for interpretation of fungal levels in indoor or outdoor air. At present, the best approach to indoor fungal control is moisture control in the indoor environment. This will essentially prevent fungal growth, except from extraordinary events.

Medical aspects of global warming

BACKGROUND

Global warming is caused by increased carbon dioxide (CO2)resulting in a greenhouse effect with enhanced warming of the earth. Measurements of CO2 show a steady increase over the past 30 years caused by the burning of fossil fuels and from the loss of natural CO2 sinks. A 100-year increase in global temperature by 0.3 to 0.6 degrees C is reflected in atmospheric warming, glacier shrinkage, and rising sea levels.

OBJECTIVES

Planetary ecosystem dynamics are being altered, challenging public health. It is predicted that morbidity and mortality will increase as a result of heat stress, as seen in recent heat waves in the U.S. Weather disaster effects will increase in number and magnitude, and both noninfectious and infectious diseases may flourish. A significant challenge will be the changes in life cycles of microbial species due to the warmer environs. Specific increases in incidence have been noted for vector-borne diseases, in addition to pulmonary findings, cardiovascular morbidity, neurological diseases, and occupational diseases.

CONCLUSIONS

Warming can be demonstrated by the observed changes that have already occurred in the environment, particularly the thinning of polar ice caps. The United States Global Research Program has been established to coordinate research activities, which responds to issues deemed important by the United Nations Framework Convention on Climate Change. Research issues pertain to the scientific uncertainties in the greenhouse effect, temperature measurements at various atmospheric levels and latitudes, and impact on biota redistribution. The Kyoto Protocol has mandated specific solutions, e.g., a 7% reduction in CO2 levels within 10 years. Future recommendations involve supporting new technologies that are available to decrease emissions as well as understanding the role that occupational and environmental specialists have in global warming recognition.