Impact of Fungal Spores on Asthma Prevalence and Hospitalization

Despite making up a significant proportion of airborne allergens, the relationship between fungal spores and asthma is not fully explored. Only 80 taxa of fungi have so far been observed to exacerbate respiratory presentations, with Cladosporium spp., Aspergillus spp., Penicillium spp., and Alternaria spp. found to comprise the predominant allergenic airborne spores. Fungal spores have been found in indoor environments, such as hospitals and housing due to poor ventilation. Meanwhile, outdoor fungal spores exhibit greater diversity, and higher abundance and have been associated with hospitalizations from acute asthma presentations. In addition, fungal spores may be the underlying, and perhaps the “missing link”, factor influencing the heightened rate of asthma presentations during epidemic thunderstorm asthma events. To improve our knowledge gap on fungal spores, airborne allergen monitoring must be improved to include not only dominant allergenic fungi but also provide real-time data to accurately and quickly warn the general public. Such data will help prevent future asthma exacerbations and thus save lives. In this review, we examine the health risks of prominent allergenic fungal taxa, the factors influencing spore dispersal and distribution, and why improvements should be made to current sampling methods for public health and wellbeing.     

Generation characteristics of fungal spore and fragment bioaerosols by airflow control over fungal cultures

We investigated the generation characteristics of airborne fungal fragments and spores by means of a newly developed fungal bioaerosol generation system that directs airflow to the fungal cultures horizontally. By controlling the airflow over the fungal cultures inside the generation system, we can produce three aerosolization modes of fungal bioaerosols: (i) fungal spores only, (ii) fungal fragments only, and (iii) a mixture of fragments and spores. As concerns over fungal fragments and spores have grown due to the adverse health effects of fungal bioaerosols, this generation study can be applied to develop techniques for controlling airborne fungal particles through means such as antifungal material tests, fungal bioaerosol filtering or sampling tests, and fungal bioaerosol inactivation tests. In addition, the generation system presented here simulates the environmental dispersal of fungal bioaerosols. Therefore, the results of this study can be interpreted as equivalent to the natural dispersal characteristics of fungal bioaerosols.     

Associations of Fungal Aerosols,Air Pollutants,and Meteorological Factors

The relationships between fungal aerosols and air pollutants meteorological factors were investigated in the Taipei urban area. In summer, it was observed that geometric mean (GM) concentrations of airborne fungal aerosols were 2,835 CFU m^-3 and 2,651 CFU m^-3 at Kuting and Hsichih stations, respectively. In winter, GM levels of airborne fungi were 1,107 CFU m I 3 and 2,248 CFU m^-3 at Kuting and Hsichih stations, respectively. Moreover, fungal aerosol concentrations were observed to highly depend on weather conditions, and the highest concentration of total colony counts appeared when the temperature was 25-30 C, the RH was 60-70% , and the wind speed was > 1 m s^-1 and from the S-SE wind direction. In addition, total fungal concentrations were negatively correlated with ozone concentrations, and concentration of Cladosporium spp. was positively correlated with hydrocarbons. PM₁₀ were positively correlated with Penicillium and the yeasts in Hsichih station. Our results demonstrated that airborne fungal aerosols are definitely correlated with air pollutants and meteoro logical factors. The complex dynamic interactions were indicated to occur among bioaerosols, air pollutants, and meteorological factors.     

Automated Spore Measurements Using Microscopy,Image Analysis,and Peak Recognition of Near-Monodisperse Aerosols

Rapid detection of airborne fungal and bacterial spores would enable public agencies to respond quickly and appropriately to intentional releases of hazardous aerosols. Automated analysis of microscope images and automated detection of near-monodisperse peaks in aerosol size distribution data offer complementary approaches to traditional methods for the identification and counting of fungal and bacterial spores. First, spores of the fungus Scopulariopsis brevicaulis were aerosolized in a chamber and then collected with a slit impactor; later, digital microscope images were analyzed manually to determine spore cluster distributions. The images also were analyzed with ImageJ, a program that automatically outlined objects and measured Feret's diameter, area, perimeter, and circularity. These characteristics were used to identify spore clusters automatically using two data analysis methods. Second, a computer program was developed to discriminate near-monodisperse bioaerosol peaks from those for polydisperse ambient particulate matter (PM) and was successfully tested using simulated and real aerosol mixtures. The observed agreement between manual and automated spore counts and the ability to detect spore peaks suggest that it may be possible to develop a system to recognize intentional releases rapidly through examination of particle morphology and size distributions. The peak detection procedure is potentially the fastest technique when used with real-time instrument data, but assumes that intentional releases would consist of large numbers of uniformly sized particles in the respirable size range.

Copyright 2012 American Association for Aerosol Research     

Temporal and Spatial Variation of Fungal Concentrations in Indoor Air

The aim of this study was to determine temporal and spatial variation of airborne concentrations of viable fungi in 2 single-family houses during the period of the year that such levels are mostly determined by indoor sources. One of the subject residences had moisture problems (the index residence), the other did not have any moisture problems (the reference residence). The concentrations of viable fungi in indoor air were determined a total of 6 times during the winter with 2 six-stage impactors (Andersen 10-800) in 2 rooms in both of the houses. The total concentrations of viable fungi and concentrations of Penicillium, Aspergillus, and Aspergillus versicolor     

Performance assessment of UVAPS: Influence of fungal spore age and air exposure

This work focused on two main outcomes. The first was the assessment of the response of the Ultraviolet Aerodynamic Particle Sizer Spectrometer (UVAPS) for two different fungal spore species. The UVAPS response was investigated as a function of fungal age and the frequency of air current that their colonies exposure to. This outcome was achieved through the measurement of fungal spore fluorescent percentage and fluorescent intensity throughout a period of culturing time (three weeks), and the study of their fluorescent percentage as a function of exposure to air currents. The second objective was to investigate the change of fungal spore size during this period, which may be of use as a co-factor in this differentiation. Fungal spores were released by blowing the surface of the culture colonies with continuous filtered flow air. The UVAPS was used to detect and measure auto-fluorescing biomolecules such as riboflavin and nicotinamide adenine dinucleotide phosphate (NAD(P)H) present in the released fungal spores.The study demonstrated an increase in aerodynamic diameter for fungal spores under investigation (Aspergillus niger and Penicillium species) over a period of time. The fluorescent percentage of spores was found to decrease for both fungal genera as they aged. It was also found that the fluorescent percentage for tested fungi decreased with frequency of air exposure. The results showed that, while the UVAPS could discriminate between Aspergillus and Penicillium species under well-controlled laboratory conditions, it is unlikely to be able to do so in the field.     

Design and evaluation of a new device for fungal spore aerosolization for laboratory applications

Fungi have significant health effects varying from serious allergic reactions from inhalation to toxic effects and even fatal infections. Indoor and outdoor sampling may identify potentially contaminated environments, but sampling techniques need refining to set risk levels regarding occupational exposure or to assess and analyse sudden outbreaks of fungi. As little is known of the sporulation and dispersal dynamics of fungi, we have experimented with aerosolizing fungal spores from cultures grown in standard 9 cm Petri dishes for 3–10 h using a new device that incorporates vibration. We evaluated the effect of the air flow and frequency on a quantity and pattern of spores aerosolized. Frequency had positive, negative or no effect. Positive quantitative effects were noted in Aspergillus versicolor at 50 Hz, in Aspergillus niger at 400 Hz and at 100–400 Hz in Rhizopus. Aerosolization of Aspergillus species dropped significantly in the first 20 min and then stabilised for 2.5–3 h. After this time period, the generation process became highly unstable with large quantities of small particles produced. It could be explained by appearance of cracks on the nutrient surface due to desiccation with corresponding release of particles of nutrient to the air carrier. For Rhizopus, the initial steep decrease in particle generation for the first 20 min of the process was followed by quite stable spore production for the following 10 h of process operation. There were no cracks observed on the nutrient surface for the entire 10 h operation of the device. The air flow also affects the efficiency of the spore release. It was found that increase in the air flow was associated with more efficient sporulation from the nutrient dish. On the other hand, the size distribution curve of the airborne spores produced at higher air flows was correspondingly slightly shifted towards larger sizes, which is related to less efficient loosening of spores and corresponding increase in concentration of clumps consisting of more than one spore. Also, it was found that incubation of fungal cultures for extended periods (2–6 weeks) led towards production of larger numbers of airborne fungal spores.     

Concentration and Size Distribution of Culturable Airborne Microorganisms in Outdoor Environments in Beijing,China

A one-year (from June 2003 to May 2004) study of airborne microbial concentration and size distribution was conducted systematically at three selected sampling sites in Beijing. Microbial samples were collected in triplicate for 3 min, 3 times per day, for 3 consecutive days of each month using FA-I sampler (imitated Andersen sampler, made by Applied Technical Institute of Liaoyang, China). Results showed that the concentration of total culturable microorganisms ranged from 4.8 × 10 ² colony forming units (CFU)/m ³ to 2.4 × 10 ⁴ CFU/m ³ , with an arithmetic mean of 3.7 × 10 ³ ± 2.1 × 10 ² (standard deviation) CFU/m ³ . As a whole, the percentage of airborne bacteria, accounting for 59.0% of the total culturable microorganisms, was significantly higher than those of airborne fungi (35.2%) and actinomycetes (5.8%). At RCEES (Research Center for Eco-Environmental Sciences—a culture and education area) and XZM (Xizhimen—a main traffic line), significantly higher percentages of airborne bacteria were found as compared to airborne fungi. No significant difference was observed between airborne bacteria and fungi at BBG (Beijing Botanical Garden—a green garden area). The total microbial concentration was significantly higher at RCEES than at XZM and BBG (*P < 0.05), and no significant difference between XZM and BBG was observed (P > 0.05). Total microbial concentrations were higher in summer and autumn, and lower in spring and winter at RCEES and XZM (*P < 0.05). At BBG, higher concentration was observed in summer during the sampling periods (***P < 0.001). The size distribution of airborne bacteria showed a skewed distribution at three sampling sites. The proportion of bacterial particles decreased gradually from Stage 1 ( > 7.0 μm) to Stage 6 (0.65 ～ 1.1 μm), and there was an obvious downtrend on Stage 2 (4.7 ～ 7.0 μm). Bacterial particles were mainly distributed at the first four Stages ( > 2.1 μm), accounting for 78.6% at RCEES, 84.0% at XZM, and 81.5% at BBG. The size distribution pattern of airborne fungi was found with normal logarithmic distribution at three sampling sites. Fungal particles were mainly distributed at Stage 3 (3.0 ～ 6.0 μ m), Stage 4 (2.0 ～ 3.5 μ m) and Stage 5 (1.0 ～ 2.0 μ m), composing 71.6% of the population at RCEES, 74.2% at XZM, and 68.3% at BBG. However, different distribution patterns were found in different dominant fungal genera. Cladosporium, Penicillium, and Aspergillus were present with normal logarithmic distribution, while Alternaria and sterile mycelia were found with skewed distribution. In opposition to the distribution pattern of fungal particles, the actinomycete particles at all sampling sites were primarily collected on Stage 1, Stage 5, and Stage 6, accounting for 61.1% at RCEES, 60.7% at XZM, and 64.8% at BBG.     

Fatty acids and polar lipid content of cheese and mould‐contaminated cheese

Unintended infestation of food with viable mould irreversibly leads to spoilage of food. However, little data existed on the fatty acid composition and polar lipid content of mould grown on cheese and the potential influence of these parameters in mould‐infested cheese. In this study, we thus focused on the fatty acids composition and polar lipid content of cheese, mould isolated from mould‐infested cheese, as well as inoculation of cheese with cultures of isolated moulds. For this purpose, we stored three cheese samples (gouda, brown cheese, and parmesan) over extended periods in order to force mould infestation from air. The moulds grown on gouda and brown cheese were identified as Penicillium brevicompactum and Penicillium roqueforti, respectively, while a mixed culture was obtained from parmesan. From these contaminated samples, mould spores were isolated and cultivated. Finally, the (pure) cheeses were inoculated with mould spores. Three subsamples, (1) cheeses, (2) moulds isolated from cheese, and (3) cheeses infested with the isolated moulds were studied with regards to their fatty acid distribution in the neutral and the polar lipids. The different amounts of polar lipids of cheese (0.39–2%), moulds (11–30.7%), and mould‐infested cheese (1.5–5%) allowed calculating the mould content of the mould‐infested cheeses.     

Fungal aerosols: A review

Fungal aerosols are important in the spread of plant, animal and human diseases. The development of this area of aerobiology is reviewed in relation to its influence on, and interaction with, the growth of aerosol science. Physical characteristics of airborne fungal spores relevant to their liberation, flight and deposition are discussed. Some samplers and sampling techniques especially suited to fungal aerosols are described.     

Dominant Mechanisms that Shape the Airborne Particle Size and Composition Distribution in Central California

The size and composition of ambient airborne particulate matter is reported for winter conditions at five locations in (or near) the San Joaquin Valley in central California. Two distinct types of airborne particles were identified based on diurnal patterns and size distribution similarity: hygroscopic sulfate/ammonium/nitrate particles and less hygroscopic particles composed of mostly organic carbon with smaller amounts of elemental carbon. Daytime PM₁₀ concentrations for sulfate/ammonium/nitrate particles were measured to be 10.1 μ g m^?3, 28.3 μ g m^?3, and 52.8 μ g m^?3 at Sacramento, Modesto and Bakersfield, California, respectively. Nighttime concentrations were 10–30% lower, suggesting that these particles are dominated by secondary production. Simulation of the data with a box model suggests that these particles were formed by the condensation of ammonia and nitric acid onto background or primary sulfate particles. These hygroscopic particles had a mass distribution peak in the accumulation mode (0.56–1.0 μ m) at all times. Daytime PM₁₀ carbon particle concentrations were measured to be 9.5 μ g m^?3, 15.1 μ g m^?3, and 16.2 μ g m^?3 at Sacramento, Modesto, and Bakersfield, respectively. Corresponding nighttime concentrations were 200–300% higher, suggesting that these particles are dominated by primary emissions. The peak in the carbon particle mass distribution varied between 0.2–1.0 μ m. Carbon particles emitted directly from combustion sources typically have a mass distribution peak diameter between 0.1–0.32 μ m. Box model calculations suggest that the formation of secondary organic aerosol is negligible under cool winter conditions, and that the observed shift in the carbon particle mass distribution results from coagulation in the heavily polluted concentrations experienced during the current study. The analysis suggests that carbon particles and sulfate/ammonium/nitrate particles exist separately in the atmosphere of the San Joaquin Valley until coagulation mixes them in the accumulation mode.     

Design and characterization of a fungal bioaerosol generator using multi-orifice air jets and a rotating substrate

Fungal bioaerosols, which are major constituents of ambient airborne microorganisms, are well known for their adverse health effects. However, thus far, the effective control of fungal bioaerosols has rarely been studied. A major reason for this is a lack of stable and reliable methods of generating fungal bioaerosols that can simulate real environmental dispersal. As a first step towards developing an efficient means of controlling fungal bioaerosols, we designed and evaluated a new fungal bioaerosol generator. The multi-orifice air jets and the rotating substrate inside the generator were used to uniformly scan a fungal culture Petri plate and to maintain uniformity of the production rate of fungal bioaerosols.We conducted the experimental tests on Aspergillus versicolor and Cladosporium cladosporioides. The particle size distribution and the total particle number concentration of generated fungal bioaerosols were measured using a particle size distribution analyzer and a condensation particle counter. The effects of the air flow rate and the rotating speed of the substrate on the generation of fungal bioaerosols were investigated. The results demonstrate that the fungal bioaerosol generator can produce mono-dispersed fungal bioaerosols under various experimental conditions and that it is possible to control the rates of production of fungal bioaerosols by adjusting the flow rate through the fungal generator and the rotating speed of the substrate.     

A New Filter Cassette for the Direct Microscopic Examination of Airborne Fungal Spores

The study describes a 25-mm filter cassette constructed with a plastic masking disk covering the bottom of the cassette cowl, reducing the area of exposed filter by 95%. Two rectangular sample traces, each with a size of 1.7 mm × 5.5 mm (9.35 mm²) were produced. The traces were sufficiently small to be analyzed by direct microscopic examination without requiring a sample transfer step. Direct microscopy of fungal spores using the new Bi-Air (BA) filter cassette was compared to the Air-O-Cell (AOC) slit impaction cassette using Penicillium chrysogenum and Stachybotrys chartarum spores. The comparisons involved the collection of side-by-side samples in a quiescent settling chamber.

The distribution of P. chrysogenum and S. chartarum spores between the duplicate BA sample traces was uniform. The deposition of spores across the sample traces was also similar for the BA and AOC, with a coefficient of variation (CV) between traverses of 27% for the BA and 29% for the AOC. The average retention of Penicillium spores was equivalent for mixed cellulose ester (MCE) filters with pore sizes of 1.2 um and 3 um. However, a 5 um pore size resulted in about a 20% reduction in the average retention for 3 um Penicillium spores. The average ratios of BA to AOC concentrations for P. chrysogenum spores were 2.0, 1.8, and 1.7 at airflow rates of 1 lpm, 2 lpm, and 3 lpm, respectively. The average ratio of BA to AOC concentrations for S. chartarum at the three airflow rates was 1.1.

The edges of the BA sample trace were well defined and bounded, and the sample area did not vary between samples. The constant size of the BA sample trace allowed less than 100% of the sample to be analyzed without affecting the precision of the analysis.     

Identification of single microbial particles using electro-dynamic balance assisted laser-induced breakdown and fluorescence spectroscopy

Online characterization of fungal and bacterial spores is important in various applications due to their health and climatic relevance. The aim of this study was to demonstrate the capability of the combination of electro-dynamic balance assisted laser-induced breakdown spectroscopy (LIBS) and laser-induced fluorescence (LIF) techniques for the online detection of single fungal spores (Aspergillus versicolor and Penicillium brevicompactum) and bacteria (Bacillus aureus). The method enabled sensitive and repeatable LIBS analysis of common elemental components (Ca, Na, and K) from single microbial particles for the first time. Significant differences in the concentrations of these elements were observed between the species, e.g., bacterial spores had over three orders of magnitude higher Ca concentration (2 × 10^?12 g/particle) compared to fungal spores (3–5 × 10^?16 g/particle). The LIF analysis has previously been used to distinguish bioaerosols from other aerosols due to their fluorescence ability. This study showed that combination of LIF and LIBS analysis is a promising tool for identification of different bioaerosol particle types.

Copyright © 2016 American Association for Aerosol Research     

Size reduction of Aspergillus versicolor fungal bioaerosols during a thermal heating process in continuous-flow system

Airborne fungi, termed fungal bioaerosols, have received attention due to their association with public health problems. The search for ways to prevent the harmful effects of fungal bioaerosols has created a high demand for research and development of efficient methods for controlling bioaerosols. We investigated variations in aerosol characteristics including total number concentration, size distribution, and surface morphology of fungal bioaerosols under a thermal heating process, a promising bioaerosol control method, in a continuous-flow system. Quantitative thermal characteristics of fungal bioaerosols were also obtained from thermogravimetric analysis. Our experimental results show that the aerodynamic and physical diameter of tested fungal bioaerosols decreased when exposed to increasing surrounding temperatures, even within a short exposure time of about 0.15 s. The instantaneous exposure to high temperature significantly changed the surface morphology of the fungal bioaerosols and caused thermal decomposition of the polymer component of the fungal cell wall. These variations in physical characteristics are closely related to the aerodynamic diameter of fungal bioaerosols.     

PERFORMANCE OF BIOAEROSOL SAMPLERS USED BY THE UK BIOTECHNOLOGY INDUSTRY

The quantitative assessment of bioaerosols is important in a number of industrial and health-care applications. Measurements to aid the control of airborne infection in hospitals, detection of the release of potentially harmful microorganisms from bio-processing equipment and monitoring the exposure of workers and animals to bioaerosols are examples of situations where different concentrations of microorganisms and varying ambient conditions may be expected. Microorganisms are notoriously difficult to assess accurately under such variable conditions and no single assay method is suitable for all applications; rather the method needs to be tailored to the application of interest. Problems are compounded by the differences in assay method (such as the type of media used for culturable counts) or sampler type selected, making the interpretation of the results difficult. An understanding of the airborne behaviour of microorganisms over a range of environmental conditions is vital if procedures are to be defined and recommended for the handling, sampling and assessment of bioaerosols. Microorganisms that are robust over a wide range of conditions are ideal as tracer particles. Unfortunately, the large majority of non-fungal bioaerosols are susceptible to damage. A predictable sampling procedure is required which will not affect the viability of the collected sample. Studies, reported on the development of procedures to characterise airborne biological particles, included tests carried out under controlled environmental conditions to compare the performance of five industrially important bioaerosol samplers with that of a reference glass wet-walled, cyclone sampler, using test aerosols of Saccharomyces cerevisiae cells and Penicillium expansum spores. The samplers tested were Andersen Microbial Sampler, Biotest RCS, Biotest RCS Plus, MicroBio MB1, and MicroBio MB2. The cyclone sampler, Andersen Microbial Sampler and the MicroBio MB1 and MB2 meet the basic criteria for a suitable reference sampler, except that the last three systems do not provide total counts. It will be important to investigate in the future how well they perform under the challenge of “real-life” conditions.     

Long-Term Sampling of Viable Airborne Viruses

A novel bioaerosol sampling technique, which utilizes the bubbling process in the collection fluid, has recently been developed and found feasible for a long-term personal sampling of airborne bacteria and fungal spores as it maintained high physical collection efficiency and high microbial recovery rate for robust and stress-sensitive microorganisms. Further tests have shown that the new technique also has potential to collect viable airborne viruses, particularly when utilized for a short-term sampling of robust strains. As the short-term sampling has a limited application for assessing personal exposure in bioaerosol-contaminated environments, the present study was undertaken to investigate the feasibility of the “bubbler” for a long-term monitoring of viable airborne viruses. Liquid droplets containing Vaccinia virions (that simulate Variola, a causative agent of smallpox) were aerosolized with a Collison nebulizer into a 400-liter test chamber, from which the droplets were collected by three identical prototype personal samplers in the liquid medium during different time periods ranging from 1 to 6 hours. The viral content was measured in the collection fluid of the sampler and in the initial suspension of the nebulizer using the fluorescence-based method and by enumerating plaque-forming units per milliliter of the fluids. The relative recovery of viruses after the sampling act was determined. The results show that the “bubbling” technique has consistent collection efficiency over time and is capable of maintaining the viability of Vaccinia, for at least 6 hours, with a loss in recovery rate of about 10%. The data demonstrate a good potential of the new technique for measuring personal exposure to robust airborne viruses over a long period.     

Deagglomeration testing of airborne nanoparticle agglomerates: Stability analysis under varied aerodynamic shear and relative humidity conditions

Occupational exposure to nanomaterial aerosols poses potential health risks to workers at nanotechnology workplaces. Understanding the mechanical stability of airborne nanoparticle agglomerates under varied mechanical forces and environmental conditions is important for estimating their emission potential and the released particle size distributions, which in consequence alters their transport and human uptake probability. In this study, two aerosolization and deagglomeration systems were used to investigate the potential for deagglomeration of nanopowder aerosols with different surface hydrophilicity under a range of shear forces and relative humidity conditions. Critical orifices were employed to subject airborne agglomerates to the shear forces induced by a pressure drop. Increasing applied pressure drop was found to be associated with decreased mean particle size and increased particle number concentrations. Rising humidity decreased the deagglomeration tendency as expressed by larger modal particle sizes and lower number concentrations compared to dry conditions. Hydrophilic aerosols exhibited higher sensitivities to changes in humidity than hydrophobic particles. However, the test systems themselves also differed in generated particle number concentrations and size distributions, which in turn altered the responses of created aerosols to humidity changes. The results of the present study clearly demonstrate that (a) humidity control is essential for dustiness and deagglomeration testing, (b) that (industrial) deagglomeration, for example, for preparation of aerosol suspensions, can be manipulated by subjecting airborne particles to external energies, and (c) that the humidity of workplace air may be relevant when assessing occupational exposure to nanomaterial aerosols.

Copyright © 2016 American Association for Aerosol Research     

Aerosol Concentrations During the 1999 Fresno Exposure Studies as Functions of Size,Season, and Meterology

Two 1999 Fresno exposure studies took place in February (winter season) and April/May (spring season) for periods of four weeks each. During that time, nearly continuous measurements of outdoor aerosol concentrations were made with a TSI Scanning Mobility Particle Sizer (SMPS) and a PMS optical particle counter (LASX). These instruments provide particle size distribution information from about 0.01 to 3     

Profile and Morphology of Fungal Aerosols Characterized by Field Emission Scanning Electron Microscopy (FESEM)

Fungal aerosols consist of spores and fragments with diverse array of morphologies; however, the size, shape, and origin of the constituents require further characterization. In this study, we characterize the profile of aerosols generated from Aspergillus fumigatus, A. versicolor, and Penicillium chrysogenum grown for 8 weeks on gypsum boards. Fungal particles were aerosolized at 12 and 20 L min^?1 using the Fungal Spore Source Strength Tester (FSSST) and the Stami particle generator (SPG). Collected particles were analyzed with field emission scanning electron microscopy (FESEM). We observed spore particle fraction consisting of single spores and spore aggregates in four size categories, and a fragment fraction that contained submicronic fragments and three size categories of larger fragments. Single spores dominated the aerosols from A. fumigatus (median: 53%), while the submicronic fragment fraction was the highest in the aerosols collected from A. versicolor (median: 34%) and P. chrysogenum (median: 31%). Morphological characteristics showed near spherical particles that were only single spores, oblong particles that comprise some spore aggregates and fragments (<3.5 μm), and fiber-like particles that regroup chained spore aggregates and fragments (>3.5 μm). Further, the near spherical particles dominated the aerosols from A. fumigatus (median: 53%), while oblong particles were dominant in the aerosols from A. versicolor (68%) and P. chrysogenum (55%). Fiber-like particles represented 21% and 24% of the aerosols from A. versicolor and P. chrysogenum, respectively. This study shows that fungal particles of various size, shape, and origin are aerosolized, and supports the need to include a broader range of particle types in fungal exposure assessment.