Personal size-separating impactor for sampling microbiological aerosols

A commercially-available personal impactor was altered to sample viable microorganisms onto a semisolid, moist, gelatin medium rather than onto a stainless steel or filter surface. The Marple personal cascade impactor is an eight-stage sampler with predicted cut-offs of 20, 15, 10, 6, 3.5, 2, 1, and 0.61 microns for stages one to eight, at a flow rate of 2 L/min. The possibility was examined that using trays containing a small amount of gelatin medium in place of the thin, flat filters of the original design would alter the impactor's performance. A polydisperse aerosol of di-2-ethylhexyl phthalate (DEHP or DOP) was sampled directly into an aerodynamic particle sizer and through a stage of the personal impactor. The aerosol particles penetrating the tested stage were sized and counted, and the counts compared with those in the total aerosol. With a Mylar medium filter as the collecting substrate, the measured particle cut-offs (D50) for stages four to seven were 5.2, 3.4, 1.4, and 1.0 microns. With a tray containing gelatin as the collecting substrate, the D50 were 5.9, 4.0, 1.6, and 1.0 microns. The size separation of the personal sampler for ambient bacterial and fungal aerosols compared well with that of the Andersen microbiological impactor. The use of a moist collecting surface, compared to a dry surface, can be expected to enhance recovery of viable airborne microorganisms sensitive to dehydration.     

Determining the spatial variability of personal sampler inlet locations

This article examines the spatial variability of dust concentrations within a coal miner's breathing zone and the impact of sampling location at the cap lamp, nose, and lapel. Tests were conducted in the National Institute for Safety and Health Pittsburgh Research Laboratory full-scale, continuous miner gallery using three prototype personal dust monitors (PDM). The dust masses detected by the PDMs were used to calculate the percentage difference of dust mass between the cap lamp and the nose and between the lapel and the nose. The calculated percentage differences of the masses ranged from plus 12% to minus 25%. Breathing zone tests were also conducted in four underground coal mines using the torso of a mannequin to simulate a miner. Coal mine dust was sampled with multi-cyclone sampling cans mounted directly in front of the mannequin near the cap lamp, nose, and lapel. These four coal mine tests found that the spatial variability of dust levels and imprecision of the current personal sampler is a greater influence than the sampler location within the breathing zone. However, a one-sample t-test of this data did find that the overall mean value of the cap lamp/nose ratio was not significantly different than 1 (p-value = 0.21). However, when applied to the overall mean value of the lapel/nose ratio there was a significant difference from 1 (p-value < .0001). This finding is important because the lapel has always been the sampling location for coal mine dust samples. But these results suggest that the cap location is slightly more indicative of what is breathed through the nose area.     

Comparison of coarse coal dust sampling techniques in a laboratory-simulated longwall section

Airborne coal dust generated during mining can deposit and accumulate on mine surfaces, presenting a dust explosion hazard. When assessing dust hazard mitigation strategies for airborne dust reduction, sampling is done in high-velocity ventilation air, which is used to purge the mining face and gallery tunnel. In this environment, the sampler inlet velocity should be matched to the air stream velocity (isokinetic sampling) to prevent oversampling of coarse dust at low sampler-to-air velocity ratios. Low velocity ratios are often encountered when using low flow rate, personal sampling pumps commonly used in underground mines. In this study, with a goal of employing mine-ready equipment, a personal sampler was adapted for area sampling of coarse coal dust in high-velocity ventilation air. This was done by adapting an isokinetic nozzle to the inlet of an Institute of Occupational Medicine (Edinburgh, Scotland) sampling cassette (IOM). Collected dust masses were compared for the modified IOM isokinetic sampler (IOM-MOD), the IOM without the isokinetic nozzle, and a conventional dust sampling cassette without the cyclone on the inlet. All samplers were operated at a flow rate typical of personal sampling pumps: 2 L/min. To ensure differences between collected masses that could be attributed to sampler design and were not influenced by artifacts from dust concentration gradients, relatively uniform and repeatable dust concentrations were demonstrated in the sampling zone of the National Institute for Occupational Safety and Health experimental mine gallery. Consistent with isokinetic theory, greater differences between isokinetic and non-isokinetic sampled masses were found for larger dust volume-size distributions and higher ventilation air velocities. Since isokinetic sampling is conventionally used to determine total dust concentration, and isokinetic sampling made a difference in collected masses, the results suggest when sampling for coarse coal dust the IOM-MOD may improve airborne coarse dust assessments over “off-the-shelf” sampling cassettes.     

Laboratory evaluation of pressure differential-based respirable dust detector tube

Assessment of exposure to occupational dusts is a first step in reducing exposures to harmful dust concentrations. A new type of respirable dust sampler was developed and compared side-by-side to personal gravimetric samplers in the laboratory. The new sampler correlates filter back pressure with mass accumulation to provide mid-shift- and end-of-shift determinations of cumulative exposure. The sampler uses a small low flow rate pump to draw dust through a small detector tube that contains a porous urethane foam respirable classification section and glass fiber filter that collects respirable dust. Six different coal dusts were aerosolized in a laboratory dust chamber and a total of 119 triplicate observations were obtained. For individual coal types, the correlation coefficients were between 0.87 and 0.97. The precision of the two methods was similar, with the percent relative standard deviation of the personal samplers of 12 percent and the new detector method of 14 percent. For all coal types tested th data were best described by a power function where delta P = 1.43 mass (0.85), with a correlation coefficient of 0.73. The method becomes more accurate at higher dust loadings such that all laboratory data with mass loadings greater than an equivalent concentration of 2 mg/m3 fall within +/- 25 percent of the power function. Assessment of the method under field conditions is in progress.     

Exposure to dust and particle-associated 1-nitropyrene of drivers of diesel-powered equipment in underground mining

A field study was conducted in two mines in order to determine the most suitable strategy for ambient exposure assessment in the framework of a European study aimed at validation of biological monitoring approaches for diesel exhaust (BIOMODEM). Exposure to dust and particle-associated 1-nitropyrene (1-NP) was studied in 20 miners of black coal by the long wall method (Czech Republic) and in 20 workers in oil shale mining by the room and pillar method (Estonia). The study in the oil shale mine was extended to include 100 workers in a second phase (main study). In each mine half of the study population worked underground as drivers of diesel-powered trains (black coal) and excavators (oil shale). The other half consisted of workers occupied in various non-diesel production assignments. Exposure to diesel exhaust was studied by measurement of inhalable and respirable dust at fixed locations and by personal air sampling of respirable dust. The ratio of geometric mean inhalable to respirable dust concentration was approximately two to one. The underground/surface ratio of respirable dust concentrations measured at fixed locations and in the breathing zones of the workers was 2-fold or greater. Respirable dust was 2- to 3-fold higher in the breathing zone than at fixed sampling locations. The 1-NP content in these dust fractions was determined by gas chromatography-mass spectrometry/mass spectrometry and ranged from 0.003 to 42.2 ng/m(3) in the breathing zones of the workers. In mine dust no 1-NP was detected. In both mines 1-NP was observed to be primarily associated with respirable particles. The 1-NP concentrations were also higher underground than on the surface (2- to 3-fold in the coal mine and 10-fold or more in the oil shale mine). Concentrations of 1-NP in the breathing zones were also higher than at fixed sites (2.5-fold in the coal mine and 10-fold in the oil shale mine). For individual exposure assessment personal air sampling is preferred over air sampling at fixed sites. This study also suggests that particle-associated 1-NP much better reflects the ambient exposure to diesel exhaust particles than dust concentrations. Therefore, measurement of particle-associated 1-NP is preferred over measurement of dust concentrations by gravimetry, when linking ambient exposure to biomonitoring outcomes such as protein and DNA adducts and excretion of urinary metabolites of genotoxic substances.     

Laboratory evaluation of a low-cost,real-time,aerosol multi-sensor

Exposure to occupational aerosols are a known hazard in many industry sectors and can be a risk factor for several respiratory diseases. In this study, a laboratory evaluation of low-cost aerosol sensors, the Dylos DC1700 and a modified Dylos known as the Utah Modified Dylos Sensor (UMDS), was performed to assess the sensors’ efficiency in sampling respirable and inhalable dust at high concentrations, which are most common in occupational settings. Dust concentrations were measured in a low-speed wind tunnel with 3 UMDSs, collocated with an aerosol spectrometer (Grimm 1.109) and gravimetric respirable and inhalable samplers. A total of 10 tests consisting of 5 different concentrations and 2 test aerosols, Arizona road dust and aluminum oxide, were conducted. For the Arizona road dust, total particle count was strongly related between the spectrometer and the UMDS with a coefficient of determination (R²) between 0.86–0.92. Particle count concentrations measured with the UMDS were converted to mass and also were related with gravimetrically collected inhalable and respirable dust. The UMDS small bin (i.e., all particles) compared to the inhalable sampler yielded an R² of 0.86–0.92, and the large bin subtracted from the small bin (i.e., only the smallest particles) compared to the respirable sampler yielded an R² of 0.93–0.997. Tests with the aluminum oxide demonstrated a substantially lower relationship across all comparisons. Furthermore, assessment of intra-instrument variability was consistent for all instruments, but inter-instrument variability indicated that each instrument requires its own calibration equation to yield accurate exposure estimates. Overall, it appears that the UMDS can be used as a low-cost tool to estimate respirable and inhalable concentrations found in many workplaces. Future studies will focus on deployment of a UMDS network in an occupational setting.     

Field testing of a personal size-selective bioaerosol sampler.

Existing samplers for the collection of bioaerosols have been designed with the aim of maintaining biological stability of the collected material, and in general do not select particles in accordance with international conventions for aerosol sampling. Many have uncharacterised sampling efficiencies and few are designed as personal samplers. If standard personal dust samplers are used for bioaerosols the viability of collected microorganisms may be compromised by dehydration. The objective of this study was to evaluate a novel personal bioaerosol sampler designed to collect the inhalable dust fraction and further subdivide the sample into thoracic and respirable fractions. The new sampler was tested to see whether it enhanced the survival of the collected microorganisms, and was assessed for ease of use in the field and in subsequent laboratory analyses. A number of occupation-related field sites were selected where large concentrations of bioaerosols were to be expected. The prototype sampler was found to be simple to use. Analysis could be carried out with similar efficiency either with all three fractions together for a total count, or separately for size selective data. The sampler performed at least as well as the standard IOM filter method but with the added advantage of size fractionation. The field trials showed that for sampling periods lasting several hours, microorganism survival within the sampler was adequate for culture and identification of the organisms present. This new sampler is now commercially available. In addition to bioaerosol sampling, the principle of size selective sampling using porous foams can be applied to other occupational hygiene problems, and also to indoor air monitoring of PM10 and PM2.5 concentrations.     

Performance of the RespiCon personal aerosol sampler in forest products industry workplaces

The RespiCon is a multistage virtual impactor that can be used as either a personal or an area sampler. Particles collected on the first stage of the RespiCon represent the respirable fraction of airborne particulate matter. Particles collected on the first and second stages represent the thoracic fraction, and particles collected on the first, second, and third stages represent the inhalable fraction. The RespiCon is available in two versions, one with photometric aerosol detection and a gravimetric version. In this study, the performance of the gravimetric version was examined in various forest products industry facilities. The precision of the RespiCon was assessed and its performance was compared with that of both a respirable cyclone and an inhalable dust sampler. In addition, some RespiCon samples were examined using scanning electron microscopy to determine physical particle size distribution. Under the conditions of this testing, the RespiCon appeared to be reasonably precise. For most sampling locations there was a close correspondence between measurements made with the RespiCon and the CIS personal inhalable sampler or the BGI-4 respirable cyclone. The results of microscopic examination of filters from the RespiCon were consistent with expected performance characteristics. The RespiCon is a useful sampling device for those situations in which it is important to simultaneously collect either personal or area samples of the respirable, thoracic, and inhalable fractions of airborne particulate matter.     

Field trials of an electret-based passive dust sampler in metal-processing industries

A prototype passive dust sampler using an electret to capture dust particles has been designed on the basis of previous laboratory investigations. The device weighs 15 g whereas conventional samplers, which require a pump and a battery, can weigh more than 1 kg. The electret used in the sampler is the same size as a standard sampling filter and can, to a large extent, be analysed in the same way, though sample weights tend to be small. The device has potential as both a static sampler and a personal sampler. Personal samplers have been assessed by field trials involving a number of volunteers, each wearing a passive sampler and one or more conventional samplers. The industries chosen for the trials were a hard-metal factory, platinum processing works and iron foundries, five factories in all being included in the tests. Correlations between the results of the passive samplers and those obtained using conventional inhalable dust samplers were good in four cases. Quantitative estimates of dust concentration require the electrical mobility of the dust to be known; and values were consistently high when scaled with measurements of aerosol electrical mobility made on the same occasion using a miniaturized electret device. In the instance where the passive sampler data could be compared with respirable dust samples the correlation was not particularly good.     

A field comparison of inhalable and thoracic size selective sampling techniques.

We measured inhalable, thoracic, and so-called "total" wood dust exposure in British Columbia lumber mill workers. Particle-size selective sampling was conducted using the GSP and Seven hole inhalable samplers, the PEM thoracic sampler and the 37-mm closed-face cassette "total" sampler. All measurements were full-shift personal samples, obtained from randomly selected workers. We obtained intersampler comparison data for the following pairs of instruments: GSP and 37-mm sampler; GSP and seven-hole sampler (SHS); and PEM and 37-mm sampler. The intersampler measurement ratios were estimated as: GSP/37-mm sampler = 4.2; GSP/SHS = 1.7; and PEM/37-mm sampler = 1.6. The GSP/37-mm sampler ratio is consistent with previously reported findings, while PEM/37-mm sampler and GSP/SHS ratios were both larger than expected. We found that in all comparisons, the measurement ratio had significant variability that was greatest at low ambient dust concentrations. Although it was not possible to attribute the source of the variability to specific sampler types, we concluded that the GSP sampler might be susceptible to "projectile" particles not normally aspirated, and may be vulnerable to direct aspiration of dust from accidentally contacted surfaces. The PEM was designed for environmental monitoring, and it is possible that it is unsuited to the higher particulate concentrations found in some occupational settings. Disparities among inhalable sampling techniques such as that between GSP and SHS should be investigated further in light of the proposed adoption of the inhalable method as an industrial standard.     

Performance of personal inhalable aerosol samplers in very slowly moving air when facing the aerosol source

While personal aerosol samplers have been characterized primarily based on wind tunnel tests conducted at relatively high wind speeds, modern indoor occupational environments are usually represented by very slow moving air. Recent surveys suggest that elevated levels of occupational exposure to inhalable airborne particles are typically observed when the worker, operating in the vicinity of the dust source, faces the source. Thus, the first objective of this study was to design and test a new, low cost experimental protocol for measuring the sampling efficiency of personal inhalable aerosol samplers in the vicinity of the aerosol source when the samplers operate in very slowly moving air. In this system, an aerosol generator, which is located in the centre of a room-sized non-ventilated chamber, continuously rotates and omnidirectionally disperses test particles of a specific size. The test and reference samplers are equally distributed around the source at the same distance from the centre and operate in parallel (in most of our experiments, the total number of simultaneously operating samplers was 15). Radial aerosol transport is driven by turbulent diffusion and some natural convection. For each specific particle size and the sampler, the aerosol mass concentration is measured by weighing the collection filter. The second objective was to utilize the new protocol to evaluate three widely used aerosol samplers: the IOM Personal Inhalable Sampler, the Button Personal Inhalable Aerosol Sampler and the 25 mm Millipore filter holder (closed-face C25 cassette). The sampling efficiencies of each instrument were measured with six particle fractions, ranging from 6.9 to 76.9 micro m in their mass median aerodynamic diameter. The Button Sampler efficiency data demonstrated a good agreement with the standard inhalable convention and especially with the low air movement inhalabilty curve. The 25 mm filter holder was found to considerably under-sample the particles larger than 10 micro m; its efficiency did not exceed 7% for particles of 40-100 micro m. The IOM Sampler facing the source was found to over-sample compared with the data obtained previously with a slowly rotating, freely suspended sampler in a low air movement environment. It was also found that the particle wall deposition in the IOM metallic cartridge was rather significant and particle size-dependent. For each sampler (IOM, Button and C25) the precision was characterized through the relative standard deviation (RSD) of the aerosol concentration obtained with identical samplers in a specific experiment. The average RSD was 14% for the IOM Sampler, 11% for the Button Sampler and 35% for the 25 mm filter cassette. A separate set of experiments, performed with the Simplified Torso showed that in very slowly moving air a personal sampler can be adequately evaluated even when it is not attached to a body but freely suspended (confirming the data reported previously).     

Laboratory and field testing of sampling methods for inhalable and respirable dust

The performance of four sampling devices for inhalable dust and three devices for respirable dust was tested with different kinds of dusts in the laboratory and in the field. The IOM sampler was chosen as the reference method for inhalable dust, and the IOM sampler provided with the porous plastic foam media was used as the reference method for respirable dust. The other tested instruments were the Button sampler, the optical Grimm aerosol monitor, and the Dekati two-stage cascade impactor with cutoff sizes of 10 and 4 mu m. The study confirmed the applicability of the IOM and Button samplers. The new foam product followed the respirable criteria well. However, the foam sampler was unstable for measuring inhalable dust, probably due to its moisture absorption. In addition, high dust loads should be avoided with the foam sampler due to increase in filtering efficiency. The concentrations of inhalable dust measured with the Button sampler, the Grimm monitor, and the impactor sampler were usually close to those measured with the reference sampler. On the other hand, impactor sampling yielded higher respirable dust concentrations than the reference method in the field, which may have been caused by particle bounce; high dust loads should be avoided while using the impactor. The results also showed that the Grimm monitor enables real-time dust concentration determinations that are accurate enough for routine monitoring of occupational exposure and for testing efficiency of control measures in workplaces.     

Personal sampling in parallel with open-face filter cassettes and IOM samplers for inhalable dust--implications for occupational exposure limits

Parallel personal sampling was carried out with the open-face filter cassette and the IOM sampler for inhalable dust for nine types of organic dust. Parallel samples numbering 749 were obtained from 152 plants. Extremely large values and outliers were disregarded, and the remaining data for each type of dust were divided into subsets according to type of product or work task, and analyzed with the aid of linear regression. The coefficient of regression for each subset ranged between 0.2 and 0.7. Hypothetical occupational exposure limits (OELs) for inhalable dust were calculated based on the linear relation obtained between the dust concentrations measured with the open-face filter cassette and the IOM sampler. The fraction of person days with time-weighted average (TWA) concentrations exceeding the calculated hypothetical OELs for inhalable dust was obtained from the distribution of measured TWA inhalable dust concentrations. Based on the results of this study and the difference in sampling efficiency for large particles between the two samplers, it was concluded that the numerical value of the OEL for inhalable dust may be set at approximately twice the numerical value of the corresponding limit value for "total dust." Additional consideration of recently discovered health effects, and technical and economical factors may result in other numerical values of future OELs for inhalable dust.     

Dynamic monitoring of the dust pickup efficiency of vacuum cleaners

This study evaluated a new method that uses an optical aerosol photometer for dynamically monitoring dust pickup efficiency during vacuuming. In the first stage of this study the new method was compared with built-in dirt sensors installed by vacuum cleaner manufacturers. Through parallel testing it has been shown that the widely available built-in dirt sensors are not sensitive enough to register small (< 53 microm) dust particles. Therefore, only the optical photometer was used in the rest of the experiments of this study to monitor the dust pickup efficiency while the vacuum cleaner was operated with different nozzles on clean and soiled carpet and vinyl sheet flooring. This method also was used to monitor dust pickup efficiency when vacuuming carpets originating from lead-contaminated homes. The dust pickup efficiencies obtained with the optical aerosol photometer have been compared with the surface lead concentrations found during different stages of cleaning. Results indicate that the dust mass concentration registered with the optical aerosol photometer at the nozzle outlet correlates well with the dust mass collected in the vacuum cleaner filter bag and with the surface lead level. Therefore, dynamic dust pickup monitoring can provide valuable information about the efficiency of cleaning when a vacuum cleaner is used. This suggests that a small aerosol photometer similar to a light-scattering smoke detector would be beneficial in vacuum cleaners used for cleaning surfaces contaminated with leaded dust and biological particles (including allergens).     

Assessment of increased sampling pump flow rates in a disposable,inhalable aerosol sampler

A newly designed, low-cost, disposable inhalable aerosol sampler was developed to assess workers personal exposure to inhalable particles. This sampler was originally designed to operate at 10 L/min to increase sample mass and, therefore, improve analytical detection limits for filter-based methods. Computational fluid dynamics modeling revealed that sampler performance (relative to aerosol inhalability criteria) would not differ substantially at sampler flows of 2 and 10 L/min. With this in mind, the newly designed inhalable aerosol sampler was tested in a wind tunnel, simultaneously, at flows of 2 and 10 L/min flow. A mannequin was equipped with 6 sampler/pump assemblies (three pumps operated at 2 L/min and three pumps at 10 L/min) inside a wind tunnel, operated at 0.2 m/s, which has been shown to be a typical indoor workplace wind speed. In separate tests, four different particle sizes were injected to determine if the sampler's performance with the new 10 L/min flow rate significantly differed to that at 2 L/min. A comparison between inhalable mass concentrations using a Wilcoxon signed rank test found no significant difference in the concentration of particles sampled at 10 and 2 L/min for all particle sizes tested. Our results suggest that this new aerosol sampler is a versatile tool that can improve exposure assessment capabilities for the practicing industrial hygienist by improving the limit of detection and allowing for shorting sampling times.     

Personal thoracic CIP10-T sampler and its static version Cathia-T

A specific version of the personal aerosol sampler CIP 10 was designed, named CIP10-T, for sampling the conventional CEN thoracic fraction. A static sampler, named CATHIA, was also designed. It uses the same sampling head, but the size selected particles are collected onto a filter. The combined particle efficiency of the aspiration slot and the selector was measured in a horizontal wind tunnel at low air velocity, close to 16 cm s⁻¹. The flow rate of both samplers was fixed at its nominal value, i.e., 7 l min⁻¹. Two different methods were used: the former was based on the Aerodynamic Particle Sizer (TSI); the latter used the measurement of particle size distribution of the collected samples by the Coulter technique. For the CIP10-T sampler, the particle collection efficiency onto the rotating cup was also measured. For both samplers bias and accuracy maps have been calculated, following the recommendations of a new CEN standard about sampler performance. The bias does not exceed 10% in absolute value for both samplers, within a large range of particle size distribution of the total aerosol. For the CIP10-T sampler, the accuracy map exhibits a large area where the accuracy is better than 10%, corresponding for example to 4 μm≤MMAD≤14 μm for GSD=2. For the same geometric standard deviation, the accuracy is still better than 20% for 15 μm≤MMAD≤21 μm. For the CATHIA-T sampler, the accuracy map can be roughly divided into two parts. The accuracy remains better than 10% for MMAD≤12 μm, and it remains between 10 and 20% for coarser aerosols, with 13 μm≤MMAD≤20 μm, provided GSD≥2.     

Sampling of high amounts of bioaerosols using a high-volume electrostatic field sampler

For studies of the biological effects of bioaerosols, large samples are necessary. To be able to sample enough material and to cover the variations in aerosol content during and between working days, a long sampling time is necessary. Recently, a high-volume transportable electrostatic field sampler for collection of fine particles has been described. The aim of this study was to investigate whether this sampler can be used for collection of high amounts of authentic bioaerosols that can subsequently be used for biological analysis. The investigation was carried out at a biofuel plant in a straw storage room and in a boiler room over two seasons. The sampled dust was quantified in terms of mass and characterized regarding microbial components and compared with dust sampled by Gravikon and GSP samplers. For the electrostatic field sampler, a prefilter was used to remove large objects. The prefilter was characterized for particle penetration and this testing indicated that the prefilter did not remove particles up to 10 mum, and therefore respirable dust was sampled by the electrostatic field sampler. Using the electrostatic field sampler in the straw storage and in the boiler room, 330 and 315 mg dust (net recovery of the lyophilized dust) was sampled during a period of 7 days, respectively. The sampling rates of the electrostatic field samplers were between 1.34 and 1.96 mg dust per hour, the value for the Gravikon was between 0.083 and 0.108 mg dust per hour and the values for the GSP samplers were between 0.0031 and 0.032 mg dust per hour. The standard deviations of replica samplings and the following microbial analysis using the electrostatic field sampler and GSP samplers were at the same levels. The exposure to dust in the straw storage was 7.7 mg m(-3) when measured by the electrostatic field sampler and 11.8 mg m(-3) when measured by the GSP inhalable dust sampler. The quantity (amount per mg dust) of total fungi, Aspergillus fumigatus, total bacteria, endotoxin and mesophilic actinomycetes sampled by the electrostatic field samplers and the Gravikon samplers varied within the same season by a factor smaller than four. The quantities of some microbial components were higher in the dust collected with all samplers in March than in August. In conclusion, by using the electrostatic field sampler, it was possible to sample replicas of large authentic aerosol samples that can be used, e.g. biological analysis.     

Comparison of a passive aerosol sampler to size-selective pump samplers in indoor environments

The objective of this work was to investigate the ability of the Wagner-Leith passive aerosol sampler to measure indoor exposures over periods of 24 hours to 2 weeks. An automated analysis technique was developed so that lower aerosol concentrations could be sampled over shorter time periods. A test of the new analytical method against a manual method showed good agreement. The passive sampler was tested alongside three pump-operated, size-selective samplers in indoor environments. Generally, good correlation with the active samplers was observed. Correlation with a personal impactor with uncoated substrates was not statistically significant, but the cyclone, MS&T impactor, and overall correlations had R(2) values of 0.73-0.88. Combining these data with a previous study produced an R(2) of 0.96 between passive and active results. Large discrepancies (up to 147%) between passive and personal impactor results were observed and were attributed to particle bounce in the impactor, passive sampler imprecision due to few collected fine particles, and problems with detection of organic particles in the passive sampler. The Wagner-Leith sampler has now been tested over five orders of magnitude in mass concentration, in which it has proved useful for obtaining aerosol size distributions, mass fractions, qualitative elemental analysis, and morphology of individual particles. The sampler has several limitations, including increased sensitivity to contamination when fewer particles are collected, uncertainties in sampling semi-volatile particles, and the need for some expertise and expense to analyze the passive samples.     

Field comparison of inhalable aerosol samplers applied in the european rubber manufacturing industry

Several studies have been done in Europe to evaluate exposure to dust and fumes in the rubber industry. However, different aerosol sampling devices have been used which perform differently depending on the environmental conditions and particle size distribution. To compare measurements of rubber dust and fumes among countries and surveys we initiated a field comparison of personal inhalable samplers using a novel reference inhalable aerosol sampler (CALTOOL). Measurements were done in four factories in the Netherlands, Sweden, Poland and Germany in the mixing and milling and curing department. The Seven-hole sampler, PAS-6 sampler, Millipore (25 and 37 mm) cassette, IOM sampler and a Polish sampler were mounted on the reference CALTOOL device and used simultaneously. All samplers except the IOM sampler under-sampled inhalable dust. To compare measurements from different studies and countries, correction factors should be applied to all but the IOM sampler, which was the only sampler that performed similar to the CALTOOL sampler.     

Critique of 1985 ACGIH report on particle size-selective sampling in the workplace

The criteria recently proposed by ACGIH for judging the acceptability of respirable and other dust fraction samplers are analyzed. Implications on the sampling of workplace aerosol are determined. With the consideration of both bias and imprecision, the overall accuracy limited by the criteria is estimated for the sampling of coal mine dust as characterized by various researchers. The accuracy limits thus found appear to be excessively broad. As an example with actual workplace dust distributions in the sampling of a single aerosol (mass median diameter = 18.6 micrometers and geometric standard deviation = 2.3) with respirable dust concentration near 2 mg/m3, two samplers acceptable according to the proposed criteria could be found giving respirable dust measurements equal to 0.71 mg/m3 and 4.3 mg/m3 (even after excluding 5% of the low and high measurements from each sampler, respectively). Large variation in samplers acceptable according to the criteria is found for many other distributions as well; this indicates that tighter requirements are necessary. Seldom attained are both the single-sample +/- 25% accuracy at the 95% confidence level required of sampling/analytical methods endorsed by the National Institute for Occupational Safety and Health (NIOSH) and the tighter ISO dust fraction measurement requirement that 67% of the measurements of a sampled dust fall within 10% of a true value. Suggestions are given for sharpening the criteria without eliminating all samplers from acceptability.