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.     

Collection efficiency of a personal sampler for microbiological aerosols.

A modified personal impinger (MPI) for sampling airborne microorganisms was tested for collection efficiency with the jet nozzle placed at various positions above and below the liquid surface. The sampler was operated with 10 mL of water and sampling rates between 1.08 and 3.4 L/min. The collection efficiencies for a polydisperse aerosol of diethylhexyl phthalate (DEHP) and monodisperse aerosols of polystyrene latex particles (ULP) were determined with an optical particle counter. The results show that a test aerosol generated from a suspension, such as ULP, gives test results that agree better with theoretical predictions than a polydisperse oil aerosol such as DEHP. The measured aerodynamic 50% cutoff diameters (D50) agreed with those predicted from impaction theory with the jet nozzle 4 mm from the flask bottom. For preservation of viability during sampling of microorganisms, it is common to use impingers with the jet nozzle above the liquid surface. These tests showed that if the MPI is operated with the jet nozzle above the liquid surface, D50 will be displaced toward larger particle sizes because the jet-to-plate distance/jet diameter ratio increases substantially when a soft impaction surface such as the liquid is used. The increased D50 could to some extent be compensated for by increasing the flow rate. An increased flow rate will, however, result in more losses because of aerosol regeneration.     

Chamber evaluation of a personal, bioaerosol cyclone sampler

A personal cyclone sampler (cyclone) was operated in a 0.9-m3 chamber, side by side with a 25-mm filter sampler (filter) and either a slit impactor (Air-O-Cell) or a single-stage, multiple-hole, agar impactor (N6). Aerosols of two fungal spores were collected for 5 min to 5 hr-Aspergillus versicolor: 10, 20, 40, 80, 160, and 320 min; concentration: 10(2)-10(5) spore m(-3); Scopulariopsis brevicaulis: 5, 10, 15, 20, 25, and 30-min; concentration: 10(3)-10(5) spore m(-3) (six replicates for each sampling time). For each fungus, air concentrations were determined by a 15-channel optical particle counter (particle m(-3); N = 36), microscopy (spore m(-3); cyclone and filter, N = 36; Air-O-Cell, N = 18), culture (colony forming unit m(-3); cyclone and filter, N = 36; N6, N = 18), and polymerase chain reaction (cell equivalent m(-3); cyclone and filter, N = 36). Samplers were significantly correlated with each other as were the three analyses (correlation coefficients = 0.79-1.00 and 0.87-0.98, respectively). Ratios were calculated for simultaneous measurements with the cyclone and comparison samplers and for paired colony:spore, colony:cell equivalent, and cell equivalent:spore measurements for the cyclone and filter samples. The cyclone equaled or underestimated the other samplers for both fungi and all analyses (mean ratio: 0.75-1.04). A. versicolor colony and cell equivalent measurements exceeded spore measurements although microscopy should detect all spores not just culturable ones, perhaps due to difficulty observing the smaller spores or detection of DNA in cell fragments in addition to intact spores. Plots of the ratios of paired measurements against their averages identified biases between samplers and analyses. For example, ratios were correlated with spore concentration, and there was greater uncertainty at lower concentrations. These chamber tests have shown that the cyclone is suitable for collection of airborne fungal spores over a wide concentration range and time period and for analysis by microscopy, culture, and polymerase chain reaction.     

Field evaluation of a personal, bioaerosol cyclone sampler

A personal cyclone sampler (cyclone) was operated continuously alongside a 25-mm filter sampler (filter), a slit impactor (Burkard slide), and a high-volume cyclone sampler (Burkard cyclone) at an outdoor location with abundant naturally occurring fungi (N = 30; sampling time: 12.5 +/- 2.3 hr). Air concentrations (spore m(-3)) of 28 fungal groups were determined for all samplers by microscopy. Cyclone performance was judged using various indices to determine if it agreed with the other samplers in determination of the frequencies with which the fungal groups were observed, as well as their proportions of the total air concentration. Fungal diversity estimates were similar for all samplers and in the range of what has been reported nationally, i.e., observation of 9-11 equal groups per sample, but spore concentration dominated by 2-3 groups. Plots of paired cyclone:comparison sampler ratios against average concentrations identified biases. For example, ratios were correlated with concentration and there was greater uncertainty at lower concentrations. Mean ratios for cyclone:filter comparisons were not significantly different from one for ascospores, Aspergillus-Penicillium spp., basidiospores, Cladosporium spp., or total spore m(-3). However, agreement was less consistent with the Burkard slide (0.74, 1.12, 0.91, 1.09, and 0.92, respectively) and the Burkard cyclone (2.31, 1.62, 1.43, 1.91, and 1.33, respectively). Concentrations of cell equivalent m(-3) also were determined for the filter and two cyclone samples by polymerase chain reaction. Cell equivalents for Aspergillus fumigatus and Penicillium brevicompactum were compared with Aspergillus-Penicillium spp. spores, and Cladosporium cladosporioides and Cladosporium herbarum cell equivalents were compared with Cladosporium spp. spores. Cell equivalent:spore ratios below one for A. fumigatus and P. brevicompactum indicated that these species comprised smaller factions of total spores or were collected less efficiently than the larger C. cladosporioides and C. herbarum spores. The personal cyclone was shown to be suitable for collection of ambient airborne fungal spores and for analysis by microscopy and polymerase chain reaction.     

扩散法被动式甲醛个体监测器（Ⅱ型）的研制

介绍了一种基于气体分子扩散原理的被动式甲醛个体采样器，它是在Ⅰ型采样器的基础上完成的。采用甘油（２０％）／偏重亚硫酸钠（０．２５％）浸渍的定量滤纸（φ４２ｍｍ）作为吸收层，空气中甲醛扩散到吸收层上，形成稳定的化合物。采样一定时间后，取出吸收层，洗脱后，用ＡＨＭＴ化学比色法测定所采集到的甲醛。这种采样器的平均采样速率为８３ｍｌ／ｍｉｎ，标准偏差为７．２ｍｌ／ｍｉｎ，与有动力吸收管采样的方法相比较，总不确定度小于±２５％。     

A personal air sampler for pesticides

A sampling train consisting of a 13-mm filter followed by a tube containing Chromosorb 102 was developed for measurement of personal exposure to pesticides. Recoveries from cellulose ester filters and Chromosorb 102 for thirteen pesticides were generally 90% or greater. Side-by-side sampling in a pesticide formulation plant with midget impingers and 37-mm filters demonstrated that the trains, impingers and filters gave similar results.     

Effect of altitude on personal respirable dust sampler calibration.

Air sampling instruments often are used at altitudes other than the altitude at which they were calibrated. This investigation quantitates the effect of personal samplers and provides empirical relationships for adjusting the calibration mark for use at any altitude.     

扩散法被动式挥发性有机化合物个体监测器的研制

研制了一种以单层活性炭颗粒作为吸收介质的被动式挥发性有机化合物个体监测器。空气中挥发性有机化合物依据分子扩散原理传质到采样器中，并吸附到活性炭上。采样后，取出活性炭吸附层，用二硫化碳洗脱，再用气相色谱法定性和定量。对监测器进行了实验室性能评价和现场验证。结果表明，采样器在风速２０～１５０ｃｍ／ｓ，相对温度１０％～８０％，温度－１０～３５℃范围内使用，采样速率分别为６０ｍｌ／ｍｉｎ（苯）、５４ｍｌ／ｍｉｎ（甲苯）、５４ｍｌ／ｍｉｎ（氯仿）和４９ｍｌ／ｍｉｎ（对－二甲苯），相对标准差小于５％。在现场与有泵活性炭管采样相比较，本个体监测器测定空气中挥发性有机化合物的总不确定度分别为１２％（苯）、１２％（甲苯）、２６％（对－二甲苯）和１６％（氯仿），可适用于室内空气污染和个体接触量的监测。     

Measurement of personal exposure to NO2 in Sweden--evaluation of a passive sampler.

A passive (filter badge) sampler for personal NO2 exposure measurements was tested in a laboratory setting (exposure chamber), and in the field--outdoors, during periods of high relative humidity (mean 85%) and low temperature (-5 to +10 degrees C), and indoors, in an ice-hockey arena--using chemiluminescence as a reference method. Parallel measurements of NO2 in the exposure chamber (concentration range 100-825 micrograms NO2/m3) for 15, 30, and 60 min sampling periods, showed good agreement between methods. The concentrations obtained with passive samplers were 78 to 122% (mean 94%, SD +/- 11, N = 39) of those obtained with chemiluminescence, using a sampling rate (K'OG) of 0.14 cm/sec. The detection limits were 320, 160, and 80 micrograms NO2/m3 for 15, 30, and 60 minutes of sampling, respectively. Outdoors (concentration range 15-102 micrograms NO2/m3, concentrations obtained with passive samplers were consistently lower than concentrations obtained with chemiluminescence (mean 79%, SD +/- 9.3%, range 61-95%, N = 25), using the K'OG of 0.14 of cm/sec (Passive samplerNO2 = 0.67ChemilumNO2 + 4.5). A better agreement between concentrations obtained with passive samplers and chemiluminescence was achieved with a K'OG of 0.11 cm/sec (mean 100%, SD +/- 12%, range 78-121%, Passive samplerNO2 = 0.84 ChemilumNO2 + 6.4). Indoors (concentration range 210-3895 micrograms NO2/m3), concentrations obtained with passive samplers were 70 to 113% (mean 90%, SD +/- 16%) of the concentrations obtained with chemiluminescence (Passive samplerNO2 = 1.00ChemilumNO2 - 93) using a K'OG of 0.10 cm/sec. Duplicate samples collected indoors N = 18) and outdoors (N = 31) showed a variability (coefficient of variation, or CV) of less than 6%. It was concluded that the passive sampler is useful for measuring personal daily exposure as well as peak exposure. It is necessary to determine sampling rates for various environmental conditions.     

A personal dust sampler simulating variable human lung function.

In a prototype of a new personal dust sampling system (PDS) the speed of air sampling in the breathing zone is related to the pulmonary ventilation rate of the wearer, using the correlation between pulmonary ventilation and pulse rate that is monitored by electrodes fastened on the sampler wearer's chest. The method of calibration and the results of dust chamber and field measurements are presented. The prototype of the new sampler was tested in a lead and zinc smelting plant against a routine stationary sampler and typical personal sampler. Personal exposure using all the above mentioned devices has also been assessed, and the PDS gives satisfactory results in use.     

Design and validation of a high-flow personal sampler for PM2.5

A high-flow personal sampler (HFPS) for airborne particulate matter has been developed and fully characterised, and validation tests have been carried out. The sampler is a low-cost gravimetric instrument designed to collect particulate matter with a 50% cut point at 2.5 microm aerodynamic equivalent diameter (PM2.5), where size selection is achieved by the use of porous polyurethane foam. Development of a porous foam selector was chosen over a cyclone or impactor due to the lightweight, low-cost, and compact design that could be achieved. The sampler flow rate of 16 1/min is achieved using a portable, flow-controlled pump; this flow rate is far higher than that of conventional personal samplers and the HFPS can therefore be used for personal sampling in the ambient environment over short sampling periods of much less than 24 h. The HFPS is currently being used in a study of particle exposure of urban transport users (cyclists, car drivers, bus and Underground rail passengers) where personal sampling over short time periods representing typical commuter journey times is required. The HFPS was fully characterised in chamber studies with a TSI aerodynamic particle sizer (APS). The sampler was then validated against a co-located U.S. EPA Federal Reference PM2.5 Well Impactor Ninety Six (WINS) and a KTL cyclone, and parallel testing was performed. Initial testing showed some penetration of particles through the porous foam structure; applying an oil coating to the foam eliminated this problem. Chamber testing was carried out on a number of different selector prototypes, with the final design giving a 50% penetration diameter (i.e., d50) of 2.4 microm at 16 1/min. The new sampler exhibited good agreement in three sets of co-located tests with established samplers, and parallel testing showed excellent agreement between paired HFPS samplers.     

A personal sampler for aircraft engine cold start particles: laboratory development and testing

Industrial hygienists in the U.S. Air Force are concerned about exposure of their personnel to jet fuel. One potential source of exposure for flightline ground crews is the plume emitted during the start of aircraft engines in extremely cold weather. The purpose of this study was to investigate a personal sampler, a small tube-and-wire electrostatic precipitator (ESP), for assessing exposure to aircraft engine cold start particles. Tests were performed in the laboratory to characterize the sampler's collection efficiency and to determine the magnitude of adsorption and evaporation artifacts. A low-temperature chamber was developed for the artifact experiments so tests could be performed at temperatures similar to actual field conditions. The ESP collected particles from 0.5 to 20 micro m diameter with greater than 98% efficiency at particle concentrations up to 100 mg/m(3). Adsorption artifacts were less than 5 micro g/m(3) when sampling a high concentration vapor stream. Evaporation artifacts were significantly lower for the ESP than for PVC membrane filters across a range of sampling times and incoming vapor concentrations. These tests indicate that the ESP provides more accurate exposure assessment results than traditional filter-based particle samplers when sampling cold start particles produced by an aircraft engine.     

Numerical determination of personal aerosol sampler aspiration efficiency

In this work the determination of the aspiration efficiency of personal aerosol samplers, commonly used in occupational exposure assessment, is investigated by means of CFD techniques. Specifically, it will be described a code to calculate the particle trajectories in a given flow field. At the present state the code considers only the effects of the mean flow field on the particle motion, whereas the turbulent diffusion effects are neglected. Comparisons with experimental measurements are also given in the framework of a research contract, supported by the European Community, with several experimental contributions from the participants. The main objective of the European research is to develop a new approach to experimentation with airborne particle flows, working on a reduced scale. This methodology has the advantage of allowing real-time aerosol determination and use of small wind tunnels, with a better experimental control. In this article we describe how the methodology has been verified using computational fluid dynamics. Experimental and numerical aspiration efficiencies have been compared and the influence of gravity and turbulence intensity in full and reduced scale has been investigated. The numerical techniques described here are in agreement with previous similar research and allow at least qualitative predictions of aspiration efficiency for real samplers, taking care of orientation from the incoming air flow. The major discrepancies among predicted and experimental results may be a consequence of bounce effects, which are very difficult to eliminate also by greasing the sampler surface.     

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.     

Laboratory evaluation of the CIP 10 personal dust sampler

The "capteur individuel de poussiere" CIP 10 personal dust sampler--developed by the Centre d'Etudes et Recherches de Charbonnages de France (CERCHAR) research organization--is a small, quiet, lightweight unit which samples at a flow rate of 10 L/min. It is a three-stage sampler, using two stages to remove nonrespirable dust particles and one stage to collect the respirable fraction. Airflow through the sampler is induced by the third stage, which is a rotating collector cup that contains a fine grade sponge. Laboratory tests were conducted in a dust chamber using aerosols of Arizona road dust, coal dust and silica dust. Aerosol concentrations measured with the CIP 10 were compared to those measured with the coal mine dust personal sampler unit used in the United States. The results of this study showed that aerosol concentrations measured with the CIP 10 were linearly related to those obtained with the coal mine dust personal sampler. The relationship, however, was dependent on preselector configuration and aerosol characteristics. The collection medium allows some small particles (less than 3 microns) to pass through the sampler without being collected. As much as 13% (by weight) of the aerosol that penetrated through the preseparating stages was exhausted from the sampler.