Size-separated sampling and analysis of isocyanates in workplace aerosols. Part I. Denuder--cascade impactor sampler

Isocyanates in the workplace atmosphere are typically present both in gas and particle phase. The health effects of exposure to isocyanates in gas phase and different particle size fractions are likely to be different due to their ability to reach different parts in the respiratory system. To reveal more details regarding the exposure to isocyanate aerosols, a denuder-impactor (DI) sampler for airborne isocyanates was designed. The sampler consists of a channel-plate denuder for collection of gaseous isocyanates, in series with three-cascade impactor stages with cut-off diameters (d(50)) of 2.5, 1.0 and 0.5 mum. An end filter was connected in series after the impactor for collection of particles smaller than 0.5 mum. The denuder, impactor plates and the end filter were impregnated with a mixture of di-n-butylamine (DBA) and acetic acid for derivatization of the isocyanates. During sampling, the reagent on the impactor plates and the end filter is continuously refreshed, due to the DBA release from the impregnated denuder plates. This secures efficient derivatization of all isocyanate particles. The airflow through the sampler was 5 l min(-1). After sampling, the samples containing the different size fractions were analyzed using liquid chromatography-mass spectrometry (LC-MS)/MS. The DBA impregnation was stable in the sampler for at least 1 week. After sampling, the DBA derivatives were stable for at least 3 weeks. Air sampling was performed in a test chamber (300 l). Isocyanate aerosols studied were thermal degradation products of different polyurethane polymers, spraying of isocyanate coating compounds and pure gas-phase isocyanates. Sampling with impinger flasks, containing DBA in toluene, with a glass fiber filter in series was used as a reference method. The DI sampler showed good compliance with the reference method, regarding total air levels. For the different aerosols studied, vast differences were revealed in the distribution of isocyanate in gas and different particle size fractions. The opportunity to obtain detailed information regarding the distribution of isocyanates in aerosols in addition to the total air levels make the DI sampler a valuable tool for studies of possible health effects in the different parts of the airways.     

Evaluation of dust exposure in asbestos cement manufacturing operations.

Previous investigations of the health of workers of the asbestos cement industry have demonstrated dose-response relationships for the diffuse radiographic changes of asbestosis and pulmonary function impairment. Studies of the mortality experience of past employees have also identified levels of cumulative exposure above which an excess of respiratory cancer could be detected. These epidemiologic studies were based on particulate concentrations determined by the midget impinger. We attempted to develop information that might lead to conversion of particulate to fiber concentrations in the industry in order that the risk assessment could be related to the current membrane filter methods. Pairs of impinger and membrane filter samples were taken in the various areas of the plant. Personal samples were also taken to determine the current exposure of workers. The ratio of fiber concentration to particle count varied from 0.63 to 2.5. Por correlation (0.18) was obtained at low fiber and particle counts and good correlation (0.91) was demonstrated in dustry areas where asbestos and silica were handled in a dry form. The concentration of fibers in 80% of the personal samples was less than 2 fibers/cc, and 60% were less than 0.5 fibers/cc. The results also show that no one conversion factor can be used for all areas of this type of operation.     

The mutagenicity of emissions from eight binder systems used in steel foundries

Emissions generated when molten steel was poured into sand molds fabricated with eight different binder systems were collected separately and tested for mutagenic activity using the Ames Salmonella assay. The sampling device consisted of an initial 8 X 10 in. glass fiber filter in a custom fabricated apparatus through which air was drawn using a Hi-Vol motor and fan. A portion of the airstream, which passed this filter, was in turn passed through a smaller glass fiber filter and then into two glass impingers filled with ice-cold methanol. All the binder systems generated material, which induced mutations in the absence of added S-9 extract, and in all emissions a higher level of activity was found when S-9 was added. In the presence of S-9, the shell-core system produced by far the most mutagenic activity followed by the oil-clay-cereal system. The green sand, furan and Kold Set systems produced much lower levels while the two reclaimed sand systems and sodium silicate system were intermediate.     

Design and evaluation of a solid sampler for the monitoring of airborne 1,6-hexamethylene diisocyanate (HDI) and its prepolymers in two-component spray painting.

An active, solvent-free solid sampler was developed for the collection of 1,6-hexamethylene diisocyanate (HDI) aerosol and prepolymers. The sampler was made of a filter impregnated with 1-(2-methoxyphenyl)piperazine contained in a filter holder. Interferences with HDI were observed when a set of cellulose acetate filters and a polystyrene filter holder were used; a glass fiber filter and polypropylene filter cassette gave better results. The applicability of the sampling and analytical procedure was validated with a test chamber, constructed for the dynamic generation of HDI aerosol and prepolymers in commercial two-component spray paints (Desmodur N75) used in car refinishing. The particle size distribution, temporal stability, and spatial uniformity of the simulated aerosol were established in order to test the sampler. The monitoring of aerosol concentrations was conducted with the solid sampler paired to the reference impinger technique (impinger flasks contained 10 mL of 0.5 mg/mL 1-(2-methoxyphenyl)piperazine in toluene) under a controlled atmosphere in the test chamber. Analyses of derivatized HDI and prepolymers were carried out by using high-performance liquid chromatography and ultraviolet detection. The correlation between the solvent-free and the impinger techniques appeared fairly good (Y = 0.979X-0.161; R = 0.978), when the tests were conducted in the range of 0.1 to 10 times the threshold limit value (TLV) for HDI monomer and up to 60 micrograms/m3 (3 U.K. TLVs) for total -N=C=O groups.     

Comparative personal exposures to organic dusts and endotoxin

The aims of the study were to provide valid comparative data for personal exposures to dust and endotoxins for different occupations and to calculate comparative data for the contamination of organic dusts with endotoxin. Nine different occupational settings were studied, drawn from the textile, agricultural and animal handling industries. Samples were collected by personal sampling techniques, using the Institute of Occupational Medicine (IOM) sampling head, glass fibre filters and rechargeable sampling pumps. The dust exposures were calculated by gravimetric analysis and using the calculated volume of air sampled were expressed as mg/m3. Endotoxin exposures were measured using a simple water extraction from the collected dusts, followed by a quantitative turbidimetric assay. Results were expressed as ng/m3, using the calculated volume of air sampled. In addition, the levels of the contamination of dusts with endotoxin for individual industries were expressed as ng/mg of collected dust. Two hundred and fifty-nine samples, collected from 9 different industries and across 36 different sites were analysed. This represented a sampling rate of 25% for the total work force. The average sampling time was 4.62 h. For all the dusts collected, a significant correlation between the collected dust and endotoxin was seen (r = 0.7 and p < 0.001). The highest dust exposures occurred during cleaning activities (grain handling: 72.5 mg/m3). The individuals exposed to the highest median level of dust and endotoxin were the animal handlers (poultry handlers, dust: 11.53 mg/m3, endotoxin: 71,995 ng/m3). Weaving and mushroom cultivation had the lowest exposures for dust and endotoxins. The mostly highly contaminated dusts (median values expressed as ng of endotoxin per mg of collected dust) were found in the animal handling (poultry: 1,030 ng/mg, swine: 152 ng/mg) and cotton spinning (522 ng/mg) industries. Processing of cotton and wool fibres was found to reduce the levels of contamination of dusts with endotoxin. In the study, valid comparative data for personal exposures to organic dusts and endotoxins have been presented. The highest exposures were found amongst animal handlers and during cleaning activities. The results highlight that dust exposures are greater in a number of industries than the set exposure standards. In addition, endotoxin exposures are found to be greater than levels at which harmful effects have been demonstrated.     

工作场所空气中矿物油烟雾浓度测定方法的研究

目的 研究工作场所空气中矿物油烟雾浓度的测定方法.方法 选择混合纤维滤膜、超细玻璃纤维滤膜、慢性定量滤纸、微孔滤膜4种滤料,用2种粉尘采样器在生产现场进行短时间高采气流量和长时间低采气流量采样,用电子分析天平称重,以滤料的采样效率和增量大小为主要指标.分析比较不同滤料对矿物油烟雾的采样吸附能力.结果 混合纤维滤膜在10～20 L/min的采气流量和采样10～15min(10L/min可采样20min),平均采样效率为95.61%,增量在0.87～2.60mg;超细玻璃纤维滤膜在10～20L/min采样流量下,采样10～20min,平均采样效率为97.57%,增量在0.75～2.47mg;在5～10L/min采样流量下,采样10～20 min,慢性定量滤纸和微孔滤膜平均采样效率分别为48.94%和63.15%,增量分别为0.75～2.15 mg和0.23～0.85 mg.在采气流量为3.5 L/min、采样时间为100～166 min时,超细玻璃纤维滤膜和混合纤维滤膜的平均采样效率分别为94.44%和93.45%,平均增量超细玻璃纤维滤膜为1.28 mg,混合纤维滤膜为0.78 mg;慢性定量滤纸和微孔滤膜平均采样效率分别为37.65%和88.21%,平均增量分别为4.30、1.23 mg.结论 利用混合纤维和超细玻璃纤维滤膜采样的滤膜称重法测定工作场所空气中矿物油烟雾浓度是一种准确可靠、简单可行的方法.     

高效液相色谱法测定工作场所空气中对甲苯磺酸

目的 建立高效液相色谱法测定工作场所空气中对甲苯磺酸的方法.方法 利用浸渍超细玻璃纤维滤纸采集工作场所空气中气溶胶态以及蒸气态对甲苯磺酸,异丙醇-水洗脱,离子对高效液相色谱法测定.结果 方法检出限1.0μg/ml、定量下限为3.3μg/ml.测量范围0μg/ml～1 000μg/ml,相关系数(R2)大于0.999,其回归方程斜率(Mean±SD)为0.4821±0.0112.精密度:每张滤膜含100 μg、500 μg、2 500 μg对甲苯磺酸时,连续5d6次测定,其日内精密度(RSD)为1.9％～2.7％,日间精密度为2.3％ ～2.6％.实际样品加标回收率在91.6％～102.8％之间.超细玻璃纤维滤纸采集气溶胶态对甲苯磺酸的平均采样效率为95.7％、浸渍超细玻璃纤维滤纸采集蒸气态对甲苯磺酸的平均采样效率为95.2％.样品用异丙醇∶水(2∶98,V/V)洗脱,其洗脱效率大于97％.(浸渍)超细玻璃纤维滤纸采集对甲苯磺酸,在室温下至少可保存7d.结论 该方法具有较高的准确度、采样效率和解吸效率,较低的检出限,较好的精密度和稳定性,能满足了工作场所空气中对甲苯磺酸浓度的测定要求.     

Investigation of a dual filter sampling method for gaseous and particulate fluoride.

A two stage filter method designed to separate gaseous and particulate fluoride utilizing an alkaline treated filter to trap gaseous fluoride and post sampling heat treatment of the filters to promote desorption of gaseous fluoride from particulate phase was compared to standard impinger methods for the collection of hydrogen fluoride. Results indicate a high degree of comparability between the two methods. Initial studies involving the recovery of HF from dusted filters by heat treatment suggest recovery rates may vary directly with the amount of HF sampled for a given dust load.     

Residential formaldehyde sampling--current and recommended practices

The usefulness of test results in assessing the health hazard potential of residential formaldehyde exposures depends in great measure on the accuracy and reliability of sampling/analysis methods employed, the protocol used in collecting samples, sampling objectives, and an understanding of residential formaldehyde dynamics and their relationship to environmental variables. Active sampling and analysis methods including detector tubes, the impinger/chromotropic acid method, the impinger/pararosaniline method, and the CEA continuous monitor are reviewed as to advantages and limitations for residential sampling. Passive dosimeter methods including the Dupont Pro-Tec Badge, 3M Monitor, Air Quality Research, Inc. Passive Formaldehyde Kit, and Envirotech, Inc. Dosimeter are also reviewed. Sampling considerations for one-time formaldehyde sampling using the impinger/chromotropic acid method are discussed in detail, including pre-sampling closure of residences, maintenance of a standard indoor temperature both before and during sampling, the undesirability of sampling during cold, dry winter weather, sample number, sampling location, height and duration, environmental measurements during sampling, source identification and sample storage. A model formaldehyde sampling protocol based on the impinger/chromotropic acid method is described.     

Endotoxin,cat, and house dust mite allergens in electrostatic cloths and bedroom dust

Environmental exposure to endotoxin, Fel d I (cat) allergen and Der p I (house dust mite) allergen have been associated with asthma symptoms and have been measured in the environment using various sampling methods, including the electrostatic dust collector. The objectives of this study were to investigate whether levels of endotoxin and allergens were detectable in electrostatic dust collectors and to examine the correlation of allergen and endotoxin levels between electrostatic dust collectors and vacuum sampling methods (floor dust and mattress dust). Electrostatic cloths, bedroom floor dust and mattress dust samples from a subset of 60 homes were randomly selected from the Health of Occupants of Mouldy Homes study for allergen and endotoxin analysis. Fel d I and Der p I allergens were analyzed by double monoclonal antibody ELISA and endotoxin by the kinetic Limulus amoebocyte lysate assay. An enhanced ELISA method was used to analyze Der p I in the electrostatic cloths. Endotoxin was detected in all samples, however Fel d I and Der p I were not detected in all electrostatic dust collector samples (detection in 53% and 15% of cloths respectively). No correlations were found between cloth and dust samples for endotoxin or Der p I, but moderate-to-strong correlations were found between all three sampling methods for Fel d I (r_s = 0.612–0.715, p < 0.001). Poor correlation was found between floor dust and mattress dust samples for Der p I (r_s = 0.256, p = 0.048). Electrostatic dust collectors may provide a way to measure airborne dust and allergen. Given the moderate-to-low correlations with vacuum dust sampling, this may present a unique measurement system which, when collected alongside traditional vacuum dust sampling, could provide additional exposure measures. Further studies are required to correlate endotoxin and allergen levels measured by electrostatic dust collector with air sampling and to explore the relationships between these bioaerosols, environmental factors and asthma.     

Laboratory evaluation of silica gel sorbent tubes for sampling hydrogen fluoride

The NIOSH sampling and analytical method for inorganic acids employs a silica gel sorbent tube for the collection of five common inorganic acids with simultaneous determination of these acids in a single sample by ion chromatography. When the method was extended to the determination of hydrogen fluoride (HF) the sampled HF reacted with the silica gel and glass fiber of the sampler, but the reaction products remained trapped on the sorbent. Silica gel samplers were evaluated for the collection of HF from laboratory generated atmospheres. Factors tested included capacity, storage stability, humidity, accuracy and precision. Based on comparison with impinger collection, the mean recovery of HF from silica gel tube samples was 100.7% with a precision of 0.144.     

Field comparison of impingers and treated filters for sampling of total aliphatic isocyanates with the MAP reagent

Results of a comparative field study on the performance of 25-mm inhalable samplers (Institute of Occupational Medicine [IOM]) and midget impingers for the collection of total isocyanates in air using the 1-(9-anthracenylmethyl)piperazine (MAP) reagent are presented. Air sampling and analysis was performed according to the National Institute for Occupational Safety and Health MAP draft method 5525. Midget impingers filled with 15 mL of 1 x 10(-4) M MAP in butyl benzoate were operated at 1 L/min. IOM cassettes loaded with 25-mm quartz fiber filters impregnated with 500 microg MAP, were operated at 2 L/min. Filters were field extracted with 10 mL of 1 x 10(-4) M MAP in acetonitrile. Thirty-four impinger-IOM pairs were collected in three autobody shops during spray painting tasks. Regression analysis [Ln (IOM) = 1.0 Ln (impinger), R2 = 0.98] and a paired t-test (Pr > 0.9) demonstrated that impingers and IOMs perform equally in their collection efficiency for the monomer and total oligomeric hexamethylene diisocyanate (HDI). IOM performance did not deteriorate at longer sampling times compared with the impinger performance. Within-sampler variability was calculated from the individual coefficients of variation (CV) of the 17 pairs of like samplers. The mean of CVs (SD)% for the monomer and total oligomeric HDI was approximately 12 (12)% and 15 (13)% for the IOM and the impinger sampler, respectively. Poor correlation (Pearson correlation coefficient < 0.3) and statistically nonsignificant differences (P > 0.74 two-sided) were found for the between-sampler CVs. Factors that might have influenced the observed sampler agreement are also discussed. It is concluded that MAP impregnated filters can be successfully used for sampling of slow curing total aliphatic isocyanates in air.     

Ambient endotoxin concentrations in PM10 from Southern California

Concentrations of endotoxin in urban air pollution have not previously been extensively characterized. We measured 24-hr levels of PM10 (particulate matter < 10 microm in aerodynamic diameter) and the associated endotoxin component once every 6 weeks for 1 year in 13 communities in Southern California. All the samples collected had detectable PM10 and endotoxin levels. The geometric mean PM10 was 34.6 microg/m3 [geometric SD (GSD), 2.1; range, 3.0-135]. By volume, the endotoxin geometric mean was 0.44 endotoxin units (EU)/m3 (GSD, 3.1; range, 0.03-5.44). Per unit material collected, the geometric mean of endotoxin collected was 13.6 EU/mg (GSD, 3.2; range, 0.7-96.8). No correlation was found between endotoxin concentrations and other ambient pollutants concurrently measured [ozone, nitrogen dioxide, total acids, or PM2.5 (particulate matter < 2.5 micro m in aerodynamic diameter]. PM10 and endotoxin concentrations were significantly correlated, most strongly in summer. Samples collected in more rural and agricultural areas had lower PM10 and mid-range endotoxin levels. The high desert and mountain communities had lower PM10 levels but endotoxin levels comparable with or higher than the rural agricultural sites. By volume, endotoxin levels were highest at sites downwind of Los Angeles, California, which were also the locations of highest PM10. Endotoxin concentrations measured in this study were all < 5.5 EU/m3, which is lower than recognized thresholds for acute adverse health effects for occupational exposures but in the same range as indoor household concentrations. This study provides the first extensive characterization of endotoxin concentration across a large metropolitan area in relation to PM10 and other pollutant monitoring, and supports the need for studies of the role of endotoxin in childhood asthma in urban settings.     

工作场所空气中双酚A的高效液相色谱测定法

目的 建立工作场所空气中双酚A(BPA)的高效液相色谱测定方法.方法 通过玻璃纤维滤纸采集空气中气溶胶态的双酚A,乙腈洗脱后,高效液相色谱-荧光检测器测定.结果 该方法在0.01～10.00μg/ml范围中呈线性关系,检出限为0.005 μg/ml,最低检出浓度为3.3×10-5 mg/m3(以采集300 L空气样品计),平均加标回收率为97.5％～107.0％,相对标准偏差为2.5％～5.5％,洗脱效率为95.0％～101.9％,采样效率为99.6％,样品在室温下至少可保存7d.结论 方法各项指标均符合GBZ/T 210.4-2008《工作场所空气中化学物质测定方法》的要求,适用于工作场所空气中双酚A的检测.     

Efficiency and loading characteristics of EPA's high-temperature quartz fiber filter media.

It was experimentally demonstrated that Gelman Type A and "Microquartz" filters are efficient collectors of nonvolatile particles at high temperatures. Submicron particles penetrated more than large particles, and most at the highest filtration velocity tested of 51 cm/sec. In all tests, however, aerosol penetration was never more than about 0.10%. Nonvolatile particles penetrated less with increasing temperature filter loading. Particles with vaporization points below the sampling temperature, including H2SO4, can vaporize, pass through the glass fiber filters, and then recondense when cooled below their dew points. Therefore, the definition of "particulate matter" must be based upon a prescribed temperature. Hot stack gases, sampled at different filter temperatures, should not necessarily be comparable. Particulate emission standards must involve a suitable reference temperature to allow proper enforcement. Filtration efficiencies calculated by theoretical equations change dramatically with small changes in assumed average filter fiber diameter and/or particle size (or size distribution) used in the calculations. Pinholes not visible to the naked eye do not appear to effect penetration of glass fiber filters enough to significantly alter stack sampling results. Effect of temperature on filtration of non-volatile particles simply resulted in an increasing collection of submicron particles with increasing temperature. The main problems encountered at elevated temperatures were vaporization of volatile particles and mechanical leakage of the filter holder.     

Modeling evaporative loss of oil mist collected by sampling filters

Oil mists can cause respiratory distress and have been linked to skin and gastrointestinal cancers in workers. Standard concentration assessment methods call for sampling these mists with fibrous or membrane filters. Previous experimental studies using glass fiber (GF) filters and polyvinyl chloride and polytetrafluoroethylene membrane filters indicate that mist sampled onto filters may volatilize. A model has been developed to predict the evaporation of mist collected on a fibrous sampling filter. Evaporation of retained fluid from membrane filters can be modeled by treating the filter as though it is a fibrous filter. Predictions from the model exhibit good agreement with experimental results. At low mist concentrations, the model indicates that evaporation of retained mineral oil occurs readily. At high mist concentrations, significant evaporation from the filters is not expected because the vapor accompanying the airborne mist is already saturated with the compounds in the oil. The findings from this study indicate that sampling mineral oil mist with filters in accordance with standard methods can lead to estimates of worker exposure to oil mist that are too low.     

The recovery of smallpox virus from patients and their environment in a smallpox hospital

Attempts had been made in 1961 to recover smallpox virus by air sampling in smallpox wards and close to the mouths of smallpox patients, but these had been largely unsuccessful, possibly owing to the air sampling method used. Further attempts were therefore made in 1963, with a fluid impinger for air sampling and with Petri dishes placed below the orifice of the impinger to collect large droplets or particulate matter that the impinger might miss.     

Validation of transferability of DBA derivatization and LC-MS/MS determination method for isocyanates via an interlaboratory comparison

An adapted method for the quantitative determination of isocyanates in air was implemented and validated in-house. The method was based on air sampling using an impinger flask containing di-n-butylamine (DBA) in toluene and a glass fibre filter in series. The DBA derivatives were determined using liquid chromatography and tandem mass spectrometry. Studied isocyanates were isophorone diisocyanate, isocyanic acid (ICA), methyl isocyanate, ethyl isocyanate, propyl isocyanate, hexamethylene diisocyanate (HDI), 2,6- and 2,4-toluene diisocyanate, 4,4'-methylene diphenyl diisocyanate (MDI), phenyl isocyanate (PhI), MDI oligomers and different HDI adducts. Monitoring of selected reactions resulted in quantifications with correlation coefficients >0.995, within-batch relative standard deviation (RSD) of repeatability was <13% for all analytes. Between-batch RSD (reproducibility) was determined for all the compounds with the exception of the adducts and oligomers and was also <13%. As an additional validation procedure, the method was evaluated by exchanging field (air) and standard samples between two laboratories. The RSDs observed by the two laboratories were comparable. The concentrations determined were between 80 and 120% of each other, depending on the analyte and the individual concentrations. The method was applied in a large field study on exposure of workers in car repair shops and industrial painters with >500 samples.     

Within-home versus between-home variability of house dust endotoxin in a birth cohort

Endotoxin exposure has been proposed as an environmental determinant of allergen responses in children. To better understand the implications of using a single measurement of house dust endotoxin to characterize exposure in the first year of life, we evaluated room-specific within-home and between-home variability in dust endotoxin obtained from 470 households in Boston, Massachusetts. Homes were sampled up to two times over 5-11 months. We analyzed 1,287 dust samples from the kitchen, family room, and baby's bedroom for endotoxin. We fit a mixed-effects model to estimate mean levels and the variation of endotoxin between homes, between rooms, and between sampling times. Endotoxin ranged from 2 to 1,945 units per milligram of dust. Levels were highest during summer and lowest in the winter. Mean endotoxin levels varied significantly from room to room. Cross-sectionally, endotoxin was moderately correlated between family room and bedroom floor (r = 0.30), between family room and kitchen (r = 0.32), and between kitchen and bedroom (r = 0.42). Adjusting for season, the correlation of endotoxin levels within homes over time was 0.65 for both the bedroom and kitchen and 0.54 for the family room. The temporal within-home variance of endotoxin was lowest for bedroom floor samples and highest for kitchen samples. Between-home variance was lowest in the family room and highest for kitchen samples. Adjusting for season, within-home variation was less than between-home variation for all three rooms. These results suggest that room-to-room and home-to-home differences in endotoxin influence the total variability more than factors affecting endotoxin levels within a room over time.     

A comparison of the sampling efficiencies of a range of atmosphere samplers when collecting polymeric diphenylmethane di-isocyanate (MDI) aerosols

Polymeric diphenylmethane di-isocyanate (PMDI) is a precursor or an intermediate in the manufacture of pure MDI and is used in many industrial applications. Potential health effects of diisocyanates are generally considered to include irritation and respiratory sensitization, dictating the need for low occupational hygiene standards and robust hygiene monitoring methods. A wide range of methods has been developed or adopted for this purpose but questions concerning their ability to accurately sample MDI aerosols in the occupational environment have often been raised. In order to provide such information, studies have been conducted to compare several MDI sampling systems: the Institute of Occupational Medicine (IOM) 25-mm open-faced inhalable dust sampler; the 13-mm Millipore Swinnex Cassette sampler; the 37-mm open-face Millipore cassette; the midget-impinger, the glass tube containing glass wool, and two direct reading paper tape monitors. The program was comprised of two phases, the first being a preliminary comparison of the collection efficiencies of the IOM, 13 mm and midget-impinger at a range of orientations to air flow, aerosol particle sizes, and sampling flow rates, using inert polyethylene glycol aerosols. The second phase compared all samplers operating according to each manufacturer's recommendations and sampling PMDI aerosols at a range of particle sizes and concentrations. All studies were conducted in a wind tunnel. All filter methods performed well in atmospheres containing small particles except impingers that required a filter backup. In general, the variability of all the samplers was high for larger particle size ranges. Direct reading monitors showed low efficiencies.