Evaluation of the George Neal electrostatic precipitator

The Electric Power Research Institute (EPRI) is currently supporting a major research program characterizing the performance of high efficiency electrostatic precipitators (ESP). One such effort evaluating the George Neal ESP of Iowa Public Service Company is described in this paper.Results show that under well tuned conditions the ESP overall collection efficiency was 99.7% at a specific collecting area of 745 ft²/kacfm (147 m²/m³/s) (520 MW) with associated mass concentrations of 0.025 lb/10⁶ Btu and stack opacity of 4.6%. The boiler outlet size distribution was found to be bimodal with submicron and large particle peaks at 0.2 and 5 microns diameter, respectively. Consequently, an apparent bimodal fractional efficiency curve results with efficiencies of 99.6%, 98%, and 90% measured for 20, 2 and 0.2 micron diameter particles, respectively. Rapping reentrainment losses were found to be insignificant except during episodes of high ash hopper levels resulting from a malfunctioning ash removal system, when large rapping puffs were observed. In addition, outlet emissions increased dramatically to 0.08 lb/10⁶ Btu (34 ng/J) during these periods, suggesting that an emission level more representative of daily operation lies somewhere between 0.025–0.08 lb/10⁶ Btu (10.8–34 ng/J).     

Experimental measurements of aerosol concentrations in offices

A new automated version of the piezoelectric microbalance measures the mass concentration of airborne particles smaller than a preselected aerodynamic cutoff diameter. It is designed for near-real-time, unattended, round-the-clock measurements of nearly any aerosol environment inhabited by humans. The instrument uses an electrostatic precipitator to deposit particles with greater than 95% efficiency onto a piezoelectric quartz crystal sensor which is able to detect a deposit of 0.005 μg. The precipitator and sensor are nearly identical to those in the portable instrument reported previously. Measurements comparing within ± 15% with gravimetrically measured filter samples are documented for a wide variety of aerosols in the 50 μg/m³ to 5.5 mg/m³ range. The instrument measures particles from 10 μm down to 0.01 μm in diameter, including submicron combustion smokes and metallic fumes. The piezoelectric microbalance technique senses the mass concentration of the aerosol, rather than light scattering properties as is done by photometers and nephelometers. The piezobalance, with 1 L/min sample flow, is more sensitive than any other mass-sensing instrument, making it especially suited for low concentration indoor measurements, even below 50 μg/m³. An automatic piezobalance recently measured respirable aerosol mass concentrations in several offices. Each measurement was the average concentration during a 30-min period. The 24-h/day measurements continued for several days. Especially interesting is the diurnal pattern, both for offices with and without smokers. The effect of a single nearby smoker was clearly illustrated when the smoker was absent one day in the middle of a week. Normal daytime peak concentrations in that office reached 80–110 μg/m³ with a smoker present, but only 50–60 μg/m³ when the smoker was absent. Curious smokers who briefly stopped byt o see the instrument caused single half-hour averages to triple, to values as high as 294 μg/m³ in one office.     

Aerosol filtration by a cocurrent moving granular bed: Penetration mechanisms

An experimental apparatus has been constructed to investigate aerosol filtration by a cocurrent moving granular bed filter (CMGBF). In a CMGBF, aerosol passes downward through a descending bed of dirty granules while clean granules are added continously at the bed top. The effect of an intergranular dust deposit on penetration in a CMGBF was investigated in a 2⁴ factorial experiment in which the control variables were superficial gas velocity (100 and 250 mm/s), bed depth (130 and 230 mm), granule size (2.1 and 2.7 mm), and the intergranular dust deposit expressed as percent by weight of collected dust in the bed (1% and 5%). All tests were conducted at ambient temperature and pressure using resuspended utility boiler fly ash as the test aerosol.Mass penetration data identified two major penetration mechanisms: (1) straight through penetration and (2) reentrainment due to granular motion. A static, intergranular dust deposit produced high filtration efficiency (>99%) at the low superficial velocity. When the bed was moving, reentrainment of collected dust was significant and accounted for about three-quarters of the penetrating dust. Particle size analyses reveal that the two penetration mechanisms are size dependent. Most particles larger than about one micrometer in diameter that penetrate the CMGBF do so by reentrainment after being collected initially. Virtually no particles smaller than about 0.3 μm in diameter penetrate by reentrainment; when these small particles penetrate, they pass straight through without being collected.     

Introduction to and experimental conditions during the first year of the GMR chronic inhalation studies of diesel exhaust

A chronic exposure study was initiated to determine the effects of diesel exhaust on the health of experimental animals. For this purpose, test atmospheres of clean air (control) or freshly diluted diesel exhaust at concentrations of 250, 750, and 1500 μg/m³ were supplied to four 12.6 m³ inhalation chambers which housed rats and guinea pigs. Diesel aerosol size and concentration, as well as chamber temperature and relative humidity, were continually monitored and controlled to maintain the exposure dose levels and an environment of 22±2°C and 50%±20% relative humidity. The concentrations of CO and NO_x were found to be 5.8±1.0 mg/m³ and 7.9±1.0 mg/m³ above ambient in the chamber containing 1500 μg/m³ of particulate. Animals were supplied from the chambers, on a random basis, for both intramural and extramural studies throughout the exposure period. The experiment ran uninterrupted for over twelve months with mean diesel particle mass concentrations within 2% of the target values.     

Air infiltration measurements in a home using a convenient perfluorocarbon tracer technique

Using miniature perfluorocarbon tracer (PFT) sources and miniature passive samplers, both about the size of a cigarette, tests conducted in the laboratory and in a typical home successfully demonstrated the utility of the PFT kit as a means for implementing wide-scale infiltration measurements in homes. The PFT diffusion plug source, an elastomer containing a dissolved perfluorocarbon compound, was shown to emit vapors at the rate of about 0.1 to 5 nL/min, providing steady-state concentrations in a home of about 1 to 10 pL/L, i.e., parts per trillion by volume, when one source is deployed for each 300–500 ft² (28–46 m²) of living space. The emission rate from the diffusion source was predictable, but its dependence on both temperature and time suggested the development of alternative approaches. One such alternative, a liquid PFT permeation source, had emission rates which could be tailored over the range 10–20 nL/min, were independent of age for as long as the liquid remained ( 5 yr), and had significantly lower temperature dependence. A number of passive adsorption tube samplers performed reproducibly and identically (to within ±2%–3%) in laboratory tests. Together with a programmable tracer sampler, the miniature diffusion sources and samplers were deployed in a typical home; six PFT sources were uniformly deployed, three on each level of a two-story house. Multiple location sampling, as well as sampling in rooms with and without a miniature source, demonstrated that even in a house without forced-air circulation, a well-mixed modeling approach is justified. Analyses of the tracer samplers were performed back in the laboratory with an automatic electron-capture gas-chromatography system. The effects of the inside/outside temperature differential, as well as that of an open fireplace compared with a wood-burning stove, on the measured air infiltration rates were clearly demonstrated. Comparisons of the PFT tracer method with that of the SF₆ tracer decay approach showed the results of the two methods to be identical within experimental precision. With this miniature source and sampling tracer kit, infiltration rates in the range 0.2–5 air changes per hour can be measured over time-averaged periods of as little as 1 day up to several years.     

Plutonium isotopes in surface air of Prague in 1986–2006

Monitoring of ^239,240Pu in surface air of Prague started in 1986 in connection with the Chernobyl accident. Measurable activities of 10–28 μBq m⁻³ were found from 29 April 1986 to 5 May 1986. In the most of the monitoring periods of 1987–1996, activities of ^239,240Pu in air were not measurable. Positive values for ^239,240Pu and ²³⁸Pu in air could be obtained after installation of an aerosol sampler with higher flow-rate in 1997. Activity concentrations of ^239,240Pu and ²³⁸Pu in Prague air in the most of quarters of 1997–2006 were in the range 0.53–5.06 and <0.16–1.10 nBq m⁻³, respectively. Seasonal fluctuations can be found in content of ^239,240Pu in air. Activity ratios of ²³⁸Pu/^239,240Pu in air are higher than those in top soil, so it can be supposed that ²³⁸Pu is coming to air of Prague also from other sources than resuspension of fallout from atmospheric nuclear tests.     

Physical characterization of diesel exhaust particles in exposure chambers

Since the deposition of particulate in the respiratory system is strongly influenced by particle size, a correct assessment of this parameter is important for any inhalation experiment studying the potential health effects of air pollutants. Measuring the distribution of particles according to their aerodynamic diameter and mechanical mobility diameter is crucial in analyzing the deposition of submicron particles in the lower respiratory system. Cascade impactor measurements of diluted diesel exhaust in 12.6 m³ animal exposure chambers in the GMR Biomedical Science Department showed that the mass median aerodynamic diameter of the aerosol was 0.2 μm with 88% of the mass in particles smaller than 1 μm. Diffusion battery measurements showed that the mass median mechanical mobility diameter was about 0.11 μm. Transmission electron micrographs of particles deposited on chamber surfaces revealed both agglomerates and nearly spherical particles. The particles in these chambers are similar in size and shape to diesel particles described elsewhere. The flux of diesel particles to food surfaces was measured. Calculations of the expected daily dose by inhalation and by feeding showed that the “worst case” dose by feeding was only about one-tenth the dose by breathing.     

Contribution of tobacco smoke to environmental benzene exposure in Germany

The concentrations of environmental tobacco smoke (ETS) constituents including benzene were measured in the living rooms of 10 nonsmoking households and 20 households with at least one smoker situated in the city and suburbs of Munich. In the city, the median benzene levels during the evening, when all household members were at home, were 8.1 and 10.4 μg/m³ in nonsmoking and smoking homes, respectively. The corresponding levels of 3.5 and 4.6 μg/m³ were considerably lower in the suburbs. Median time-integrated 1-week benzene concentrations in the city were 10.6 μg/m³ in nonsmoking homes and 13.1 μg/m³ in smoking homes. In the suburbs, the corresponding values were 3.2 and 5.6 μg/m³. While the benzene concentrations in nonsmoking homes located in the city were significantly higher (p < 0.05) than in suburban nonsmoking households, no difference was found between smoking and nonsmoking households located either in the city or in the suburbs. Individual exposures to benzene and to specific markers for tobacco smoke of all household members (82 nonsmokers and 32 smokers) were determined by questionnaire, personal monitoring, and biomonitoring. Within the city, the benzene exposure determined by personal samplers was 11.8 μg/m³ for nonsmokers living in nonsmoking homes and 13.3 μg/m³ for nonsmokers in smoking homes. The corresponding values for nonsmokers living in the suburbs were 5.9 and 6.9 μg/m³, respectively. Neither difference was statistically significant. Nonsmokers living in nonsmoking households in the city had significantly higher exposure to benzene compared to their counterparts living in the suburbs (personal samplers: 11.8 vs 5.9 μg/m³, p < 0.001; benzene in exhalate: 2.4 vs. 1.1 μg/m³, p < 0.05; trans,trans-muconic acid excretion in urine: 92 vs. 54 μg/g creatinine, p < 0.05). Nonsmokers from all households with smokers were significantly more exposed to benzene than nonsmokers living in the nonsmoking households (personal samplers: 13.2 vs. 7.0 μg/m³, p < 0.05; benzene in exhalate: 2.6 vs. 1.8 μg/m³, p < 0.01; trans,trans-muconic acid excretion in urine: 73 vs. 62 μg/g creatinine), but the contribution of ETS to the total benzene exposure was relatively low compared to that from other sources. Analysis of variance showed that at most 15% of the benzene exposure of nonsmokers living in smoking homes was attributable to ETS. For nonsmokers living in nonsmoking households benzene exposure from ETS was insignificant.     

Microbial extracellular enzyme activities in Humex Lake Skjervatjern

Two microbial extracellular enzyme activities (MEEA) were studied in HUMEX Lake Skjervatjern: acid phosphatase (APHA) and leucine aminopeptidase (LeuAMPA). Both enzyme activities varied in the vertical and horizontal scale in both lake sites. APHA varied in the acidfied Basin A between 945–1706 nmol L⁻¹ h⁻¹ and LeuAMPA between 3.7–25 nmol L⁻¹ h⁻¹. Both MEEA reached maxima in 0.5 m depth. In the control site (Basin B), APHA was lower by a factor of two, and varied between 156–669 nmol L⁻¹ h⁻¹. LeuAMPA reached similar values as in Basin A and varied between 7.8–34.8 nmol L⁻¹ h⁻¹. Maxima of APHA were found in the upper layer (0–2 m), while LeuAMPA had only one distinct maxima at 2–2.5 m depth. The number of bacteria (AFDC) varied between 4.4–8.8 10⁶ cells mL⁻¹ and was not significantly different in either side, but both had maxima in the thermocline. Highest specific LeuAMPA activities were found in the thermocline (3.2–4.5 fmol L⁻¹ h⁻¹ cell⁻¹) in both sides and varied between 0.4–4.5 fmol L⁻¹ h⁻¹ cell⁻¹ in both water columns. The main contributor (60–70%) to LeuAMPA was found in the microplankton fraction, retained on Nuclepore filters with pore sizes between 2.0-0.2 μm. APHA was retained less even on a filter with pore size smaller than 0.2 μm. About 50–70% of APHA passed through 0.2 μm-0.1 μm Nuclepore filters and could be found in the dissolved organic matter (DOM) fraction. APHA and bacteria counts (AFDC) showed a distinct gradient from the littoral zone to the pelagial in the surface water samples (0.2 m depth). APHA and LeuAMPA are regarded as important regulators for nutrient availability to microplankton. However, all data from vertical as important regulators for nutrient availability to microplankton. However, all data from vertical and horizontal samples showed that Lake Skjervatjern is a strongly gradient-dominated aquatic ecosystem. Watershed-littoral effects are more pronounced in the shallow, acidified Basin A than in the control side, Basin B.     

Evaluation of selected monitoring methods for formaldehyde in domestic environments

Varioys analytical methodologies for the monitoring of formaldehyde (CH₂O) concentrations in domestic environments have been developed and evaluated. A modified CEA Instruments, Inc., analyzer has near-real-time CH₃O-specific analysis capability with an 0.01 mg/m³ detection limit. A solid sorbent, 13X molecular sieve has been utilized in a pumped collection unit with a demonstrated 0.03–12.5 mg/m³ linear dynamic range using sampling periods of ≤ 15 min. The development of screening-type techniques has included (1) a semipermeable-membrane passive sampler for measurements of average CH₂O concentrations over 8–24-h periods, and (2) a visual colorimetric analysis method for semiquantitative CH₂O determinations using solid chemical reagents. A preliminary field evaluation has been completed. The results show excellent agreement between the new CH₂O monitoring methods and a reference sampling and analysis technique. A generation apparatus for the production of CH₂O vapor is also reported with a demonstrated linear dynamic range between 0.003 and 12.5 mg/m³.     

Odor-annoyance estimates from roadtraffic combustion exhausts: Calibration with master scaling using pyridine as a reference

The present field study addressed the need for a procedure that provides a defined unit of measurement of perceived annoyance from environmental odors, calibrating the estimates for individual scaling behavior and context effects. In including 25 subjects, the purpose was to demonstrate the applicability of the master-scale procedure with magnitude estimation to perform such a calibration of odor-annoyance estimates for target stimuli such as road-traffic combustion exhausts (13 000 vehicles/d; averaging 47 μg/m³ over the day/night with peaks exceeding 100 μg/m³ of nitrogen dioxide; NO₂). For comparison, calibrated estimates were also obtained for a backyard expected to be considerably less polluted (comparable with 18 μg/m³ of NO₂) and for blank stimuli presented indoors. The data transformation for the calibration procedure with which annoyance is expressed in either master-scale units or pyridine equivalents requires estimates of a reference stimulus for which seven concentrations of pyridine were used. The results provide an illustration of master scaling of odor annoyance, and imply that use of a modulus (standard stimulus with a predefined annoyance magnitude), in contrast to master scaling, is not sufficient for calibration for individual scaling behavior and context effects.     

Particulate collection in a high temperature cyclone

A new particle collection technique is analyzed and presented for its potential application in a high temperature, high pressure gas cleaning system. The technique is based on the collision and the aglomeration phenomena among the coal-ash particles when the cyclone is operated near the coal-ash fusion temperature. The percent increase of agglomeration rate is estimated by mathematical modeling for particles smaller than five microns in diameter. Particulate collection efficiency with or without agglomeration is presented. Experimental results in a high temperature cyclone are presented. The output dust loading varied from 0.025 to 5 grains per cubic foot (0.057–11 g/m³) as the input dust loading is increased from 4 to 35 grains per cubic foot (9.2–80g/m³) of gas flow.     

Composition and Some Ecological Features of Winter Zooplankton in Deep Stratified Lakes

For the first time, zooplankton and environmental factors have been studied in winter in the deep stratified lakes Siverskoe, Borodaevskoe, and Vydogoshch. The zooplankton consists of 18–22 species of rotifers, copepods, and cladocerans, including 15–18 specifically winter, cryophilic and eurythermic forms. The populations of zooplankters reproduce actively: males and egg-bearing females (in copepods), females with embryos and eggs in brood pouches (in cladocerans), and females with attached eggs (in rotifers) are present. In lakes Siverskoe and Borodaevskoe (depth 20–24 m), where oxygen deficiency is observed only in the bottom water layer, the zooplankton populates the greater part of the water column and forms a large aggregation in the oxycline and near the bottom. The abundance of bacteria in these zones is high (up to 4–6 × 10⁶ cells/ml). In Lake Vydogoshch (depth 16 m), oxygen deficiency extends to the middle layers, and all zooplankton is distributed above the oxycline. The biomass of winter zooplankton in Lake Siverskoe in 1983 averaged 1.26 g/m³, with a maximum of 4 g/m³; in 1993, 1.4 and 8.04 g/m²; the respective values in Lake Borodaevskoe were 0.98 and 3.1 in 1983 and 0.14 and 1.6 in 1993; in Lake Vydogoshch, 0.15 and 0.24 in 1983 and 1.25 g/m³ in 1993. The development of winter zooplankton is limited by the size of the zone of oxygen deficiency and depends on the amount of food (bacterioplankton). The distribution of zooplankton in the water column and its biomass in individual layers is determined by the rate of methane formation and oxidation.__________Translated from Ekologiya, No. 3, 2005, pp. 201–214.Original Russian Text Copyright © 2005 by Rivier.     

Dynamic simulation of a decentralized polygeneration plant providing SNG,steam and power

The behaviour of a decentralized polygeneration plant providing synthetic natural gas (SNG), steam and electrical power is simulated in three scenarios in this study. The plant size is based on an assumed capacity of decentralized polygeneration plants processing 1070 m³ h^?1 (STP) of syngas. 396 m³ h^?1 (STP) of raw SNG, 0.4 t h^?1 of steam at 5 bar and 670 kW of electrical power can be generated by the plant at the reference scenario. Methanation reactor and steam generator are modelled in detail. Further results indicate that such a polygeneration plant can provide positive and negative operation reserves for the electricity network to the extent of 100% of the reference power output, while the amount of generated steam varies by less than 40%. At the same time, the generated SNG quality keeps constant. Lower variations in the amount of generated steam are applicable when reducing the operation reserve capacity.     

Heterotrophic Nano- and Microplankton under Conditions of Anthropogenic Eutrophication of the Bay of Novorossiisk

Seasonal and long-term dynamics of heterotrophic plankton in the Bay of Novorossiisk are discussed. It is shown that specific variation in the biomass of nanoheterotrophs and infusoria is associated with the processes of anthropogenic water eutrophication. The biomass of infusoria has increased ten times and that of zooflagellates two times since 1985–1986. Infusoria of the genera Strombidium, Strobilidium, and Mesodiniumare dominant in the protozoan plankton. The annual average level of Oligotrichadevelopment in the bay is characteristic of eutrophic water bodies (112–417 mg/m³); in the spring–summer season, however, it may increase to 500–1034 mg/m³. In the part of the bay near the port, which is exposed to a strong anthropogenic impact, the biomass of ciliate protozoa can reach 2 g/m³.     

Fallout in the New York metropolitan area following the chernobyl accident

In the metropolitan New York area, maximum concentrations in air of radioactive aerosol and gaseous debris from the Chernobyl accident of April 1986 were much lower than those measured in Europe. The observed maxima were: for gaseous ¹³¹I, 23mBq m⁻³; for aerosol samples, 20mBq m⁻³ of ¹³¹I and 9·mBq m⁻³ of ¹³⁷Cs. The data suggest that little gas-to-particle transformation of iodine occurred during transport of the radioactive cloud from the Ukraine to New York. The ratios of ¹⁰³Ru and other refractories to ¹³⁷Cs were low in the first debris sampled, debris which probably was emitted from Chernobyl in late April during the early stages of the accident. In subsequent samples these ratios were higher, presumably because debris from the later, hotter stages of the fire had reached our sampling sites. A significant fraction (25–40%) of the deposition of ¹³¹I and ¹³⁷Cs into our samplers and on grass was by dry deposition. The total deposition of Chernobyl ¹³⁷Cs in the area was <1% of that already present in the soil from fallout from past nuclear weapon tests. The highest concentration of ¹³¹I measured in fresh milk was about 1.5 B1 liter⁻¹, <0.1% of the US action level. The dose to the thyroid of a six-month-old infant who had fresh milk as a sole food source would be about 70 μGy (7 mrad).     

Impact of climatic conditions on irrigation water requirements and hydraulic characteristics of modern irrigation systems

Irrigation system performance regards as a function of climatic conditions. The present study was carried out to study this phenomenon. Sugar beet and sesame corps were cultivated during two agricultural seasons of 2017/2018 and 2018/2019 irrigated with drip and sprinkler systems. The drip and sprinkler systems performance was evaluated in terms of hydraulic characteristics added to irrigation water requirements. The recorded monthly values were compared to the traditional estimation method. The results revealed that irrigation system efficiency was increased by increasing ambient temperature for the drip irrigation system, and vice versa was noticed with the sprinkler irrigation system. Emission uniformity and application efficiency of emitters were increased by increasing ambient temperature. While the sprinkler flow rate and distribution uniformity were decreased by increasing ambient temperature. For drip irrigation system, the average total amount of irrigation water requirements using traditional estimation for sugar beet (2372 m³/fed) was less than the actual calculated (2439 m³/fed), while for sesame crop, the traditional estimation method (2556 m³/fed) was higher than actual calculated (2477 m³/fed). Using a sprinkler system, the average total amount of irrigation water requirements by the traditional estimation (2689 and 2897 m³/fed) was less than the actual calculated (2709 and 3044 m³/fed) for sugar beet and sesame crops, respectively. So, it is important to consider the effects of climatic conditions through the agricultural season.

     

The genotoxic contribution of wood smoke to indoor respirable suspended particles

The effect of wood burning stoves on the genotoxicity of indoor respirable organic matter was investigated for four homes during the winter and spring of 1986. Paired samples, one collected when the stove was not used and one when wood was burned, were extracted with dichloromethane and acetone. Aliquots of the dichloromethane extracts were analyzed with and without metabolic activation using the Microscreen bioassay. The Microscreen is a rapid, sensitive bioassay which measures a broad genotoxic endpoint, λ-prophage induction. Per nanogram of organic material, wood smoke proved to be a major source of indirect (observed with metabolic activation) but not direct genotoxins in homes. The increase in indirect genotoxicity for extracts from aerosol containing wood smoke is probably due to higher concentrations of polycyclic aromatic hydrocarbons in the wood smoke aerosol as well as other unidentified classes. The direct genotoxicity observed for extracts of aerosol not containing wood smoke decreased with metabolic activation. This direct genotoxicity may be related to cooking activities in the homes. The trends in genotoxicity observed per nanogram of organic material are more pronounced when expressed per m³ of air due to the higher percentage of extractable material in aerosol containing wood smoke.     

Collection characteristics of a double stage scrubber to eliminate the paint mist from a spray booth

A 4.5 m³/min laboratory paint spray booth was built adopting a double-stage scrubber with heavy oil as the scrubbing liquid. The relationship between the collection efficiency E and the pressure drop ΔP was studied using a cylindrical paper tilter and a Digital Dust Counter. Experimental results indicated that the collection efficiency in this system is in accordance with the collection efficiency equation based on the theory of inertial impaction. With water used as the scrubbing liquid, the factor K is about 0.5 for single-stage scrubbing, while it is 0.6 for double-stage scrubbing. At a pressure drop of 60 mm of H₂O, heavy oil used as the scrubbing liquid gained about 2.0% more in collection efficiency than water. The zigzag baffler equipped for removing heavy oil mist was also effective for the paint mist collector, and 99.1% of E was gained at a pressure drop of 135 mm H₂O.     

Development of a personal exposure monitor for two sizes of inhalable particulates

Measurement of personal exposure to ambient level particulate concentrations is often extremely difficult because of a lack of personal exposure monitors capable of collecting measurable quantities within a meaningful sampling period. A new personal exposure monitor for two fractions of inhalable particulates (i.e., the 3–15 μm aerodynamic diameter and the < 3 μm or respirable fraction) has been developed and characterized. This monitor is capable of collecting a sample of each fraction that is quantifiable with ambient concentrations of inhalable/respirable particulates as low as 25 μg/m³ in a 24-h sampling period. Wind tunnel tests have been made on the particulate personal exposure monitor to determine sampling efficiency as a function of relative wind speed and orientation with respect to the sampler.