Air Filter Samples Research Articles

Downwind Residue From Air Spraying Of A Dwarf Apple Orchard

ABSTRACT The edge row of dwarf apple trees was sprayed with an air sprayer; fluorescent dye was used to trace spray drift deposits. Tracer deposited on the ground was measured with plastic collectors and airborne spray was captured and measured with string, bottle, and high-volume, air-sampling filter collectors. Microclimatic variables including vertical heat flux were measured. Ground deposit decreased greatly beyond 120 m; about 0.03% of total material sprayed was deposited between 122 and 152 m downwind. Airborne spray between the ground and a 20 m level at 122 m downwind was estimated to be about 3.5%. Ground collectors and an unobstructed array of string collectors located 5.0 m from the sprayer captured about 75% of the total material sprayed.

Measurement of the Alkalinity of Filter Media

Alkalinity can affect the performance of air sampling filters because alkaline sites on the filter can react with SO2, HNO3, and other acid gases to form sulfates and nitrates. These sulfates and nitrates cannot be distinguished from participate sulfate and nitrate collected by the filters. In turn, the total particulate weight, sulfate content, and nitrate content determined are falsely high In proportion to filter alkalinity. Thus, alkalinities of older filters have been measured to determine appropriate correction factors for previously obtained particulate data. Alkalinity of new filters is also tested for compliance with procurement specifications. At laboratories measuring alkalinity, a reproduclbillty problem has been observed In using ASTM Method D 202, which was Intended for analysis of electrical insulating paper and not glass fiber or quartz fiber media. Therefore, we investigated the factors Influencing alkalinity measurements and developed a simple, reproducible method of analysis. The result...

Determination by Atomic Spectrometry of Chromium on Air Sampling Filters in the Presence of Iron

A simple, sensitive and accurate method for quantifying chromium collected on air sampling filters in the presence of iron is reported. This procedure, based on inductively coupled plasma atomic emission spectrometry (ICP-AES), eliminates the need for chemical agents which are necessary to minimize the suppressive interference from iron in flame-atomic absorption spectrophotometry (flame-AAS). The extent of this interference in flame-AAS is illustrated, and the development of the ICP-AES technique is described. The spectral background of the analytical wavelength for chromium at 267.72 nm was examined. The linear analytical range was from 0.1 µg to 5.0 mg in 20.0 mL solution. The recovery at 0.5 µg to 100.0 µg in the presence of 0.5 µg to 3.0 mg of iron was from 87% to 102%. When air sampling filters collected at welding sites were analyzed for trace levels of chromium, the accuracy of this method was demonstrated despite the presence of up to 2 mg of iron.

Determination by Atomic Spectrometry of Chromium on Air Sampling Filters in the Presence of Iron

Determination by Atomic Spectrometry of Chromium on Air Sampling Filters in the Presence of Iron

Occupational allergy to locusts: An investigation of the sources of the allergen

Allergic symptoms occur commonly in subjects working closely with locusts and are associated with specific IgE antibody. Extracts of intact locusts ( Schistocerca gregaria and Locusta migratoria) were used to identify specific IgE antibody, to define the major allergens of the locust and their sources, and to estimate aeroallergen concentration in the working environment. With questionnaire, skin prick tests, and specific IgE measurements, 35 individuals, working in a research center, were surveyed. Of the 15 currently exposed individuals, contact with locusts provoked asthma, rhinitis, and contact urticaria in five, rhinitis and urticaria in three, and rhinitis alone in one individual. Symptoms provoked by locusts and skin test reactions to locust extracts were associated with specific IgE antibody in the serum. The “immunoblot” technique demonstrated the presence of multiple allergens in the locust extracts of approximately 68, 66, 54, 43, 37, 29, and 18 K daltons molecular weight. Locust antigen was identified in the atmosphere by means of an immunochemical method involving elution of high-volume air-sampler filters exposed in the locust breeding room and analysis of eluate allergen content by RAST-inhibition assays. Logit transformation of RAST-inhibition lines demonstrated that the filter extract shared a common slope with the locust extract and with an extract of locust gut. This gut extract also shared a common slope with extracts of locust feces and peritrophic membrane. The major source of allergen appears to be the peritrophic membrane that is present in the gut and is excreted surrounding the feces.

Allergy to rats: Quantitative immunoelectrophoretic studies of rat dust as a source of inhalant allergen

The antigenic composition of an extract of rat dust, as a source of aeroallergens for rat-sensitive individuals, has been investigated and compared to the antigenic composition of rat saliva and urine. Of four main antigenic peaks identified by crossed immunoelectrophoresis, one antigenic peak (Ag 4) was demonstrated to be antigenically closely related to and with similar molecular weight (approximately 22 kd) and isoelectric point values as urinary prealbumin, already recognized as a major rat allergen. Ag 4 was present in all dusts studied and was also identified as a minor component of saliva. However, no component with the same electrophoretic mobility or physicochemical characteristics of the α 2-euglobulin of male rat urine that shares partial identity with the prealbumin was detected, even in dust collected from a male rat room. A second high molecular weight (>200 kd) component, Ag 1, present in most of the dust extracts, could not be detected in either urine or saliva. Crossed immunoelectrophoresis and skin prick tests confirmed the allergenicity of both these antigens. Analysis of an air filter sample taken within a male rat room revealed significant amounts of the “prealbumin” component, and a monospecific antiserum to this component was used to quantitate levels in dusts collected from various locations. These findings suggest that a major inhalant allergen present in rat dust is closely related to urinary prealbumin but that this and other allergenic components may not be derived predominantly from rat urine or saliva but possibly from secretions originating from the skin of the animals and present in the fur.

Sources of atmospheric trace metals over the subtropical North Atlantic

Air filter samples were taken over the subtropical North Atlantic under the temporary influence of a Saharan dust plume. Analyses for trace metals showed that most of the determined elements (Al, Sc, Cr, Fe, Co, Zn, Cs, La, Ce, Sm, and Th) were predominantly of crustal origin. Additionally, for Mn and Se a significant marine contribution could be detected.

Liquid scintillation counting of 55Fe applied to air-filter samples.

A simple and rapid method has been improved for determination of low specific activity of 55Fe with a liquid scintillation counter. High counting efficiency was obtained for a sample containing up to 150 mg of iron using mixture of a colorless solution of phosphate iron complex and an emulsifier liquid scintillator. The detection limit was 0.31 Bq (8.4 pCi) per gram iron assuming the counting for 1000 minutes and 95% confidence level. This counting method was applied to determination of 55Fe in air-filter samples.

Guinea-pig-derived allergens. Clinicoimmunologic studies, characterization, airborne quantitation, and size distribution.

Of 20 serum samples from laboratory workers who experienced allergic symptoms after exposure to laboratory animals, 9 contained elevated IgE antibodies to guinea pig urine, pelt, or albumin by the radioallergosorbent test (RAST). Skin testing documented allergenic activity with all 3 guinea pig allergens. The cross-reactivity of these 3 guinea pig allergens was studied in RAST inhibition assays. Guinea pig pelt extract and urine produced dose-related inhibition in all 3 assays, but guinea pig albumin was inhibitory in only the homologous assay. Characterization by gel filtration, polyacrylamide gel electrophoresis, and isoelectric focusing demonstrated heterogeneity of the allergens. Air filter samples were taken in a guinea pig housing room, a research laboratory, and a library, using a high volume air sampler. An outdoor air filter sample was also taken. Guinea pig urine allergen activity was detected in all indoor air filter samples by RAST inhibition. Guinea pig pelt allergen activity was detected in all air filter samples, except the library and outdoors. Guinea pig albumin was not detected in any air filter sample. Sizing of airborne particles demonstrated that most guinea pig allergen activity was associated with particles of a diameter greater than 5 mu and less than 0.8 mu. Urine appears to be the major source of guinea pig allergens, and it is present in airborne particles small enough to penetrate the lower respiratory tract when inhaled.

Radioactivity in environmental samples: Calibration standards measurement methods, quality assurance, and data analysis

The numerous environmental radioactivity measurements made by and for the U.S. Environmental Protection Agency (U.S. EPA) include measurements on samples of water, urine, food, milk, and air filters. Calibration standards are listed which are available in the form of water solutions and soils for a wide range of radionuclides. Method validation procedures for U.S. EPA approval include protocol development and single-laboratory and multiple-laboratory evaluation for precision and accuracy. Interlaboratory comparison studies are conducted for both cross-check and performance evaluation samples and involve 295 federal, state, and local laboratories. For water samples, 80%–90% of the participating laboratories are within the control limits for most of the radionuclides measured; however, some problem areas exist, especially for radium-228 and strontium-89 and -90. For milk and food samples, more than 90% of the laboratories are within control limits for cobalt-60 and cesium-137 but some problems exist for the measurement of strontium-90, iodine-131, and potassium-40. For tritium, 91% of the laboratories are within the control limit for water samples and 87% are within the control limits for the urine samples. The laboratory performance for air filter samples shows some problems for gross beta, strontium-90 and cesium-137 measurements.

Measurement of Potential Alpha Energy Concentration of Radon and Thoron Daughters Using an Electret Dosemeter

An electret dosemeter consisting of an electret loaded into a 60 ml chamber has been used earlier for quantitative measurement of gamma radiation. The chamber was modified to hold an air sampling filter paper at the bottom and air was sampled through it. It was shown that nearly 20% of the energy of alpha radiation emitting from the filter paper was dissipated in the volume of the chamber. This energy in turn produced ion pairs which were collected by the electret resulting in a measurable change in charge status of the electret. By taking an air sample of known volume and allowing the registration of alpha energy, not only during sampling but also for three hours after sampling, a direct measure of the potential alpha energy concentration of radon daughters could be calculated in easily interpretable working level units. By proper choice of the thickness of the electret and the total flow, it was possible to measure radon daughter concentrations down to milliworking level units. The field measurements carried out by this method compared well with those obtained by established methods. The procedure was particularly useful for measuring time-averaged concentrations needed for effective survey of a mine area or for personal dosimetry. For thoron decay products, it was shown that the alpha energy concentration measured during sampling and up to a period of 7.7 hours post sampling, time being reckoned from the mid-time of sampling, yielded 33% of the potential alpha energy concentration due to thoron daughters. An air sample collected and measured in this way registered all of radon daughter alpha potential energy and one third of thoron daughter alpha potential energy, thus providing an equivalent radon daughter concentration. This procedure is suitable for evaluating any mixture of daughter products without consideration of whether they originated from radon or thoron.

Use of 206Pb/ 204Pb isotope ratio in lichen, air filter, incinerator ash and gasoline samples as pollution source indicator

The stable lead isotope abundances of environmental samples collected from Helsinki area were determined. The separation of lead from samples were carried out using wet ashing and anion exchange. For the determination of the lead isotope ratios a thermal ionization mass spectrometer type MI-1309 was used. The average ratio of Pb-206/Pb-204 in air filter, lichen and incinerator ash samples were 17.5+−0,3, 17.7+−0.3 and 18.4+−0.4, respectively. The mean value of the ratio Pb-206/Pb-204 in gasoline was 16.42+−0.24. This value being significantly lower than in other samples analyzed gives an opportunity to evaluate the contribution of motor traffic to lead content of environmental samples.

Rapid determination of lead for industrial hygiene surveys

Emphasis on the continued reduction of personnel exposure to airborne lead has led to the development and evaluation of portable instrumentation for the rapid determination of microgram quantities of lead collected on air filter samples. The instrumentation is based on radioisotope-induced X-ray fluorescence; a cadmium-109 radioisotope source is used for sample excitation, and the characteristic lead X-rays emitted are measured by a proportional detector. The effects of excitation source geometry, particle size, and interferences from other elements were investigated. This type of portable instrumentation appears ideally suited for in-plant measurements intended to monitor lead and evaluate new control measures.

Identification of atmospheric particulate sources in Washington, D.C. using chemical element balances

During the summer of 1976, 130 air-filter samples were collected at 10 sites in the Washington, D.C., area and analyzed for 39 elements, with 37 samples also being analyzed for SO/sub 4//sup 2 -/, NO/sub 3//sup -/, and NH/sub 4//sup +/. Concentration patterns were interpreted by using chemical element balances for seven sources: coal, oil and refuse combustion, soil dust, motor-vehicle emissions, limestone, and marine aerosols. For 35 nonvolatile elements, predicted concentrations were, on the average, within a factor of 1.93 of observed values. Predicted concentrations of primary particulate matter plus SO/sub 4//sup 2 -/, NO/sub 3//sup -/, and NH/sub 4//sup +/ account for 65% of measured total suspended particulate (TSP) matter, the remainder presumably being condensed water, organic material, and sources not included. The largest fraction of primary TSP matter is soil, dust, much of which is entrained by urban activities. The limestone component may originate from agricultural liming, construction projects, or abrasion of concrete. Most elements are reasonably well fitted, major exceptions being Cr, Cu, Ni, and a small-particle component of Mn.

Characteristics of water adsorption on air sampling filters

The objective of this work was to determine the error induced in air sampling filter weights by water adsorption. The weight gains caused by water adsorption at various temperatures and relative humidities were measured. The relationship between the concentration of water in the air and filter weight gain was determined. The relationship was determined for various filter materials and filters of the same material from different manufacturers. The weight gain was found to be a potentially significant source of error for filters of all types. The use of desiccation prior to weighing under ambient conditions in order to reduce this error was found to be ineffective.

214Bi/214Pb activity ratios in the atmosphere

The ratios of 214Bi to 214Pb in the surface atmosphere at Bombay on the west coast of India have been measured. In all, about 500 measurements were carried out at the ground surface and on top of a building 20 m high. The analysis techniques consisted in the least squares resolution of the alpha decay curves of high volume air filter samples counted by using large ZnS scintillation detectors. The collection and counting periods were optimized for minimizing the errors. The sample collection procedure consisted in taking a morning and an afternoon sample everyday. The measured ratios varied from 0.3 to 1.0, the average values being in the range 0.6–0.9. The afternoon ratios were generally higher than were the morning values. The data also showed that during late winter and spring the ratios reached the minimum values observed during the year. The possible reasons for the variations in the measured ratios are discussed.

Airborne plume study of emissions from the processing of copper ores in southeastern Arizona

The elemental composition of particulate materials in the plumes of five copper smelters in southeastern Arizona was determined. Air-filter samples were collected with a light, twin-engine aircraft. Arsenic, lead, cadmium, zinc, selenium, tungsten, indium, and other volatile and chalcophilic elements are highly enriched in the plume materials relative to the background aerosol. Marked differences in the element composition of plumes from the various smelters could be used as ''''fingerprints'' to determine contributions of material from various plants at a specific impact point. (5 graphs, 27 references, 1 table)

A Radiochemical Microtechnique for the Determination of Traces of Ammonia And Ammonium Salts

Abstract A radiochemical procedure for the determination of traces of ammonia and ammonium ions in aqueous solutions is presented. In a buffered medium ammonia is precipita- 203 203 ted by Hg(II) as Hg2NCl. If the same amount of the radioreagent is always employed, a negative linear correlation is obtained between the amount of ammonia to be determined and the activity of the supernatant liquid. Combining a microdiffusion preconcentration step with the radiochemical procedure the working range of the new method can be extended to amonia concentrations as low as 0.04μN/ml. The method is applied to the analysis of rain water and air filter samples and compared with the indophenol blue technique.

A case of transport and deposition of Saharan dust over the Italian Peninsula and southern Europe

A severe case of Saharan dust transport and deposition with rain over Italy and southern Europe has been investigated by combining all available data including meteorological information, analyses of air sampling filters and sampled dust with rain, and satellite information on cloud cover. This typical straight transport case is characterized by a trough oriented south‐north, a cold front on the mobilization area, and a warm advection from the south. Meteorological analysis included relative topography, maps of pseudo‐potential temperatures, and barotopographies of ϑp = 45°C. The conditions of dust mobilization have been investigated and strong updrafts and thermals, with and without concomitant convective clouds, proved to be responsible for it. The size distribution of particles in rainfall residue has shown two modes, with diameters around 0.2 and 1 μm. X ray diffractometric analysis and SEM pictures have shown that the two modes are also different in composition, the smaller particles being composed of clay platelets and the larger of quartz grains. The mass concentration of the dust layer has been evaluated in 154 μg/m3. Wet removal through in‐cloud scavenging processes was the effective mechanism of deposition of the dust, as muddy rain has been observed at the ground long before the dust was observed in air sampling filters at mountain stations.

Recent IAEA intercomparison on the determination of trace elements in simulated air filters

Results of a recent intercomparison on the determination of trace elements in simulated air filter samples are reported. A large scatter of results is obtained for some elements and systematic differences between laboratories are observed. The performance of different methods, in particular neutron activation analysis and atomic absorption spectrophotometry, used by the various laboratories is discussed (air filter analysis; intercomparison; trace elements; control charts).