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The collection efficiency of Whatman 41 filter paper has been determined using submicron test aerosols of monodispersed polystyrene latex. Measurements were made over a velocity range of 12 to 195 fpm, using aerosols with diameters of 0.088, 0.188, 0.264, 0.365, and 0.557 mu . For sizes less than 0.557 mu , well-developed efficiency minima occur in the velocity range of 20 to 30 fpm. In no case was the efficiency found to be below 70%. At 195 fpm, the efficiency was essentially size-independent. (auth)

The penetration of particles through IPC 1478, Whatman 41, and Type 5G filter papers has been measured by using monodispersed polystyrene latex aerosols at ambient temperature and pressure. The aerosols were 0.264, 0.365, 0.557, 0.796, and 1.099 microns in diameter and consisted of more than 85% single particles. Initial electronic charge on the test aerosols was reduced with a radiation source to an average elemental electronic charge per particle of 0 to 3. Penetration was measured through filters at air velocities from 0.1 to 100 cm/sec. Well-defined velocities for maximum penetration for each particle size were found for the three filter papers. Particle sizes for maximum penetration were also found for IPC 1478 and Type 5G papers as a function of air velocity.

IPC-1478 filter paper efficiency was evaluated using polystyrene latex and dioctyl phthalate (DOP aerosols). Efficiency was measured as a function of particle size, filtration velocity, and filter mass loading. Experimental results of 0.557-µm and larger particle sizes indicate that this medium has limited effectiveness under high-velocity and high-loading conditions. Differences in efficiency were observed when this medium was tested with solid and liquid aerosols.

This article reviews the information on the climatic effect of carbon dioxide and aerosols and outlines man's part in contributing to their occurence. Recent downward trends in the average surface temperature of the biosphere has lead some scientists to conclude that albedo increases due to the effect of aerosol backscatter is the causative mechanism. While there is evidence for and against this hypothesis, this paper emphasizes that albedo changes due to aerosol modification of cloud cover may be a more significant mechanism for explaining temperature trends.

A study of the forward collection efficiencies of paper-coated glass and copper cylinders (diameters of 7.5 and 4.0 cm) was conducted in a wind tunnel in which the flow was turbulent. Dibutyl phthalate droplets of MMD 1.3 microns were collected in air-flow velocities of 16.8, 12, and 8.3 mph. Deposition by inertial impaction was precluded by selection of these particle sizes, wind velocity, and cylinder size. The forward collection efficiencies were less than 1% in all cases (greater for the paper-coated glass cylinders than for the paper-coated copper). In general, the forward collection efficiency increased with the reciprocal of the cylinder diameter and was greater at 16.8 mph than at 12.0 and 8.3 mph. At the turbulence intensities used in this work (0.5%, 1.8%, and 4.7%), intensity of turbulence had no effect on forward collection efficiency.

Oil mist can be efficiently collected on filter paper or by an electrostatic precipitator. Samples containing 0.05 mg of oil can be accurately determined by ultraviolet spectrophotometry. Gross amounts of sample contaminants, such as soil, water, and pipe scale, can be tolerated without appreciable loss in accuracy. Petroleum distillate vapor is efficiently collected on silica gel or in a midget bubbler containing chloroform. Maximum collection efficiency is achieved at sampling rates not exceeding 100 cc/min. Samples containing as little as 0.5 mg in 10 ml of chloroform or ethanol may be determined by spectrophotometry. With both oil and petroleum distillate determinations, it is necessary to obtain a sample of the particular product in question in order to construct a standard spectrophotometric curve.

Several filter media were evaluated by using liquid (0.3 µm DOP) and solid (approximately 0.3 µm polystyrene latex) test aerosols. Data were obtained for each medium at velocities ranging from 4 to 190 fpm. Below 100 fpm, Whatman 41 filter paper has a significantly higher efficiency when tested with solid aerosols. Below 40 fpm, IPC 1478 also has a significantly higher efficiency when tested with solid aerosols. Instrumentation limitations prevented measuring any significant differences for the high-efficiency media tested. Aerosol agglomeration and charge effects were eliminated by using an impactor and by establishing charge equilibrium for the solid aerosols. Average electron charge on latex particles was reduced to 0.7, and the test aerosol consisted of 86 to 97% single particles. The effects of filter loading on efficiency and pressure drop was also measured. Whatman 41 efficiency was significantly increased owing to loading with polystyrene latex aerosols. This did not occur with DOP.

Bronchilator is a triple-drug aerosol containing isoetharine, phenylephrine (a vasoconstrictor and mild bronchodilator), and thenyldiamine (an antihistamine). American workers (Spiel man, 1961 ; Siegel, 1962 ; Goldfarb and Romanoff, 1962) have reported the value of the triple aerosol in bronchial asthma, and its freedom from side-effects even in hypertensive patients. The aim of this work is to compare objectively the degree and duration of effect of Bronchilator1 with that of isoprenaline2 and a placebo aerosol3 in a double-blind controlled study.

A procedure was developed for evaluating high-efficiency filters mounted in exhaust ducts at the National Animal Disease Laboratory. An aerosol of the test organism, Escherichia coli B T 3 bacteriophage, was generated in a chamber attached to a ceiling exhaust register in concentrations of at least 1000 viable organisms per ft 3 of air. Samples were collected from both the pre- and postfilter areas, and the number of organisms per ft 3 of air was determined. The efficiency of the filter was calculated from these figures. A total of 269 high-efficiency filters were tested. Of these, 249 had efficiencies of 98% or greater. The remaining 20, with efficiencies of less than 98%, were repaired and retested. No filter was accepted with an efficiency of less than 98%.

Infectious diseases, such as infectious hepatitis, may be transmitted from patients to staff in clinical laboratories and dialysis units during the performance of necessary procedures. This prompted us to examine the propensity of several items of commonly used apparatus to produce aerosols of infected blood. These were a microhaematocrit centrifuge, an AutoAnalyzer stirrer, and a microtonometer. We also compared some blood sample tubes with two types of lid. The results showed that all of these are potential sources of infection for laboratory staff.

Andersen air samplers were used to determine the particle size distribution of Serratia marcescens aerosols created during several common laboratory procedures and simulated laboratory accidents. Over 1,600 viable particles per cubic foot of air sampled were aerosolized during blending operations. More than 98% of these particles were less than 5 μ in size. In contrast, 80% of the viable particles aerosolized by handling lyophilized cultures were larger than 5 μ. Harvesting infected eggs, sonic treatment, centrifugation, mixing cultures, and dropping infectious material produced aerosols composed primarily of particles in the 1.0- to 7.5-μ size range.

A new large-volume air sampler called the “simple liquid scrubber” is described. It can recover a high percentage of microorganisms from large volumes of air, up to 950 liters/min, and concentrate them into a small volume of liquid at a ratio of about 400,000 to 1. The principle of operation of the scrubber is based on the production of a fine mist in a rapidly moving airstream with ultimate collection of the airborne particles by impingement into the film of liquid formed upon impaction of the mist droplets on the scrubber walls. The scrubber compared favorably with the all-glass impinger (AGI-30) and the slit sampler in tests with the normal flora and with experimental aerosols of Bacillus subtilis var. niger spores.

The influence on airway conductance of inhaled aerosols of prostaglandin F(2)alpha (PGF(2)alpha), histamine, and prostaglandin E(2) (PGE(2)) was studied in 10 patients with spirometrically reversible bronchial asthma and in 10 healthy subjects with no history of lung disorder. Both groups responded with bronchoconstriction after inhalation of PGF(2)alpha but the asthmatic patients were about 8,000 times more sensitive to the compound than were the healthy controls. In the patients, but not in the controls, PGF(2)alpha often caused a long-standing decrease in airway conductance with symptoms resembling allergen-provoked asthmatic attacks. On the other hand, the patients showed less than a 10-fold increase in sensitivity to histamine, and the ratio of histamine: PGF(2)alpha doses causing a 50% decrease of airway conductance was 2.6:1 and 2,400:1 in controls and patients respectively. Inhalation of PGE(2) while moderately but consistently increasing airway conductance in controls, had a variable-occasionally slight bronchoconstrictive-effect in patients. The decrease in airway conductance by a given dose of PGF(2)alpha was little modified by the simultaneous inhalation of a 100-times higher PGE(2) dose. It is suggested that endogenous, locally formed PGF(2)alpha may play an important part in the pathogenesis of bronchial asthma.

1. After inhalation of doses of 3H-albuterol (84 and 220 μg) by humans, plasma radioactivity reached a max. after 2 and 4 h, respectively.2. About 72% of the inhaled dose was excreted within 24 h i...

The bronchodilator and cardiac effects produced by aerosols of 0·5% isoprenaline and of 0·25, 0·5, and 1% salbutamol administered in 40% oxygen by intermittent positive-pressure ventilation were compared in 24 asthmatic patients. Isoprenaline and salbutamol in concentrations of 0·5% were equipotent in peak bronchodilator effect; salbutamol was superior in total bronchodilator effect and duration of average effect, but the peak bronchodilator effect occurred earlier after isoprenaline. Significantly greater tachycardia was produced by 0·5% isoprenaline than by the same concentration of salbutamol. The 0·25, 0·5, and 1% concentrations of salbutamol had about the same peak bronchodilator effect, but there was a stepwise increase in total effect and duration of average effect in relation to the concentration used. A similar stepwise increase in heart rate was also noted, but with all concentrations this was significantly less than with 0·5% isoprenaline. It was concluded that a 0·5% solution of salbutamol, which provided maximal bronchodilatation without important tachycardia, was therapeutically superior to the other three treatments.