William C. Hinds

Size characteristics of cigarette smoke

The aerodynamic size distribution of cigarette smoke was measured using an aerosol centrifuge and a cascade impactor. The observed size distribution was log normal with an initial mass median aerodynamic diameter which decreased from 0.52 to 0.38 mu m as the dilution was increased from 10:1 to 700:1. The average geometric standard deviation was 1.38. The differences between these results and those reported by other investigators are attributed to differences in measurement methods.

A Method for Measuring Respiratory Deposition of Cigarette Smoke During Smoking

An understanding of the factors influencing respiratory deposition of cigarette smoke in smokers is needed to accurately control this important source of respiratory exposure in epidemiological studies of workers. Only a few studies have characterized the deposition of cigarette smoke in smokers and these involve methods that interfere with normal smoking. A technique for measuring puff volume, inhaled amount, and respiratory deposition of cigarette smoke particulate phase has been developed. It provides satisfactory accuracy (+/- 10%) and causes minimal disruption of normal smoking pattern. The technique captures exhaled smoke with an exhaust hood and establishes the amount of inhaled smoke by monitoring puff volume, puff duration, and puff timing and replaying the exact smoking sequence with matched cigarettes. Mass of captured cigarette smoke is evaluated by fluorophotometry. Preliminary trials with 11 paid volunteers gave an average puff volume of 53 mL and smoke deposition ranged from 22% to 75% with an average of 47%. Measured depositions are lower than previously published values and higher than would be predicted for submicrometer sized particles during normal breathing.

Concentrations of Nicotine and Tobacco Smoke in Public Places

PUBLIC interest has focused on health effects to the large numbers of nonsmokers exposed to tobacco smoke in public places. Recent regulations in a few cities have banned smoking in public places, ...

An iron oxide aerosol suitable for animal exposures

Abstract An aerosol generator has been constructed which produces submicronic iron oxide particles from the combustion of iron pentacarbonyl, Fe(CO)5. If operating conditions are chosen with care, CO levels will be below 5 ppm when mass concentrations are as high as 340 mg/m3. The aerosol is suitable for animal exposures since it is relatively nontoxic and is easily quantitated by techniques of chemical analysis. The particles reach the pulmonary alveolar surface where they are readily recognized by light and electron microscopy. These aerosols are ideal for use in morphological studies on the pathways of particle clearance in the lungs.

Size Distribution of Aerosols Produced by the Laskin Aerosol Generator Using Substitute Materials for DOP

Test aerosols of di(2-ethylhexyl)phthalate (DOP) produced by the Laskin nozzle aerosol generator are widely used for in-place filter testing and respirator fit testing. Concern about health effects of DOP has led to a search for substitute materials for use as a test aerosol. Aerosols were generated with a Laskin generator and diluted 4800-fold with clean air. Size distributions were measured for DOP, di(2-ethylhexyl)sebecate, polyethylene glycol, mineral oil, and corn oil aerosols with a PMS ASAS-X optical particle counter. Distributions gave count median diameters from 0.22 to 0.30 µm. Size distributions varied little with aerosol material, operating pressure, or liquid level. Mineral oil and corn oil gave the closest agreement to the DOP size distribution.

Control of Indoor Radon Decay Products by Air Treatment Devices

An evaluation of the efficacy of household air cleaning devices as a means to control radon decay products in existing buildings is presented. Previous research on air cleaning methods for airborne radon decay products has been directed primarily to the control of radon decay products in mines and has only limited application to control in residences where dust concentration, air change rate, and humidity are lower than in mines. Results show that room size air cleaners can achieve substantial reductions in working levels in residences. Reductions observed at air infiltration rates of 0.52 air changes per hour ranged from 58 to 89%. Although the two air cleaners tested produced the greatest reductions, the low cost, simplicity, and other benefits of air circulating fans, particularly the ceiling fan, appear to make them most suitable for residences. (JMT)

An experimental animal model for quantifying the biologic effects of marijuana on the defense system of the lung.

An animal model was developed as an inhalation bioassay for acute and chronic delivery of tobacco and marijuana smoke in physiologic doses to the lungs of experimental animals. Although generating identical aerosols, the pyrolyzation characteristics of marijuana and tobacco differed considerably. Both products impaired host intrapulmonary antibacterial defenses, with marijuana appearing in comparable dosages to be significantly more toxic to the alveolar bactericidal activity of the lung than tobacco smoke. The effect of both smoking products on mucociliary clearance by the airways, in this model system, appeared to be negligible. Direct biologic comparisons between the effects of the two smoking products must be guarded, however, as dosimetry cannot be precisely equated because of their opposing physiologic effects on the lung.

Emergency Respiratory Protection with Common Materials

The efficacy of readily available materials, such as cotton fabric, toweling, and a single-use respirator, for providing emergency respiratory protection was evaluated by determining the filtration efficiency as a function of particle size over the range of 0.4 to 5 µm diameter and performance against a reactive water soluble (I2) and unreactive vapor (CH3I). At a reasonable design face velocity (1.5 cm/s), the respirator mask used at double thickness could reduce particle concentrations a factor of 30 or more throughout the particle range tested, and a wetted towel four layers thick could provide a factor of five. Dry fabrics were ineffective in removing iodine vapor, but wetted sheeting or toweling reduced concentration by a factor often or more under design conditions, 1.5 cm/s face velocity and 50 Pa pressure drop (0.2 inches of water). The fabrics provided a statistically insignificant reduction in methyl iodide. In practice, any leaks around the seal to the face would lessen the protection offered b...

High Velocity Filtration of Submicron Aerosols

Filtration efficiency tests were conducted on fiberglass mat filter media with (a) DOP aerosol having a count median diameter of 0.8 µm and a geometric standard deviation of 1.65, and (b) uniform polystyrene latex spheres of 0.36, 0.66, 0.80, and 1.1 µm diameter over a face velocity range of 500 to 3000 fpm. Filtration of submicron aerosol particles by a fibrous filter is characterized by a face velocity that yields a minimum collection efficiency. Removal efficiency increased with increasing velocity for liquid DOP aerosol particles, but the solid polystyrene latex aerosols showed a significantly different penetration vs. velocity relationship in the high velocity filtration region. These differences are partially explained by assuming that only a fraction of the polystyrene latex particles adhere on contact and the remainder rebound back into the air stream. When compared to a high energy scrubber, the advantages of high velocity filtration for submicron industrial effluents are (a) compactness of equip...