C. Roth

Generation and properties of a condensation aerosol of di-2-ethylhexyl sebacate (DES)—I: Description of the generator

Abstract In an improved generator of the Sinclair-La Mer type monodisperse droplets of di-2-ethylhexyl sebacate (DEHS) in the 0·08–4 ,μm dia. range were produced by condensation of DEHS-vapour on sodium chloride nuclei in a stream of pure nitrogen. The nuclei were produced by electrical heating of a NaCl-coated platinum wire. Their size and concentration depend on the nitrogen flow rate and the heating current as proved by electron microscopy and monitoring of the nuclei concentration. The final size distributions of the DEHS aerosols were evaluated by optical spectrometry. The geometric standard deviation of the size distributions varied between 1·035 and 1·06.

A laser spectrometer for size analysis of small airborne particles

Abstract The particle size distribution in an aerosol is measured by analysing the light scattered by each particle in a nearly forward direction. The particles are illuminated with a laser beam, the light scattered is collected by a microscope objective and passed to a red sensitive photomultiplier, the amplified output pulses of which are stored in a multichannel pulse height analyser. The signal-to-noise ratio of the spectrometer makes it possible to measure particles down to 0–1 μm in diameter. This sensitivity was obtained by focusing both the laser beam and the aerosol stream.

Generation and properties of a condensation aerosol of di-2-ethylhexylsebacate (DES—III: Experimental investigations into the process of aerosol formation

Abstract The process of aerosol formation by controlled condensation of di-2-ethylhexylsebacate (DES) vapour upon NaCl-nuclei is investigated experimentally. The mean droplet size of the condensed aerosol is measured as a function of the nuclei concentration and the saturation vapour pressure in the boiler. If the nuclei concentration is reduced from 10 6 to 10 5 cm −3 homogeneous condensation is no longer suppressed and a coexistence of two kinds of aerosol droplets of different size can be observed. Experiments are performed showing the influence of the nuclei size and the flow conditions in the chimney upon the departure from monodispersity.

Uptake of electrical charges in the human respiratory tract during exposure to air loaded with negative ions

Abstract The uptake of negative charges in the human respiratory tract has been determined experimentally by breathing free ions and particles carrying negative charges. Free ions are deposited very effectively in the upper airways whereas charged particles penetrate to the deeper lungs.