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Small enough to penetrate to deep lung areas chemically quite reactive. Less than 1 um up to 1 mm regular in shape some crystalline materials length to width ratio less than 3:1 with some notable exceptions.8 FUMES Fine solid aerosol particles produced from the re-condensation of vaporized material that is normally solid at standard conditions is melted and vaporized condensation (0.01 um) occurs during cooling of vapor – nucleation coagulation – agglomerates at 1 um in diameter are nearly spherical. Chemically unchanged smaller size and higher specific surface area may enhance ability to be airborne, inhaled, penetration, toxicity, solubility or explosion. Examples: mining material handing dry material prep and packaging. Incidentally addresses bioaerosols or aerosols of biological origin.6 DEFINITIONS Forms of Aerosols: Dust (also crystalline materials) FumesMists Fogs Smokes Fibers (length exceeds diameter)7 DUSTS Particulate aerosols produced by mechanical processes such as breaking, grinding, and pulverizing. Evolving ultrafine and nano-sized aerosols. A single technique is not appropriate IH must be familiar with properties and assessment techniques. Incidentally addresses bioaerosols or aerosols of biological origin.5 ASSESSMENT TECHNIQUESTechniques for sampling and analysis continue to evolve for characterization of aerosols. Asbestosis, Silicosis, Coal (black lung), dust. Assumes dust is insoluble/solid when deposited in alveoli of lung. Recent universally accepted definition of “the accumulation of dust in the lungs and the tissue reaction to its presence”. Occupational aerosol hazards recognized by: - Pliny -Ěgricola - Ramazzini - Sir Percival Pott Least toxic as “nuisance dusts” ACGIH – PNOC or OSHA with parallel term – PNOR.4 PNEUMOCONIOSIS Derived from Greek means “dust in the lungs”. Range of > 50 um to microscopic particles invisible to naked eye. so, - health effects – irritation, illness, disease.3 AEROSOLS Aerosol – described as solid and/or liquid particles dispersed in a gaseous medium. Variables include: - size, shape, and density - chemical properties - airborne concentration and time of exposure, and other factors, etc. Inhaled particles may react with or be absorbed through tissues to cause adverse health effects. 1 INDUSTRIAL HYGIENE - AIRBORNE PARTICULATESUNIVERSITY OF HOUSTON – DOWNTOWN2 INTRODUCTION Introduce the techniques available for Industrial Hygienists to recognize, evaluate exposures to particulates, and control in occupational settings.