AIRBORNE PARTICLES AND HEALTH

This chapter discusses the effects of airborne particles on health. Nuisance problems of dusts and other small particles arise mainly when the particles become airborne and escape into the general environment. Dust control is thus usually concerned with airborne particles, preventing their formation, controlling their movement, or affecting their separation. Sometimes the purpose is economic—to prevent the loss of a product or process material. More commonly, dust control is undertaken to avoid the harmful effects—hygienic or otherwise—of dust in the environment. Apart from general considerations of cleanliness and good housekeeping, dust may contaminate products, abrade machinery, create an explosion hazard, or above all, be dangerous to health. Dry dust particles are weakly coherent due to molecular forces that are not well understood. The presence of small quantities of condensed water greatly increases particle adhesion. The dispersion of dust as an aerosol requires the application of a disruptive force to achieve an initial separation of the particles, after which further dilution will take place by turbulent mixing with the surrounding air. The disruptive force may be produced mechanically or by aerodynamic drag.