Airborne particle deposition in cleanrooms: Relationship between deposition rate and airborne concentration

This article is the second of a series that discusses the deposition of airborne particles onto cleanroom surfaces. It investigates the relationship between the airborne concentration of a range of cumulative sizes of particles and the particle deposition rate (PDR) onto cleanroom surfaces, through knowledge of the deposition velocity of particles in air. The deposition velocity of a range of cumulative particle sizes was obtained by means of experiments, theoretical calculations, and literature search and the influence of a number of variables found in cleanrooms on the deposition velocity was investigated. The use of the deposition velocity to calculate the amount of deposition on cleanroom surfaces, such as manufactured products, is discussed, along with its use in deciding the required ISO 14644-1 class of cleanroom; these subjects will be discussed in more depth in the final article of this series.