History of Impactors - The first 110 years

This history of impactors detailed in this article covers the time span from 1860 to 1970. The origin of the inertial impactor was in the time period from 1860 to 1870, and the very first impactors were essentially the same as they are today-a jet of particle-laden air impinging on a plate. Impactors have a history of going through spurts of development. In the 1800s, impactors allowed researchers for the very first time to quickly collect particles and inspect them under a microscope to study the relationship between dust and disease. This was an exciting time for researchers, and these early impactors were used extensively. The next spurt of development was about 1920, when impactors were rediscovered in the form of konimeters, dust counters, and impingers, which were considerably more advanced than the impactors of the 1800s and were used extensively for determining the dust concentrations to which industrial workers were exposed. These instruments were used in different forms until the mid 1940s when the cascade impactor was developed. The discovery of the cascade impactor, along with extensive theoretical analysis of jet impaction in the early 1950s, led to much activity in cascade impactor development. In 1970, with the help of finite difference techniques and high-speed computers, a parametric study of impactors was made which unlocked nearly all of the secrets of how to design an impactor. From 1970 forward, the design of impactors became rather routine, and numerous impactors of all shapes and sizes for all manner of purposes were designed and built.