Principle of microbial air sampler by impact method on agar plate

Air containing microbe-carrying particles is aspirated and accelerate through a hole and direct towards a nutrient agar surface of a plate. As the air turns away from the agar surface, the microbe-carrying particles that cannot follow the flow are impacted. The plate containing nutrient agar is then incubate at a suitable time and temperature, and the resulting Colony Forming Units (CFU) are counted to evaluate the number of microbe-containing particles collected from a specific volume of air.