A cleanroom is a controlled environment with stringent requirement where provisions are made to minimize particulate contamination and regulate other environmental parameters such as temperature, humidity and pressure. Cleanrooms are classified according to the number and size of particles permitted per volume of air. For cleanroom class 1000 (refer to FED_STD_209E), it maintains less than one thousand particles larger than 0.5 microns in each cubic foot of air space. It is equivalent to ISO class 6 cleanroom (refer to ISO 14644-1).

Particulate contamination controls are highly depending on its filter system, known as High Efficiency Particulate Air (HEPA) filter where it is used to trap different particle sizes, typically 0.3 micron and above in size. Particles are trapped in the filter when air delivered to cleanroom passes it. Other control measurements include only allow cleanroom compactible material used in cleanroom and personnel training on contamination control in all cleanroom activities, especially on cleanroom garment.