Micron

A micron is one thousandth of a millimetre or a millionth of a metre, so 1 micron can be written as 10-6 m. The SI symbol for micron is µm. Considered particle sizes for cleanroom classification according to ISO 14644-1:2015 are between 0.1µm and 5µm dependent on the class of cleanroom. Considered particle sizes in GMP cleanrooms are usually 0.5µm and 5µm, however additional or alternative particle sizes can be measured if requested by a client.