Disk motor heads deformed, unusal sounds from harddisk which lead to the unreadable of the data, salvaging data in clean room is necessary to avoid further damage.
If hard disk is physically damaged, recovered in a clean room is a must.

Class 100 clean room, which maintains less than 100 particles larger than 0.5 microns in each cublic foot of air. Which ensure the data recovery under the general clean room regulations.

In the confined space, control of humidity, temperature, number of particles and contamination are strictly enforced. This area may be over ten million times purer than a hospital operating room.

Dust free corridor

The level of clean room is classified according to how much particulate of specific sizes existed in certain volume. Class 100, Class 1000 known as FED-STD-209E standard, which is smaller than 100 and 1000 particles (0.5 microns or larger) per cubic foot of air respectively.
According to ISO 14644-1, 0.1µm was the standard diameter to measure the number of particles per cubic meter. For example, an ISO 5 clean room allows 100,000 or below particles per cubic meter only.
The assumption of FS 209E and ISO 1466-1 determined by the particles size and their amounts. Assumed that the number of particles as zero based, and 1 Cubic Meter = 35 Cubic Feet. Baed on it, and typical particles size set as 0.5 μm, althought there are two different standards, but ordinary room air is approximately class 1,000,000 or ISO 9.

On November  29, 2001,  the U.S. General Services Administration (GSA) issued a notice ofcancellation for the Federal Standard 209E (FED-STD-209E), however, it is still widely used.

BS 5295-1 Part1: Specifications for Clean Rooms and Clean Air Devices, all samplings must be smaller than 0.5 μm.

If the engineerers opened the harddisk cover in the spotless environment, the data will be perfectly safe.

Engineerers wore anti-static PU palm coated copper glove suck out the discs with cautions.