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Typical Pollutant Sizes That Cause Down Time
Bacteria
.01 to 1.0 Microns
Dust
1.0 to 10 Microns
Mold
1.0 to 10 Microns
Hair
10 to 100 Microns
Pollen
10 to 100 Microns

 

Following are some common sources of contamination.
Hair
Skin Flakes
Saliva
Make-Up
Chemicals
Caulks and Paints
Lotions
Perfumes
Coughing / Sneezing
Excessive Movement
Aerosols
Ions (Rust)
Perspiration
Wood
Paper
Cardboard
Permanent Markers
Non-Cleanroom pens
Gum, Cough Drops
Packing Materials
Duct Tape
Dirty Clothing
Smoke
Thinners /Solvents

 

To combat the tremendous amount of particulate released by the human body, cleanroom personnel are asked to wear special garments that are restrictive and may be uncomfortable if the working conditions (temperature, humidity) are not carefully controlled.

People are dressed in booties, gloves, helmets, hoods and special facemasks that are not part of a normal experience. You are also asked to move slowly, to clean up dirt you cannot see, and to follow practices and procedures that may not immediately make sense.

The approach to cleanrooms is designed in steps so as to ensure that every effort has been made not to introduce contaminants into the cleanroom.

 

The Human Factor

“Humans are walking, breathing, waste pits from a microbiological perspective and there is no indication we are going to evolve into anything cleaner.” Human dust combined with sebum will tenaciously adhere to and contaminate surfaces, creating contamination problems that are simultaneously bacterial, chemical and particulate. There is an additional complicating factor – normal human activity. Humans breathe, sneeze, cough, talk and move around. Body and breath temperatures cause heat turbulence in addition to air turbulence. People slough off huge numbers of particles a half micron and larger and these are propelled around by air and body movement. Some examples of how many 0.5 micron and larger particles can be released by simple movement are shown below. Vast amounts of contamination need to be controlled in a cleanroom environment.

Activity
Particles Release
Seated
100,000 particles per minute
Moving 2 miles per hour
5 million particles per minute
Moving 3.5 miles per hour
7.5 million particles per minute
Moving 5 miles per hour
10 million particles per minute

 

Contaminants, Sources and Potential Damage
Type
Source
Damage Potential
Metallics
Vacuum cleaner motor brushes, wear of A/C units, printer wear, raised floor and grid
Electrically conductive, magnetically attracted to micro-circuits
Carbonaceous
Automobile exhaust, tobacco smoke, printer toner, oxidized organic material, paper dust
Moisture absorbent, electrically conductive, combustible.
Synthetic Fibrous Particulate
Operator clothing, carpeted floor tiles
Low melting point, moisture absorbent, some type combustible , electrically conductive.
Cement Dust/Crystalline
Improper sealing or erosion of subfloor, ionization and crystallization of cleaning fluids, nicron wire heating elements, ion air purifiers.
May be propelled at high velocity into floor cooled components, clogged filters lead to overheating of disk media