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Air pollution
2021-07-07
External source of pollution
The concentration of atmospheric dust
Atmospheric dust is the object to be directly dealt with in the clean room. In the clean technology, the most commonly used concentration is the number of particles ≥0.5μm. In the cleanest stratosphere (10km from the surface), there are about 20 particles /L of such particles, and about 2600 particles /L over the very clean sea. The count concentration in the air of China can be roughly divided into "industrial city", "suburban city", "non-industrial or rural area". The particle concentration of ≥0.5μm is 1×106 particles /L, 2×105 particles /L and 3×105 particles /L, respectively.
Concentration of atmospheric bacteria
The pollution of atmospheric dust belongs to the pollution of inanimate particles, while the pollution of atmospheric bacteria belongs to the pollution of living particles. Microorganisms include: viruses, rickettsiae, bacteria, fungi, protozoa. But it's mostly bacteria and fungi that are associated with clean rooms. However, bacteria can not live alone and are generally attached to dust particles, so the significant size is its equivalent diameter. When a group of bacteria-carrying particles pass through the filter, the filtration efficiency of bacteria is the same as that of particles of a certain particle size, so this particle size is the equivalent diameter of this group of bacteria-carrying particles.
Internal contamination
Send dust
The amount of dust in the clean room, from the equipment can be considered through local exhaust to eliminate, not into the clean room; Products, materials and other dust in the process of handling compared with the amount of human dust, generally small, can be ignored. Due to the use of good metal wall decoration in clean room, the amount of dust from the surface of the building is also very small, generally accounting for less than 10%, and the dust mainly comes from people, accounting for about 90%.
Microbial hair
(1) When the staff in the clean room wear sterile clothing:
The number of bacteria at rest is generally 10 ~ 300 /min. people
In general activities, the amount of bacteria is generally 150-1000 /min. people
When walking at a brisk pace, the number of bacteria is generally 900 ~ 2500 /min. people
(2) A cough is usually 70 ~ 700 times /min. people
A sneeze is generally 4000 ~ 60000 /min. people
(3) Bacteria quantity when wearing ordinary clothes: 3300 ~ 62000 /min. people
(4) Fungus amount without mask: Fungus amount with mask is 1:7 ~ 1:14
(5) Fungus quantity: dust quantity is 1:500 ~ 1:1000
(6) The number of bacteria in the operation: 878 /min. people
Therefore, it can be known that the static bacteria quantity of people wearing aseptic clothes in clean rooms is generally more than 300 /min. In human, the number of dynamic bacteria is generally less than 1000 /min. people
The concentration of atmospheric dust
Atmospheric dust is the object to be directly dealt with in the clean room. In the clean technology, the most commonly used concentration is the number of particles ≥0.5μm. In the cleanest stratosphere (10km from the surface), there are about 20 particles /L of such particles, and about 2600 particles /L over the very clean sea. The count concentration in the air of China can be roughly divided into "industrial city", "suburban city", "non-industrial or rural area". The particle concentration of ≥0.5μm is 1×106 particles /L, 2×105 particles /L and 3×105 particles /L, respectively.
Concentration of atmospheric bacteria
The pollution of atmospheric dust belongs to the pollution of inanimate particles, while the pollution of atmospheric bacteria belongs to the pollution of living particles. Microorganisms include: viruses, rickettsiae, bacteria, fungi, protozoa. But it's mostly bacteria and fungi that are associated with clean rooms. However, bacteria can not live alone and are generally attached to dust particles, so the significant size is its equivalent diameter. When a group of bacteria-carrying particles pass through the filter, the filtration efficiency of bacteria is the same as that of particles of a certain particle size, so this particle size is the equivalent diameter of this group of bacteria-carrying particles.
Internal contamination
Send dust
The amount of dust in the clean room, from the equipment can be considered through local exhaust to eliminate, not into the clean room; Products, materials and other dust in the process of handling compared with the amount of human dust, generally small, can be ignored. Due to the use of good metal wall decoration in clean room, the amount of dust from the surface of the building is also very small, generally accounting for less than 10%, and the dust mainly comes from people, accounting for about 90%.
Microbial hair
(1) When the staff in the clean room wear sterile clothing:
The number of bacteria at rest is generally 10 ~ 300 /min. people
In general activities, the amount of bacteria is generally 150-1000 /min. people
When walking at a brisk pace, the number of bacteria is generally 900 ~ 2500 /min. people
(2) A cough is usually 70 ~ 700 times /min. people
A sneeze is generally 4000 ~ 60000 /min. people
(3) Bacteria quantity when wearing ordinary clothes: 3300 ~ 62000 /min. people
(4) Fungus amount without mask: Fungus amount with mask is 1:7 ~ 1:14
(5) Fungus quantity: dust quantity is 1:500 ~ 1:1000
(6) The number of bacteria in the operation: 878 /min. people
Therefore, it can be known that the static bacteria quantity of people wearing aseptic clothes in clean rooms is generally more than 300 /min. In human, the number of dynamic bacteria is generally less than 1000 /min. people
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