Of the many potential sources of contamination in cleanrooms and other clean production areas, none is greater than the people working in them.
There are many possible sources of contamination of the cleanroom environment. Materials, structures, equipment and surfaces can generate particles through friction and degassing. Incoming production equipment can introduce contaminants. However, it is the people working in cleanroom that generate the most particles.
- On one cm2 of hand surface area, there is an average of 1,500 microorganisms.
- One cm2 of skin surface on the human body contains an average of 5 million bacteria.
- Every minute of the day, people lose about 30,000 to 40,000 dead skin cells from the surface of their skin.
- Even when stationary, humans produce about 100,000 particles of 0.3µm or larger. In motion, this increases to about 5 million.
- The clothing procedure for sterile cleanroom clothing takes an operator between 5 and 10 minutes on average.
Cleanroom management
The fundamental aspect of cleanroom management is an efficient cleanroom management programme that keeps the air free of suspended particles. Apart from the fact that particles themselves can cause contamination of products, particles are also a microbiological problem. Since a particle can be a carrier of microorganisms, particles are the main spreaders of microbiological contaminations.
Operators working in the clean room produce millions of particles with every movement. Schlieren's thermal images can show particles emitted from the human body. The particles migrate up through the cleanroom clothing to the head or fall down from the legs during cleanroom activities.
Microorganisms
Bacteria, fungi and yeast are organisms that are chemically active. The by-products of their growth and multiplication can cause a variety of contaminants in the cleanroom. Most feared are the endotoxins that can cause poisoning symptoms. Humans also release elemental chemicals that can cause contamination:
- Saliva: potassium, chloride, phosphorus, magnesium, and sodium
- Head dandruff: calcium, chloride, carbon, and nitrogen
- Sweat: sodium, potassium, chloride, sulphur, aluminium, carbon, and nitrogen
- Fingerprints: sodium, potassium, chloride, and phosphorus
But most particles released by humans consist of skin cells, including the microorganisms that live on our skin.
Follow the hygiene protocol
Therefore, a critical component of cleanroom management is strict compliance with hygiene rules. ’Since people are the biggest potential contamination risk, they are also the biggest focus of contamination control’.A thorough, comprehensive training programme discussing all aspects of cleanroom management will enable cleanroom operators to reduce the degree of contamination during the production process. When operators are aware of the polluting consequences of their behaviour, they can take their own measures to adapt their behaviour to the particular circumstances.
Conduct requirements include, but are not limited to, the following:
- Cosmetics are banned because in addition to their particle generation, cosmetics release iron, aluminium, silicone, carbon, titanium, magnesium, potassium, sulphur, and calcium.
- Smoking is not allowed inside the production facility including all clean room areas. Smokers emit tar particles for at least half an hour after smoking one cigarette. Recall that if you smell that a smoker has just had a smoke break, you smell contamination. Smokers produce 150 times more particles when coughing than non-smokers.
- Nothing is allowed inside the cleanroom that is not used in the production process. This includes personal items such as jewellery, mobile phones, keys, food or drinks.
- Hair cannot be combed in clean room, including changing room.
- Only compatible ballpoints and logbooks are allowed within cleanroom for data capture.
- Cleanroom clothing is worn as prescribed. The method of changing clothes is also critical. Clothes should be changed regularly and disposables (hairnets, mouth and beard caps, overshoes) should be thrown in the appropriate waste bins.
- Speaking is restricted. Speaking over products and work surfaces is prohibited. This is because talking spreads particles over a distance of up to 1 metre. These particles naturally also contain the natural oral flora.
- Movements and walking should be performed calmly. The more intense the movement the more particles are produced.
- Before and after work, cleaning and decontamination of the workplace and production tools should be carried out according to cleaning instructions and line clearance protocols.
- Hand washing is mandatory when entering the cleanroom, after touching the face or dirty surfaces, after eating, after smoking, after visiting the toilet and before and after wearing gloves. Here, the hand washing protocol should be followed.
The degree of regulation depends on the air quality required. Rules and management means used for producing medical devices, which are sterilised after manufacture, are insufficient for the aseptic preparation of medicines.
The effectiveness of the measures is continuously monitored by measuring the biological contamination of products, surfaces and air, and measuring airborne particles. Cleanroom management is determined by the choices made by the operator, guided by the monitoring results.