Ten Commandments of a Cleanroom: Do’s and Don’ts when entering a cleanroom
A cleanroom is an enclosed space where the presence of airborne particles are controlled and classified. Each cleanroom is classified depending on the sub-micron particles that it contains. The air inside a cleanroom is strictly regulated to ensure that the right quantity and size of particles per volume of air is maintained.
There are 9 ISO classifications, ISO 1, ISO 2, ISO 3, ISO 4, ISO 5, ISO 6, ISO 7, ISO 8, and ISO 9. ISO 1 is considered the cleanest while ISO 9 is considered the dirtiest. The basis of cleanroom standards is the micrometer or micron. Each ISO classification uses the same formula: particles/m3 of air.
This table from part 1 of the ISO 14644 series best illustrates the maximum concentration limit per cleanroom.
Maintaining a cleanroom’s integrity requires a detailed risk analysis and the resulting recommendations in limiting these risks form the basis of the Standard Operating Procedures (SOP) for the cleanroom. Users need to be thoroughly trained on these SOPs regularly in order to maintain the high levels of cleanliness required.
Different processes will identify different risk factors but there are a few basic procedures that we would simply define as best practice. Here are the ten commandments of a cleanroom.
- Thou shall leave personal items outside of the cleanroom
All of the items you bring into a cleanroom carry with them a risk of contaminating the cleanroom. This is why all staff must carry only essential items inside the room. Provide your employees with lockers so they can store their personal belongings before they enter your cleanroom.
- Thou shall not eat, smoke, or drink inside the cleanroom
This is pretty self-explanatory. Eating, smoking and drinking (even water) should be strictly prohibited inside the cleanroom. The main complaint we hear and experience ourselves as cleanroom users is dehydration. Cleanrooms rely on a high air change rate and this dehydrates you. Scheduling regular breaks for cleanroom workers and installing a water fountain outside the cleanroom help to elevate this problem.
- Thou shall not enter the cleanroom wearing makeup or perfume
These days we must add to this no false eye lashes, hair or nails. Humans shed approximately 106 particles (>0.5 µm diameter) per hour (You et al., 2013; Bhangar et al., 2015) and adding additional particulate and uncontrolled substances (such as those found in these cosmetics; polymers, oil, wax, iron oxides, titanium dioxide the list goes on) into the cleanroom is to be avoided.
- Thou shall not make unnecessary movements inside the cleanroom
Quick and rapid motions will increase the amount of particulates shed as well as agitating particulate (i.e. dust) present in your cleanroom. Movement in a cleanroom should be kept to a minimum and when it is necessary the movement should be slow and controlled.
- Thou shall not enter the cleanroom sick
Entering a controlled environment when you’re unwell can compromise the entire space around you.
- Thou shall wear proper cleanroom gowning materials
Your risk assessment will have identified the size and concentration of particles that will compromise your procedure. It should also identify the most likely source of these particles and how it is best to protect against this. Each cleanroom will therefore have a different gowning procedure and this should be taken into account when entering a new cleanroom. The purpose of the garments are to capture the skin cells, hair, sweat, and other bodily particles which would otherwise compromise your cleanroom process.
- Thou shall cover all exposed hair, including facial hair
It is normal to shed between 50 and 100 hairs a day. Protecting your process against such obvious contamination is vital.
- Thou shall observe good personal hygiene
Before touching any gowning garments all cleanroom staff should observe good personal hygiene including hand washing to avoid contaminating the cleanroom robes.
- Thou shall not sit or lean on surfaces
In order to keep contamination of the surfaces and equipment within the cleanroom to a minimum contact with such surfaces and equipment should be restricted as mush as possible. Be mindful of your contact and movement within the cleanroom.
- Thou shall not touch your face or hair
Feeling itchy? Did a stray hair strand get out of your bouffant? Avoid the reflex to scratch that itch. Practice extreme self control when you’re inside the cleanroom. If these circumstances happen, you need to exit the room as soon as possible.
Maintaining a cleanroom’s integrity requires vigilance from all users. In order to maintain the high standards required we would recommend regular training of all users, even the management and carefully positioned posters reminding users of the SOPs can also prove very useful.
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