by Ken Goldstein, Ph.D.
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When cleanroom and contamination control people sit around the campfire and tell stories, all kinds of really interesting and old stuff tends to come out. The point of this exercise of course is to impress others with just how long we've been involved in this type of work. A few examples: “I remember when… people ate lunch at their cleanroom workstations” or “no one wore cleanroom bunny suits” or “Federal Standard 209B was new,” or even ” 'cleanroom' was two words.” Some of you are nodding at this point.
Another of these defining tales relates to being able to remember when cosmetics were still commonly worn in cleanrooms. The difference here is that this one seems to come back every few years to bite us. Indeed, this subject seems to have raised its head again recently. For complicated reasons, this topic seems to have more lives than the legendary Count Dracula. Somehow, we need to drive a stake into this thing and kill it once and for all. There is really no good reason for us to keep visiting this topic except around the campfire.
The rule
The general rule is that cosmetics should not be worn in cleanrooms. Period.
The only exception to this is the possible use of moisturizing lotions or creams (with very little in the way of coloring agents) that may be worn by those few individuals with extremely dry, flaking skin. Beyond this one possibility, it is difficult to think of any other exceptions to the rule.
Because normal cosmetics are potential contaminants, they should not be brought into the cleanroom. Their very presence inside contamination-sensitive areas violates the first rule of contamination control: “Never bring anything into the cleanroom unless it absolutely has to be there.” And of course this necessity is dictated by product and process requirements, not the desires of the human operators.
Please note that this “rule” does not say you should not bring contaminants into the cleanroom. That is understood and implied and follows from commonly accepted definitions of the terms “cleanroom” and “contaminant.”
Recall that a cleanroom is a room in which the airborne particle concentration is controlled to some predetermined level. And a contaminant is anything that can have a harmful effect on the process or product with respect to either quality or reliability.
This last definition seems to be rather open-ended while leaving a lot of room for future expansion. And indeed, that is exactly the case.
Over time, contamination-sensitive products have become faster, smaller, smarter and more reliable while simultaneously becoming more sensitive to contamination. In other words, contamination levels that were once acceptable may become intolerable. This helps to explain why our first rule of contamination control talks about “things” instead of “contaminants.”
Substances that may be relatively harmless at one point in time can evolve into serious contaminants. And control should be exerted over all things entering the cleanroom, not just currently known contaminants.
Of course, all of this only applies to cleanrooms with fairly stringent requirements. You could reasonably argue that the use of cosmetics would have relatively little impact in an ISO Class 8 (Class 100,000) cleanroom. But the rule of “no cosmetics” should probably be enforced in all facilities that are ISO Class 7 (Class 10,000) or cleaner.
And to be consistent, the rule should probably be enforced in all cleanrooms on sites where there is at least one cleanroom in the ISO Class 6 (Class 1,000) or cleaner category, even those less clean than this arbitrary cut-off. The point to this is to create a single unified code of behavior for operators, maintenance people, managers and whoever else is required to enter the contamination-sensitive areas. Gowning requirements may differ but the cosmetics rule should not.
Thirty years ago, we used to give cosmetics little thought in terms of product and process contamination. About twenty years ago, we learned that cosmetics contain a wide range of possible contaminants.
Looking at them qualitatively, we find significant quantities of iron (Fe), aluminum (Al), titanium (Ti), magnesium (Mg), potassium (K), sulfur (S) and carbon (C). In the microelectronics world (semiconductors, integrated circuits, storage media and devices, flat panel displays, etc.) these are all capable of significantly impacting both quality and reliability levels. Ditto for aerospace devices. In the area of pharmaceutical products, these contaminants are forbidden because they commonly slough off people with the potential for carrying bacteria and other bio-burden with them.
In an upcoming issue, we will look at some of the studies that first led to the adoption of the no cosmetics rule.
Dr. Ken Goldstein is a principal with Cleanroom Consultants Inc. (Scottsdale, AZ) and is a recognized expert in planning and designing of cleanrooms and ultrahigh purity systems. He has been associated with the cleanrooms industry for 20 years, and is a senior member of the IEST. He is active in WG-012 (Cleanroom Design) and WG-028 (Minienvironments).
Don't miss Ken's conference presentation at CleanRooms East 2001 in Boston, March 12 at 9:00 am. To register for this or any other CleanRooms East '01 conference session, please call (603) 891-9267. Early bird registration deadline is 2/5/01.