What do cleanroom personnel and doctors have in common? Hold that question for a moment while we examine some truisms.

It’s been more than forty years since cleanrooms were developed for the aerospace industry. Since then, the physics and chemistry associated with achieving clean surfaces has matured and is now believed to be well understood. Given that many companies need pristine surfaces for the manufacture of defect-free products, one might well ask why, forty years later, we should still be facing contamination issues and related product failures due to lack of proper wiping and surface cleaning? Certainly the high-quality wiping and cleaning products, the training aids, and the auditing programs are all available. Perhaps there’s another factor at play.

One problem with keeping cleanrooms clean is that we were given the ability to visually resolve objects only down to 50 micrometers (µm) — about 2/1,000thof an inch. If we were able to see contaminants such as particles and bacteria smaller than 50 µm, the reaction would likely be “Oh, gross!,” and we would not hesitate to wipe away the offending contaminants. So, the difficulty is that we assume that surfaces are clean, because to our limited visual capability they look clean.

But our eyes deceive us, or rather, what we can’t see deceives us. Literally, we just can’t see the problem.

In the pharmaceutical and medical device fields, the FDA requires a reasonable measure of surface cleanliness through existing regulations and the threat of plant closures. The health dangers of a bacterial-contaminated injectable drug solution or an endotoxin-laden catheter support the need for such regulations. These contaminants are too small to be seen, so manufacturers put in place stringent cleaning/sanitizing/disinfecting processes to ensure pristine surfaces. The operative principle is “Assume the surface is contaminated and proceed accordingly.” There are no corresponding regulations in the semiconductor, flat panel, and data storage areas (should there be?) where yields rather than health threats tend to drive contamination control (i.e., wipedowns).

Now consider the parallel situation in the health-care arena, say a doctor on rounds in a hospital. If his/her hands were visibly grimy there would be no hesitation about washing up before examining a patient. But, because the hands look clean, the washing step is often skipped, even though there is an awareness that clean-looking hands can still harbor harmful bacteria (up to 5 million colony forming units per cm2!). It is estimated that hospital personnel wash or disinfect their hands about half as often as they should. So, the doctor on rounds has the same problem as cleanroom personnel — the contaminants are too small to be seen to prompt corrective action. But diligence has its rewards.

Atul Gawande’s book “Better” and Kevin Sack’s recent article “Swabs in Hand, Hospitals Cut Deadly Infections” both describe dramatic reductions of methi-cillin-resistant Staphylococcus aureus (MRSA) infections (from 60 annually to 17 last year) at a VA hospital in Pittsburgh. Part of the improvement was attributed to improvements in hand cleanliness.

The newest group to encounter more stringent requirements for contamination control are the compounding pharmacists who must conform to the recent USP <797> protocols. They are encouraged not to be misled by “apparent” cleanliness but rather, to “Assume the surface is contaminated and proceed accordingly.” That way, they will not allow their eyes deceive them.

Howard Siegerman, Ph.D., is a consultant with Siegerman and Associates. He can be reached at hsiegerman@verizon.net.