Introduction to Cleanrooms

Cleanroom at NASA.
Cleanroom at NASA.

Think your employees have a hard time leaving their smart phones, ear buds, campaign buttons, pizza slices and whiskey bottles in the locker room before entering a FOD-sensitive area? In some industries, you can’t even smear a little chapstick on your lips. Welcome to the cleanroom.

Originally developed in 1961 by Sandia Laboratories and based upon innovations in World War Two-era factory designs, the modern cleanroom (also spelled “clean room”) is a sealed indoor environment where the level of airborne, surface and other tiny pollutants is so strictly controlled that even your own skin can create FOD.

Semiconductor and other microelectronics manufacturers can build ever-smaller and more efficient devices. Pharmaceutical companies and biomedical device builders can manufacture super-sanitary medicines and hospital machines. Researchers can study nanotechnology and develop microscopic designs.

Many of these pollutants are too small for the human eye to see, especially in small quantities. Examples include dust, microbes, skin flakes, droplets, vapors, and aerosol particles. Even the thin film of detritus that contaminates visually-clean surfaces, such as tables and machine housings, can destroy a production line.

Small contaminants originate from many sources. Humans shed all manner of particles, such as hair, skin flakes and debris from cosmetics. Small chips and dust break off of parts and tools, plus their coatings emit vapors. Cleaning solvents emit vapors, and water can grow bacteria. A room itself produces paint flakes, air conditioning debris, and even its own air pollution.

Furniture and Filters

Cleanrooms, such as this one at Valcor Engineering, are carefully designed. Tables and other furniture should be constructed from (or covered with) stainless steel, Formica or other sterile materials. Sometimes a table will be perforated with holes to help the room’s air to recirculate more efficiently. Tools are likewise vetted for suitability. Pencils can leave graphite residue, so only pens are allowed, which must be one-piece with no removable buttons.

Cleanroom at Valcor Engineering.
Cleanroom at Valcor Engineering.

HEPA (High Efficiency Particulate Air) and ULPA (Ultra-Low Penetration Air) filters remove air particles smaller than one micron in diameter. Additional filters remove particles from liquids and gasses, plus temperature and humidity are also kept under tight control. The circulation and replacement of air flowing through room is regulated not only via fans and other devices, but also the architectural design of the room itself.

Air locks, filters, and sometimes air showers are employed to strip contaminants from individuals and objects before entering the room. Personnel wear special clothing, hair nets, gloves, and goggles or face shields. Much like a FOD-critical area, they may bring only limited personal items with them. Makeup and perfume may be forbidden, due to the potential for detritus and out-gassing.

Just as with FOD parts- and tool-control procedures, personnel must label and track all beakers, notebooks and other working items brought into the cleanroom. To prevent unwanted air turbulence, they are discouraged from making abrupt body movements. Engaging in “horseplay” is specifically forbidden.


In order to be credible, a cleanroom needs to meet certain industry standards. In the USA and much of the world, the original document was FED-STD-209E. In 2001, 209E was canceled in favor of the more comprehensive ISO 14644-1, although 209E remains popular with many organizations. In Europe, GMP Annex 1 is the governing document.

But all of this works only if management commits to keeping the cleanroom clean. In 2012, severe negligence at the New England Compounding Center, a wholesale pharmacy in Massachusetts, led to the deaths of at least 48 people. They were among the 14,000 patients nationwide who had been injected with medicines contaminated with meningitis.

Government investigators visiting the cleanroom discovered mold growing inside of vials, and also learned that personnel had shut off the air conditioning every night. The company ended up declaring bankruptcy and federal agents arrested one of its pharmacists as he tried to flee the country.

So, the next time you find yourself worrying about your company’s FOD control requirements, think about all of the little whatchamacallits that you just breathed in, but don’t have to worry about.

In the United States, you can also acquire the ISO-14644 series at IEST (Institute of Environmental Sciences and Technology).

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