What’s in a number?


ISO cleanroom standards continue to give solid foundation to contamination-control community

by Richard A. Matthews, Filtration Technology, Inc.

Numbers have meaning, and described below are a few numbers that have particularly significant meaning to the contamination-control community. The most important of these is 209-or more precisely ISO/TC209. Another is 1993-the year the ISO/TC209 technical committee on “Cleanrooms and Associated Controlled Environments” was formed. The results of this 12-year effort are the ten international cleanroom standards you see listed in chronological order in Table 1 together with their current status. These numbers, and the standards they represent, clearly have very detailed and important meaning for anyone concerned about contamination control. And, as the years pass, they will continue to have meaning to an ever-growing number of people.

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The committee and the process

The ISO/TC209 technical committee was the result of a 1992 petition by the Institute of Environmental Sciences and Technology (IEST) to the American National Standards Institute (ANSI) requesting that the International Organization for Standardization (ISO) create a new technical committee on international cleanroom standards. This IEST request was precipitated by the knowledge that, in Europe, the E.U. nations were seeking to create European cleanroom standards via the CEN (Committee for European Normalization) standards body.

The U.S. recognized that its Federal Standard 209E, last revised in 1992, could easily be rendered obsolete by this European activity. More importantly, the U.S. Federal Standard was widely accepted internationally and the U.S. wanted to maintain a position of influence in the writing of international cleanroom standards.

The first meeting of ISO/TC209 was held in Chicago in November 1993. Five working groups were created to tackle the task of creating international cleanroom standards from the multitude of national standards and regulations, along with the various cleanroom criteria, established by specific trade associations and professional societies. Four additional working groups were established later as the subject matter expanded. There are currently nine working groups (see Table 2).

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Over the past twelve years, ISO/TC209 has met seventeen times. Well over 1000 people from 39 nations have been involved at various levels, from the ISO Technical Committee to national mirror standards bodies, to in-country expert councils, to ad hoc groups, to presentations at technical meetings soliciting current technical input, to lots of correspondence-initially with letters and telephone calls, then faxes, and now e-mail. We have witnessed and effectively utilized the changing technology of communications.

The activity of ISO/TC209 has been based upon risk assessment, quality goals, yield, and the process idiosyncrasies that provide consistent quality output in a clean, controlled environment.

The personnel involved in this standards-writing activity came from a wide variety of contamination-control backgrounds and experiences-design engineers, microbiologists, scientists, contractors, equipment manufacturers, educators, regulators, standards writers, process engineers, research and development personnel, validators-all with the purpose of providing a solid, global baseline for the cleanroom community.

In the various working group and technical committee meetings there certainly was controversy. In the end, however, consensus overrode contentiousness. There was a general spirit of cooperation and harmonious effort for the common good of the contamination-control community.

The standards

ISO 14644-1 is the keystone document in this series of cleanroom standards. It establishes the classes of air cleanliness and how to measure for a particular class. There are 9 major classes and an additional 72 subclasses for fine-tuning clean space. These 81 classes are a significant expansion of what was in U.S. Federal Standard 209E.

ISO 14644-2 was the second standard created and it is a companion document to ISO 14644-1, for it specifies how often clean areas need to be tested to prove compliance with the classes of air cleanliness in ISO 14644-1.

ISO 14644-3 outlines the 14 different test methods that can be used to test the value of clean space. Three of these tests are mandatory per ISO 14644-2 and 11 others are optional (i.e., selected per agreement between buyer and seller).

ISO 14644-4 outlines the criteria to be considered when designing and building clean space. It is a broad-spectrum document written to provide an overview of what parameters need to be considered. Annex H of this document is an excellent checklist for anyone involved with designing, building and operating cleanroom environments.

ISO 14644-5 covers the major aspects of manufacturing and living in a cleanroom environment. It requires an end user to carefully assess the criteria to be considered for effective and efficient cleanroom operations. It is a “must” document for anyone operating a cleanroom.

ISO 14644-6 will be the last of the original 10 ISO cleanroom standards to be published. It is the compendium of terms and definitions used in the other 9 documents.

ISO 14644-7 is the most original of these 10 ISO cleanroom standards. It basically covers self-contained clean space in which personnel are not present. It covers clean benches, isolators, minienvironments, and glove boxes-all devices that personnel access from outside the clean, controlled environment of the individual units. It describes in detail the design, construction and operational necessities of independent, peopleless clean space.

ISO 14644-8 covers the issue of molecular contamination. This standard currently covers airborne molecular contamination (AMC) and establishes methods for measurement and analysis. It offers an airborne molecular classification rating system that allows end users to define the amount and type of molecular contamination as well as the collection and analysis methods used for establishing its rating.

ISO 14698-1 deals with the general principles and methods of biocontamination control in a cleanroom environment where a formal system of control is required. It establishes criteria for corrective action.

ISO 14698-2 is a companion document to ISO 14698-1, as it deals more specifically with the evaluation and interpretation of bio­contamination data in risk zones as appropriate.

Unfortunately, this article cannot cover all aspects of these cleanroom documents. However, copies of these standards are available from the IEST Web site at All contamination-control specialists should become familiar with these documents.

The creation of these first ten international cleanroom standards effectively completes phase one of the work of ISO/TC209. The technical committee set out to produce baseline documents for the control of particulate contamination, biocontamination, and molecular contamination in cleanrooms and associated controlled environments. This work is essentially complete, awaiting only final formal votes from the ISO member bodies on two documents.

Phase two

The next phase of ISO/TC209 entails the required five-year review of ISO published standards. ISO 14644-1 and 14644-2 have already passed the five-year mark and comments have been solicited from the cleanroom community. Working Group #1 has been reconstituted and met twice in 2005. It expects to have suggested revisions and/or modifications to ISO 14644-1 and 14644-2 for review and vote in 2006. By this five-year review process, the ISO cleanroom standards are living documents that will remain current with the cleanroom community’s needs and changing technology.

In addition, other phase two activities include new work on cleanroom standards for particulate and molecular contamination on surfaces. Other future cleanroom standards will be developed as new contamination- control technology challenges arise to meet market demands.

For example, ISO/TC209 has already begun interfacing with the newly formed ISO Technical Committee on Nanotechnology (ISO/TC229). It is obvious that the ISO cleanroom standards are active, living documents subject to change and have a controlling influence in the cleanroom community.

Passing the baton

During the past twelve years, I personally have found the work of ISO/TC209 very rewarding. The opportunity to interface with different people from diverse disciplines and cultures is a broadening experience. It has also given me the opportunity to visit various parts of the world. In retrospect, the over 1000 people who have contributed to the work of ISO/TC209 shared a common goal of success. Expanding on this success now becomes the responsibility of David E. Brande, who assumes a six-year term as the new chairman of ISO/TC209. Brande is the founder and president of Contamination Control Technologies, Inc., a certifier of cleanrooms and biological safety cabinets and a consultant to pharmaceutical, medical device and biomedical industries. He has a broad background and extensive international experience in contamination control. He is past president of CETA and an active member of IEST, NEBB and ISPE.

Richard A. Matthews is founder of Filtration Technology Inc. (Greensboro, NC) and president of Micron Video International, Inc. He was chairman of the International Organization for Standardization Technical Committee ISO/TC209 “Cleanrooms and Associated Controlled Environments” from 1993 to 2005 and past president of the IEST. He is also a member of the CleanRooms Editorial Advisory Board.

ISO facts and fiction

It is purely coincidental that the ISO Technical Committee on “Cleanrooms and Associated Controlled Environments” was given number 209. When this new technical committee was approved by ISO, the next sequential number in its committee system was 209. It could just as easily have been 208 or 210. This coincidence did rattle some European members who believed that the U.S. was using undue influence to push its Federal Standard 209E criteria on the ISO activity. This is totally inaccurate: The use of the number 209 might have been serendipity but it was not subterfuge.

One of the major modifications in the work of ISO/TC209 was the nomenclature system for defining classes of air cleanliness. The Federal Standard 209E classifications were intuitive: When someone referred to “Class 100” or “Class 10,000” it was easy to get a sense of the relative cleanliness of one area versus another. There was strength of meaning in these old numbers. Unfortunately, ISO required the use of a sequential numbering system, which resulted in ISO/TC209 using the numbers one through nine (one being the cleanest) to designate classes of air cleanliness. Thus, “Class 100” became ISO Class 5 and “Class 10,000” became ISO Class 7, making it much more difficult to create a mental picture. Since two or three generations of contamination-control professionals are ingrained with the Federal Standard 209E classifications, and since that standard was canceled in 2001, it may take some time to become accustomed to the new ISO system of air cleanliness classes.

Richard A. Matthews is founder of Filtration Technology Inc. (Greensboro, NC) and president of Micron Video International, Inc. He was chairman of the International Organization for Standardization Technical Committee ISO/TC209 "Cleanrooms and Associated Controlled Environments" from 1993 to 2005 and past president of the IEST. He is also a member of the CleanRooms Editorial Advisory Board.