The rules and special procedures needed to clean a cleanroom, and how they differ from ordinary cleaning.

A CLEANROOM CAN BE DEFINED as a high-tech, controlled environment where the concentration of airborne particles, humidity, and temperature are all controlled to parameters specified by the ISO 14644.

As science progresses, the demand for cleanrooms in bio-tech, pharmaceutical, medical device, semiconductor, and nanotechnology continue to grow. As the demand for these controlled environments increases, it becomes more and more critical to develop and implement effective contamination control programs. The purpose of these programs is to ensure that any material, substance, or energy that adversely affects the product or process is eliminated, or at least, minimize to safe levels.

What is Contamination?
There are two broad categories of contamination; particulate and microbial. Non-viable particulate contamination is defined as a solid or liquid generally between .001 and 1000 microns in size. Examples of particulates are dust,fumes, smoke, fogs, and mists.

Viable particulate contamination can be defined as a particle that consists of, or supports one or more live microorganisms. Bacteria, viruses, and spores are all examples of viable particulate contamination.

Sources of Contamination
By far, the human factor is the largest contributing factor to the amount of contamination inside a cleanroom. Skin cells are constantly shed from people. The entire epidermis or outer layer of skin is replaced approximately every four days. Oils from the skin are shed; hair is shed. And whatever is ona person’s skin or hair is ultimately deposited into the cleanroom.

In addition to human beings, equipment transfer into the cleanroom can contribute greatly to the amount of particulate contamination inside the cleanroom, as can the tools, fluids, and the products that are manufactured.

With all of these external factors allowing damaging particulate contamination to enter the controlled environment, it is crucial to develop a contamination control program to combat such a barrage of potential contamination.

Contamination Control Methods
Since the human factor is the biggest contributor to the contamination problem, the first level of defense should be a comprehensive training program for all personnel who enter the cleanroom. The training should begin with the concept of a cleanroom and which elements from the outside world need to stay in the outside world. A well-designed training program examines all elements of contamination and how to best prevent particulates from entering the environment in the first place. A Standard Operating Procedure (SOP) should be prepared and reviewed by all cleanroom staff. The SOP is a written document with specific action steps to be taken in the contamination controlprocess.

Proper gowning or garment selection should be made in accordance with the class of cleanroom and product requirements. This may include hairnets, shoe covers, face covers, gloves, frocks, or full coveralls. The SOP will define the gowning procedures for entrance, work, and exit from the cleanroom. It is also a good idea to implement a gowning certification program. This program will periodically assess the ability of each person entering the cleanroom to don gowning apparel without contaminating it, judged by a microbiological assessment of the gown itself at various points.

Figure 1: Lint free polyester or PVA mops attached to stainless steel handlesare required for mopping.

Shouldn’t Training and Gowning Solve Everything?
The personnel understand how a cleanroom works. Everybody knows that there are things from the outside environment that need to stay outside of the cleanroom. The staff is qualified and capable of donning gowning apparel. This should take care of all of the contamination, right? Wrong. No matter how well people are trained, and how well they follow gowning procedures,external contamination will always enter the cleanroom.