Friday, July 10, 2009

Controlling Human-Caused Contamination

The greatest source of contamination in a cleanroom is people. By simply walking around, the human body can generate five to ten million skin, hair, dirt, and clothing particles every minute. This is why cleanroom garments have been developed. Cleanroom garments are generally white suits composed of a hood, coveralls, and booties. The suits are specially cleaned and packaged garments made of very tightly woven fabrics that are designed to filter human particles in the cleanroom - reducing them by a factor of ten in most cases.

Cleanroom Garments
Only approved cleanroom garments should be worn in the cleanroom. Always use the proper dressing procedure: the hood is tucked into the coveralls, which are tucked into the booties. Gloves are worn over the coverall arm. Keep hair tucked under the hood at all times. Never unzip or open the garment in the clean-room. Hang the garments in a vertical laminar flow bench or on separate racks when not in use. Put garments in clean-room-dedicated garment hampers after use.

Personal Clothing
Avoid wearing clothing made with natural fibers as they shed particles that can migrate outside cleanroom garments. Clothing made from synthetic materials are generally more practical for working in a cleanroom.

Jewelry and watches should not be worn in the cleanroom, as they retain many dead skin flakes that can shed into the cleanroom if they puncture a glove.

Mascara, fingernail polish, hair spray, face powders, colognes, perfumes, and other cosmetics are a source of particles and should not be used.

Gloves are worn to protect hands from corrosive and hazardous solvents and to protect products from skin and dirt particles. Check to see the gloves specification and process requirements are compatible. Gloves should generally be disposed of each time after exiting the cleanroom.

Wipe glasses and goggles clean of any visible contamination before entering the cleanroom.

Food, drink, and chewing gum should not be allowed to be brought into the cleanroom.

Smoking should not be allowed in or near the cleanroom. When a person smokes, smoke particles are still breathed out over half an hour later. If a person does smoke on breaks, drinking a glass of water before re-entering the cleanroom has been shown to greatly reduce residual smoke particles

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