Protective cleanroom clothing essentials
Everything that enters a cleanroom must also be highly regulated to prevent the inadvertent introduction of pollutants, which includes protective cleanroom clothing.
Cleanrooms are environments where levels of dust, aerosol particles, microbes and other contaminants are controlled. They’re essential for research and manufacturing in a variety of industries, from aerospace to pharmaceuticals. In order to maintain cleanliness levels, everything that enters a cleanroom must also be highly regulated to prevent the inadvertent introduction of pollutants. For the people who work in these environments, protective cleanroom clothing is designed to do that.
Yet cleanroom clothing is not only important in protecting against contamination in controlled environments, as it also serves to protect those working in cleanrooms from hazardous liquids or particles. US Occupational Safety and Health Administration (OSHA) 29 CFR 1910 mandates that employers must provide suitable personal protective equipment (PPE) such as goggles and respirators in cleanrooms when necessary. Choosing the right items to protect both workers and sensitive operations is no simple task, but here are basics everyone should consider when setting up a cleanroom.
Different classes of protective cleanrooms
A cleanroom is defined by its level of contamination, which is determined by the number of airborne particles per cubic meter that are acceptable for an environment to be considered clean. These particles can be anything from dust to dead skin cells, dandruff, and even mold or yeast.
The US General Service Administration’s FS209E standard was previously used to classify clean rooms, but in 2001 the ISO 14644-1 system was adopted worldwide. This system contains nine classes ranging from ISO 1-9, which provide for two additional “cleaner” classes and one “dirtier” class than the former FS209E standard.
ISO 7, which was considered Class 10,000 under the former standard, is a common type of cleanroom used in electronic or medical device manufacturing where 352,000 particles of less than 0.5 microns in size is allowed per cubic meter. An ISO 1 cleanroom, on the other hand, is of a level of cleanliness not measurable by the FS209E standard and that allows only 10 particles of less than 0.1 microns per cubic meter. This kind of cleanroom is rare and used, for example, by the European Space Agency.
Types of protective cleanroom clothing
Along with air filtration, special protective clothing is used to prevent cleanroom contamination. Various types of cleanroom clothing offer different levels of protection on all parts of the body. These can include bouffant caps, hair nets and hoods for the head, frocks or lab coats, aprons, sleeves and coveralls for the body, and shoe covers or boots for the feet. Goggles, gloves and face masks are also particularly important, not only for maintaining clean environments, but as PPE for workers as well. In some cleanrooms, respirators may also be necessary to ensure workers are not exposed to hazardous substances.
Cleanroom clothing is often available as disposable or reusable garments. Disposable garments are convenient and effectively prevent contamination, while reusable garments are better for the environment and can also reduce costs in the long run. Reusable garments are more durable can be cleaned and sterilized in-house or with a cleaning service, but repeated washing does eventually cause them to break down over time and release particles that compromise cleanliness.
Choosing the right protective cleanroom clothing
There are various factors to consider when choosing the right protective cleanroom clothing. Of primary concern is of course ISO class. Each class has a recommended list of clothing and frequency at which it should be changed. For example, the recommendation for ISO 8 is a bouffant cap, face mask, frock, gloves and shoe covers that are changed at least twice per week. Yet in ISO 3, the entire body should be protected with coveralls, with some parts requiring multiple layers, such as a bouffant cap, face mask and goggles together with a hood.
There are other factors to keep in mind that may depend on the industry or type of cleanroom. For example, clothing that has lower potential to generate static electricity is important in cleanrooms producing semiconductors. There is also the question of how often clothing must be changed, and if reusable or disposable garments are more suitable from both a cost and cleanliness perspective.
Material weight, thickness, durability, barrier properties, and even comfort should also be considered. There is a variety of materials that are typically used to create most cleanroom clothing, each with its own pros and cons. Common materials include:
- Single-layer polypropylene PP—A thermoplastic polymer that is used in combination with other materials in most disposable garments, including bouffant caps and beard covers. It is low cost and can be made in a variety of weights and thicknesses.
- SMS: With three layers of PP—two layers of lightweight and breathable spun-bonded PP and a layer of melt-blown PP in the middle—this material is durable, breathable and splash resistant.
- Microporous—Made with PP thermally laminated to a layer of polyethylene, which provides a good barrier yet has poor breathability. This material is extremely durable and clean and is often also used in surgical environments.
Beyond material, the fit of garments on workers and between different items is also important. Clothing should not be so tight as to restrict movement, but items that are too large or fit together poorly can create gaps where skin or hair particles can come through.
As you can see, there’s much to consider in selecting protective cleanroom clothing, and equipment needs to be tailored to each individual circumstance. Yet all these different factors also underline the importance of getting it right, ensuring that the many different routes of potential contamination don’t get in the way of running a successful and safe operation.
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