The history of cleanroom clothing has seen many technological changes over the decades. Early cleanroom concepts of controlling contamination of an environment can be seen hatching as far back as the American Civil War when front-line surgeons noted the environmental risks of surgery in the field. During the 19th century, hospital operating rooms were about the only places that used rudimentary cleanroom principles to stave off infection. Early in the 20th century as World War I’s invention of the gas mask created high-efficiency particle air (HEPA) filters, the cleanroom as we know it today began to take shape.
Hospitals have led the way for many technologies used in cleanrooms today including the disposable glove. This invention had nothing to do with cleanliness as the world had not yet fully accepted Louis Pasteur’s germ theory proposed in 1881. But Joseph Lister had Lister had developed a machine that broadcast a fine mist of carbolic acid around the surgical site. Combining use of this machine with washing surgical instruments in the same solution reduced the death rate of Lister’s surgical patients from close to 50% to 15% in 1870. So, medical facilities rapidly adopted these practices.
It was this very invention of using sterilizing mist that would set the stage for the invention of disposable gloves. The skin-irritating carbolic acid and mercuric chloride used as disinfectants during surgeries led to a nurse complaining about skin rashes caused by the soap and caustic disinfectants that had been adopted for surgery to prevent infection.
In May of 1889, in response to her complaints, Dr. William Stewart Halstead, chief of surgery at Johns Hopkins Hospital in Baltimore, Maryland, contacted Goodyear Rubber Company to design the world’s first pair of disposable rubber gloves. Click the link to read the story of how the disposable gloves were invented as it is interesting: the complaining nurse was a rebellious lady from a prominent southern US family who became a nurse despite her family’s protests (she was the niece of a famous Confederate general) and she later became Dr. Halstead’s wife.
Note that these were disposable rubber gloves. The modern disposable latex gloves more akin to what we think of in cleanrooms today was first manufactured by Ansell in 1965.
The first generation of what we think of as a cleanroom today at the Willis Whitfield ultra-clean room at Sandia Corporation in the 1960s. With the evolution of the cleanroom and ever tightening restrictions to better control contaminants, the need to control the largest contaminator of controlled environments, humans, led to near-constant cleanroom garment advances.
Cleanroom apparel with proper donning, wearing, and doffing is the key to controlling human-sourced contamination. We share the history that is still unfolding about how cleanroom garments have evolved to reduce particles shed by cleanroom staff while becoming more comfortable to wear and easier to properly don to promote best practices.
As biological and chemical warfare became full-fledged markets in the chemical and pharmaceutical industries, the need to protect not only the environment, but the cleanroom operators had to be protected from hazardous compounds they were exposed to. And as pharmaceuticals became more prevalent, contamination control became an industry in and of itself.
In early efforts to minimize contamination, pharma and chemical industry workers wore wear 100% cotton shirts, pants, and lab coats often in white. Concurrently, hospitals were focused on infection control and wore similar cotton clothing.
The 60s were revolutionary on many fronts from walking on the moon to civil rights to political upheavals. This period brought rapid technological advances in cleanrooms as well with HEPA filtration and the concept of using unidirectional air flow or “laminar flow” that significantly reduced particle contamination. But cleanroom workers were generating particles that introduced risks as they lingered until the filtration system captured them.
In March 1967, the American Association for Contamination Control (A2C2) commissioned the Garment and Laundry Committee to publish “Clean Room Garments and Laundry – A State of the Art Report” that contained references to key requirements for cleanroom clothing:
- stated that Federal Standard 209 required that clothing worn in clean rooms be lint-free.
- declared the US Air Force Technical Order No. 00-25-203 that required garments worn in clean rooms be constructed of a “synthetic fabric with limited linting properties” a standard
- Recommended using fabric from filament Dacron polyester yarn. The primary fabric weaves were:
- taffeta weaves for frocks or lab coats, surgical caps, and boot covers
- herringbone weaves for coveralls.
The Air Force Technical Order had additional detail regarding cleanroom garment specifications:
“Coveralls and smocks should have no pockets, no pleats, no dust-collecting ridges, and no raw edges. All seams should be double-needled and sewn with 100% Dacron continuous filament thread. Both coverall and smock should have adjustable neck bands and cuffs as to allow for tight closure.”
The A2C2 report recommended that all clean room garments be processed and laundered in an environmentally controlled area, a clean room itself. It further specified water washing and dry-cleaning criteria and garment packaging specifications. For sterilization of clothing used in pharmaceutical manufacturing, the report recommended steam, ethylene oxide (ETO), or dry heat processes.
In 1968, the American Society for Testing and Materials published ASTM F-51, “Standard Test Method for Sizing and Counting Particulate Contaminant in and on Clean Room Garments.” This publication has withheld the test of time as with minor editorial changes it was reapproved in 1989 and again in 2007 which as of this writing is the last edition available. The ASTM F-51 test method counts particles larger than five micrometers (μm) and fibers. Clean room industries specified selection of clean room apparel that met Class A particle cleanliness defined as <999 particles larger than five μm and <10 fibers per 0.1 square meter of fabric.
As cleanrooms began partnering with commercial clean room-based laundries to implement the recommendations, the A2C2 Garments and Laundry Committee further clarified its 1967 report in 1969 to add detailed requirements for water washing, dry cleaning, and packaging. The updated report asserted that “No item of clean room clothing should be issued [to cleanroom workers] as received from the manufacturer. It must be laundered first to remove all loose threads and other contaminants possible to adhering to the surface.”
As the 1960s gave way to the polyester (more on that in a moment), bell-bottoms, disco, cultural change, and economic trials of the 1970s, more and more industries were adopting not only cleanroom concepts of contamination removal, but also garment specifications that prevented contamination from humans from being introduced.
With the invention of nonwoven fabrics, not only was the way paved for the ubiquitous polyester fashion of the ‘70s but also for disposable clean room apparel. DuPont developed a flash-spun bonded polyolefin material that proved to be durable and resistant to chemicals and liquid splash and was air-impermeable. This invention called Tyvek made it possible to produce sterilizable garments for pharmaceutical clean room use.
Additional advances in clean room garments began to appear:
- Cleanroom boots were developed because coveralls often did not extend over shoe covers allowing particles to shed from inside the coveralls into the controlled environment.
- Hoods were developed for to protect the critical environments from hair including facial hair.
- The first polyester clean room fabrics with carbon yarns (Kanebo, EV-Guard and Selguard) were developed to dissipate static electricity for industries such as the microelectronics, semiconductor, and aerospace industries.
In the 1980s, members of the Institution of Environmental Science (IES) and industry leaders came to a consensus that “cleanroom” in recognition of the unique filtered, pressurized controlled environments being adopted globally.
By 1987, the IES absorbed the A2C2 Garments and Laundry Committee. During that year, the committee wrote the tentative recommended practice IES-RP-CC-003-87-T, “Garments Required in Clean Rooms and Controlled Environmental Areas” and in October 1989 as IES-RP-CC-003-89, “Garments Required in Cleanrooms and Controlled Environmental Areas.” This recommended practice included the ASTM F-51 test, as well as the Helmke tumble test (see video for example of this test), particle containment test and extractables test for cleanroom garments.
This recommended practice became the basis for the manufacture, cleaning and testing of cleanroom garments. Its 2011 revision, IEST-RP-CC003.4: “Garment Considerations for Cleanrooms and Other Controlled Environments” is still used today.
In the 1980s, W.L. Gore and Associates, Inc., developed Gore-Tex. It is a laminate comprised of polytetrafluoroethylene membrane with a pore size of 0.2 μm bonded to a layer of woven polyester and carbon ESD yarns. This fabric woven with carbon yarns in a grid pattern dissipated tribo-charging so it was used primarily in the semiconductor and microelectronics industries until the late 1990s.
Cleanroom clothing constructed from high-density taffeta without ESD yarns began being used by pharmaceutical and medical device manufacturers. As static discharge became a bigger issue in the pharmaceutical and medical device industries, they also changed to high-density ESD stripe fabrics.
Cleanroom gloves took another leap in innovation during this time with the introduction of disposable gloves made of nitrile. Not only did these gloves provide an alternative to the use of latex that cause allergic reactions in many, but also, they are more chemical resistant paving the way for chemo-rated gloves. Best Manufacturing Company brought this innovation to use in 1991.
Other cleanroom innovations from the 90s included:
- Burlington Industries’ high-density ESD stripe (C-3) and grid taffeta-weave fabrics (Maxima ESD)
- Precision Fabrics Group’s (PFG) use of suffusing with a durable antimicrobial (Integrity 2000) and Teflon shielding (Integrity 1800).
These fabrics’ innovations were reduced permeability with a smaller pore size, durable polyester-carbon ESD yarn, and lightweight more comfortable taffeta weave.
These new fabrics could be sterilized by gamma irradiation which was far superior to the ETO and autoclave steam sterilization methods that up until then had been standard. The 24-hour out-gassing for ETO-sterilized Tyvek disposable garments and 10–15% shrinkage and wrinkled appearance of autoclaved steam sterilized garments hastened adoption of gamma irradiation as the preferred disposable cleanroom garment sterilization method.
During this period of cleanroom garment evolution, undergarments made from 100% polyester non-shedding material replaced the shedding 100%-cotton scrubs worn under coveralls, hoods, and boots in stricter ISO Class 3, 4 and 5 cleanrooms.
Ever innovating DuPont developed its flame-resistant meta-aramid Nomex filament yarns for use in garments for industrial cleanroom requiring flame-resistance as well as for firefighter garments. Burlington Industries and Stern & Stern manufactured garments for these industries using DuPont’s m-aramid Nomex material.
In 1999, a US Patent (filed 1997) was awarded for a “Cuffed and Folded Garment Package and Method of Forming Same to Prevent Contamination”. This focus on preserving sterility during the donning process would generate many innovative changes to cleanroom manufacturing and packaging.
By 2000, the major cleanroom garment laundry facilities were ISO 9001-registered.
In 2003, the Institute of Environmental Sciences and Technology published IEST-RP-CC003.3, “Garment Considerations for Cleanrooms and Other Controlled Environments,” aiming to revise and standardize the manufacture, cleaning, and testing of cleanroom garments for the 21st century. Key points: Fabrics recommended were high-density ESD reusable fabrics and other non-woven fabrics for disposable cleanroom garments.
Also recommended were polyester-based materials used in their manufacturing processes such as thread, zippers, bootstraps, and other ancillary components.
Use of silicone in the manufacture of cleanroom garments was not recommended because of the potential for airborne molecular contamination.
Detailed and standardized precision laundering and packaging guidelines were specified. These The recommendations were based on an inter-laboratory testing cycle where 3 individual labs and 3 laundries independently evaluated the same 10 cleanroom garments using the revised Helmke tumble apparatus and procedure to determine limits for garment cleanliness at both 0.5 μm and 0.3 μm.
Quality management systems were recommended.
USP chapter 797 outlined garbing requirements for pharmaceutical cleanrooms focused on low-linting and sterile apparel as well as donning and doffing. The set of guidelines was proposed in 2003 and published in 2004, then later 2007 revisions were adopted in 2008. This revision remains in effect despite a 2015 proposed revision that received more than 10,000 comments and a 2018 revision. The intended publication date for the revision was December 2019, but appeals have held this publication to date (March 2022). Leaving the specific procedures to individual facilities and their enforcement to state agencies, the guidelines have been slow to be adopted. Many compounding pharma cleanroom facilities indicate that cost of implementation is the biggest factor to compliance.
Did you know that dogs work in cleanrooms? A US Patent was awarded in 2011 (filed in 2008) for a “Canine Cleanroom Suit”.
Though scientific literature started mentioning risks of handling hazardous drugs (HDs) as far back as the 1960s and Europe started evaluations of HD handling when they discovered residues in nurses’ urine, it took 50 years for USP chapter 800 to be proposed. Based on reports and papers by OSHA, a 2004 NIOSH alert, EPA, ONS, the Joint Commission, and others, the guidelines aimed primarily at protecting cleanroom and healthcare workers from exposure to HDs from their receipt through all phases of handling to cleanup, were drafted in 2010.
The final USP 800 draft was not released until 2016 and the original 2018 final draft date was postponed attempting to coincide with the USP 797 revision that remains locked in appeals today.
But nearly a decade after its first proposal, on December 1, 2019, the USP 800 guidelines were published.
While adoption is occurring slowly, the good news is that most of the technologies for cleanroom clothing materials and construction techniques were already in place.
Cleanroom clothing advances over the past decade in the bio/pharma industries have focused on garment and packaging design that improve proper donning and doffing to protect the critical environment and the wearer. Better design also leads to improved productivity as it reduces the amount of time required to perform compliant aseptic gowning and it reduces the amount of training time required. In addition, better design results in more comfortable cleanroom clothing reduces operator error.
By 2019, the global cleanroom industry was a >$12 billion industry with more than 22,000 cleanrooms worldwide. 60% are electronics/semiconductor facilities with just under 40% ISO 5-9 level bio/pharma facilities.
Studies such as the “16th Annual Report of Biopharmaceutical Manufacturing Capacity and Production, BioPlan Associates Inc. April 2019” show that the market should continue to expand for decades.
Biologics industries such as cell and gene therapy, personalized medicine, viral vector gene therapies manufacturing, growth of the biologics sector, sterilized pharmaceutical formulations, and medical device manufacturing are growing rapidly.
Plus, more stringent, and more often enforced, regulations will buoy growth. The projected growth rate is 8-10% despite advances that are enabling greater efficiency that result in smaller cleanrooms and fewer cleanroom techs required.
USP 797 and USP 800 will become more stringently adhered to, and the helpful revisions of USP 797 that have been on hold due to appeals since 2019 should aid in more cleanrooms complying and more advances in cleanroom clothing technology.
Cleanrooms and the apparel worn in them have been evolving for decades. The variety of styles of apparel have also evolved to improve compliance with the many controlled environment standards and guidelines by making them with better materials and processes and making them more comfortable and easier to properly don and doff.
Our cleanroom experts are here to guide you to meet your protocols, avoid common compliance issues, and provide free samples so your team can try before you buy.