Better gowning by application of QbD

Aseptic gowns manufactured using Quality by Design principles will reduce costs, increase efficiency and improve patient safety. Jaime Cassar, Category Manager and cGMP aseptic gowning expert at Kimberly-Clark Professional, explains how

Comfort is an extremely important aspect of work performance, improved by clothing that helps maintain consistent body temperature

Quality by Design (QbD) is a concept based on the premise that quality should be planned into every process/product from the very start. This has been adopted by enforcement agencies globally and, as a result, has become a key approach to pharmaceutical quality. By selecting sterile personal protection equipment (PPE) manufactured using QbD principles, quality and sterility assurance managers can promote more efficient gowning and gloving techniques and minimise the risk of infection in pharmaceutical cleanrooms and pharmacies carrying out aseptic manipulation.

Robust drug handling, patient outcome and the health and safety of technicians and clinicians all rely on the creation and maintenance of an aseptic environment. Studies also demonstrate that comfort is an extremely important aspect of work performance, improved by clothing that helps maintain consistent body temperature.1 Ultimately, by reducing risk of infection and introducing PPE that simplifies the aseptic gowning process, quality and sterility assurance managers can improve productivity, help avoid costly errors and safeguard patients’ lives.

A QbD approach to sterile PPE requires a systemic outlook. PPE manufacturers must consider the entire system: from contaminant micro-organism to fully-gowned technician within a quantifiable cleanroom or pharmaceutical environment. Four main risk factors that can be addressed through the application of a QbD approach to sterile clothing design and manufacture are:2

  • Exterior contamination of clothing during sterile gowning
  • Contaminants escaping through gaps between sterile clothing items
  • Contaminants passing though clothing fabric
  • Operator discomfort causing human error

Functional efficiency can be designed into PPE at the drawing board. QbD-led manufacturers tailor aseptic clothing to meet the specific needs of the user.

Hazard reduction

Aseptic gowning is difficult and can take up to 10 minutes. Effective training of new joiners can take up to 30 hours, with a further six hours per week ongoing training. Human error is the number one cause of contamination of aseptic environments. Additional training might help reduce human error during gowning, but simplifying the gowning process through application of QbD principles at the manufacturing stage offers a less costly and more efficient solution.3

The risk of an operator touching the outer surface of the suit during gowning can be greatly reduced through considered folding and packing of the suit

QbD aseptic clothing designs, such as Clean-Don Technology4 from Kimberly-Clark Professional, can reduce risks of contamination by simplifying the gowning process. The risk of an operator touching the outer surface of the suit during gowning can be greatly reduced through considered folding and packing of the suit, clear indication of inside and outside surfaces and safe touch points, and better visual training tools.

Traditionally packed and presented with outer surfaces showing and zip closed, users can find it difficult to unpack and don aseptic gowns without external contamination. By eliminating these difficulties, and further aiding the gowning process by presenting the suit with legs and arms already drawn up, manufacturers can make gowning easier, saving a huge amount of time and money previously associated with a lengthy gowning process and intense re-training.5

Gowning practices are part of every Healthcare Environment Inspectorate (HEI), FDA or cGMP inspection. QbD sterile clothing is a beneficial indicator of cGMP compliance when used in conjunction with a documented and enforced training programme, good training materials, proof that operators have been properly qualified and ongoing monitoring and audit of aseptic gowning compliance.

Minimising gaps

Functional QbD elements that reduce the risk of contamination escaping into an aseptic environment through clothing gaps include: the integration of mask and hood; a well-sealed interface between mask, hood and goggles; use of elastics to eliminate snaps and ties; and material selection aimed at improved breathability and comfort.

People are the most common sources of microbial contamination; there are 1,000,000 microbes/cm2 of skin, the skin sheds on average 40,000 skin cells per minute and 100,000 particles >0.3μm when standing still. When moving, this increases to 10,000,000 particles >0.3 μm per minute. Exhaled air also contains particles and droplets of saliva; there are 1 billion microbes in just 1ml of saliva.5.5

Even if directed away from the gown, exhaled air can result in dissemination of microbe-laden saliva droplets onto external surfaces and the wider environment

While protocols recommend talking as little as possible in an aseptic environment, being human, cleanroom technicians and pharmacists are likely to exchange dialogue throughout their shift. Even if directed away from the gown, exhaled air can be carried by turbulence and the uni-directional downward airflow in an aseptic environment, resulting in dissemination of microbe-laden saliva droplets onto external surfaces and the wider environment.

When shed, human skin particles can be around 10µm to 40µm, but movement and abrasion grinds them down to <1µm. Differences in temperature between the individual and the gown create a higher pressure inside the garment. This microenvironment creates an upward current of air that can travel at nearly 1m/s by the time it has reached the neck and head. More than 100,000 particles of sweat and skin can escape from gaps between the hood and the suit.6

Coupled with a wide spectrum disinfection plan, a QbD approach to aseptic gowning design can control and reduce contamination risk. Integrated clothing that eliminates gaps between garments both reduces the risk of micro-organisms escaping into the environment and simplifies the aseptic gowning process by reducing the number of gowning steps.

Improving barrier performance

Bacterial filtration efficiency (BFE) testing is an established method to quantify the barrier performance of a cleanroom clothing fabric. Sterile clothing manufacturers typically set design specifications at >95%, for example.

Some manufacturers provide a pre-set validation threshold quantifying a fabric’s physical properties, particle release and BFE after increasing numbers of processing and sterilisation cycles. Quality and sterility assurance managers can refer to these in SOPs to specify the maximum number of times sterile gowns can be laundered before being removed from circulation due to a drop in BFE below the product specification. However, such validation studies may not always reflect true fabric performance in particularly stressful environments (see Figure 1).

Figure 1: Bacterial filtration efficiency of sterile clothing. ASTM F2101 test method

A case study measuring the performance of a random selection of sterile cleanroom clothing from an inventory pool of a large injectables manufacturer in the US illustrates the risk of contamination if the BFE of continuously re-laundered gowns is not monitored.7 BFE data was gathered from 24 articles of one particular type of sterile clothing that had undergone processing between 10 and 60 times. The results were consistently below 70%, well below the 99% BFE specification set by the laundry provider.

This scenario can easily be avoided. For tough environments, accuracy of the performance validation threshold can be improved. Some pharmaceutical manufacturers have carried out their own microbial detection studies to determine a lower threshold appropriate to their own sterile environments. However, this ‘quality by inspection’ approach is far less effective than employing QbD.

A QbD approach to sterile clothing will deliver a consistent and high level of BFE across all gowns produced by taking a systemic overview and optimising design production processes and quality controls of the fabric manufacturing, clothing construction, laundry and sterilisation of clothing. A QbD approach to BFE monitoring will incorporate sample testing across every production lot or laundry load and ensure product is not released unless the BFE specification is met. This will assure both BFE conformation and maintenance of other important physical properties such as resistance to fluids, flames, lint and abrasion.

Reducing human error

According to Human Reliability expert Dr Collazo, the most effective way to control human error and address the majority of cGMP deviations affecting the industry is to implement good systems.8 Systems take care of human factors as well as external factors. A study published by the Hohenstein Institute in Germany, demonstrated that operators achieved a reduction of 44% in error rates and increased reaction time by 6% when wearing more comfortable aseptic gowns during focused repetitive tasks.9

QbD cleanroom clothing design helps maintain consistent body temperature and reduce sweat and pressure build-up inside aseptic coveralls

By addressing the user’s level of comfort, QbD cleanroom clothing design helps maintain consistent body temperature and reduce sweat and pressure build-up inside aseptic coveralls. By doing so, it tackles the root cause of contamination.Fabrics that combine both breathability and high filtration efficiency enable heat to dissipate more easily through the gown, while preventing dead skin particles or sweat from passing through. Aseptic clothing made from these materials reduces contamination risk, increases operator comfort and, as a result, improves worker performance rates and patient safety.

QbD sterile cleanroom clothing offers a range of gowning solutions to meet the specific criteria of each aseptic environment. This enables managers to purchase those products that offer the highest levels of comfort while maintaining appropriate hazard protection for each specific environment. Rather than a ‘one-solution-fits-all’ approach, QbD delivers value-added, solutions such as Kimberly-Clark Professional’s new sterile cleanroom clothing and APEX Training.10

In summary, the cost of contamination caused by human error is significant in aseptic environments. Companies can address these errors and their associated costs by purchasing aseptic gowning sold by manufacturers who apply QbD principles to their design, production and after-sales processes. This approach facilitates simpler, more efficient gowning and introduces integrated coveralls using fabrics with greater barrier and sterility assurance and improved comfort. QbD increases functional efficiency and advances the idea of specialised product ranges to suit the particular needs of each environment.

By reducing contamination risk, simplifying gowning and increasing user comfort, QbD PPE minimises human error, improves productivity and maximises profitability and most importantly offers better control of aseptic environments that leads to improved patient outcomes.


1. Longo et al. Minimally Invasive Therapy. 2009; 18:1;20-29

2. Kimberly-Clark Professional white paper: Optimum sterile cleanroom gowning with QbD, J. Cassar, 2014

3. Donning by Design, 2010, D. Larkin

4. KIMTECH Product Brochure

5. Two minute reduction in gowning time for a site doing 100 entries a day into cleanroom equates to saving of 1217 hrs/year (73000 min/year = 2 min/entry x 100 entries/day x 365 days/year.

6. Micron International Training


8. On reducing human error in pharmaceutical and biotechnology manufacturing, Ginette M. Collazo, June 15, 2010

9. Hohenstein Institute;