The ISO 14644-1 standards were introduced in 1999 due to the need to have a harmonized standard for cleanroom classification and testing. They replaced the US Federal Standard 209E standards. The ISO 14644-1 deals with the classification of air cleanliness in cleanrooms and other controlled environments associated with the cleanroom. The classification is based on the concentration of airborne particulates.
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It is applied to a number of industries such as pharmaceutical, healthcare, medical device production, aerospace production, and food production. The ISO 14644-1 Standard is very common in electronics and pharmaceutical production.

There are specific requirements that a cleanroom or clean zone has to meet during periodic tests to prove compliance with the 14644-1 classification. One of the requirements is that cleanrooms should have the capacity to monitor critical parameters and set action and alert alarms. These risk management protocols allow for the establishment of periodic testing schedules for classification.

The air cleanliness in a cleanroom by particle concentration is usually defined by three states of occupancy. They include:

• As-built: They are the cleanest as they don’t have any equipment or human traffic. They are empty cleanrooms that are fitted with running filter systems but yet to be used.
• At-rest: Equipment and products have been added to the room and there’s human access. But at-rest cleanrooms are yet to undergo testing and have a rating of ISO 6.
• Operational: Cleanrooms become operational once they have been tested for performance requirements, benchmarked, and documented. They are used for a given purpose with equipment present and human access given. These are the dirtiest types of cleanrooms as processes and people introduce contaminants.

​The classification of air cleanliness in cleanrooms is summarized in the table below:

Source: ispe.org
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The classification only considers particle populations with cumulative distributions that meet the lower limit for particle sizes. They usually range from 0.1 µm to 5 µm. Light scattering airborne particle counters (LSAPC) are often used to determine the concentration of airborne particles.

It is important to note that the ISO 14644-1 doesn’t cater to the classification of particle populations that don’t meet the lower threshold for particle size range 0.1 µm to 5 µm. A separate standard is used for concentrations of ultrafine particles that are smaller than 0.1 µm. The ISO 14644-1 is also not used for characterizing chemical, physical, viable, radiological, or any other nature of airborne particles.

Cleanrooms are very important in pharmaceutical manufacturing. They provide a controlled area with specific levels of air particles and contaminants that don’t interfere with product safety. Pharmaceutical products are very sensitive and airborne particles can easily contaminate them. The chemicals used can also be too hazardous for production to be done in an open environment.

Setting up a cleanroom for pharmaceutical operations requires a facility to adhere to the International Organization for Standardization (ISO) standards and guidelines. (see more on ISO Cleanroom Classifications) Facilities need to ensure that all their needs are addressed during the design phase for a cleanroom. Some of the things to consider when setting up a cleanroom for pharmaceutical operations include:
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• HEPA filters that are able to filter particles that are as small as 0.3 microns. This ensures that the employees working in the cleanroom have a constant supply of fresh air.
• Proper ventilation for maintaining air quality and replacing process exhausts. As it’s energy-intensive, you’ll need extra space for cooling units, noise suppressors, larger air passageways, large intake and exhaust stacks, and a backup generator.
• Static air pressure that’s higher than the atmospheric pressure to prevent infiltration by wind. Airlocks are used to prevent pressure fluctuations.
• Stable temperature and humidity for comfort and to prevent corrosion of surfaces.
• Unrestricted airflow to prevent turbulences which can result in the movement of particles and contamination.
• Measuring equipment to help in maintaining cleanliness, temperature, humidity, airflow, and particle count at the appropriate levels.
• Electrostatic discharge to prevent potential damage caused by an electrical charge from movements.
• Good lighting for efficient operations.
• Future-proofing for possible expansions or process change.
• Use materials that don’t shed, break, or crack easily and can also be easily cleaned.
• Showers and laundry facilities to be used for decontamination. You might also want to consider hazardous waste treatment.
• Personal protective gear and separate entrances and exits to avoid contamination by hazardous materials. Consider special treatment of waste air and using negative air pressure systems too.

There are many elements you’ll have to take into consideration when designing a cleanroom for pharmaceutical operations. You will also have to consider the amount of space you have and how many pieces of equipment you’ll need for your operations. Ensure that you discuss all these with your cleanroom contractor.

After setting up your cleanroom, it will need to be validated and certified for use in pharmaceutical manufacturing. This means that a number of tests will be undertaken and regular monitoring and revalidation also done to ensure the standards are up to date.
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While certifications will depend on your geographic location, the International Standards Organization (ISO) standards are generally accepted and widely used at the moment.

​Once the cleanroom has been validated and certified fit for operations, you will need to maintain it with the utmost care to preserve its integrity. Some of the ways of doing this include minimizing the risk of contamination, limiting access to only trained and authorized personnel, regularly cleaning and undertaking maintenance activities, and periodically updating it to the latest industry standards.

Cleanrooms provide a controlled environment for sensitive scientific research and manufacturing processes to take place. They are designed in a way to minimize the introduction, generation, and retention of particles inside the room. It requires an incredible amount of technology to create and maintain such levels of cleanliness. Cleanrooms have air filtration systems that completely change the air several times per minute and reduce the chances of harmful airborne particles getting into products.
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Proper cleanroom gowning and cleaning procedures are needed to ensure consistent cleanliness and contamination control. While procedures vary depending on the cleanroom classification and application, there are general basics that can help in keeping the environment clean. This guide will look at the cleanroom procedures for reaching and maintaining cleanliness.

The cleanliness of a cleanroom doesn’t end with the disposal of used gowns and garments upon exit. The cleanroom itself has to be cleaned. Here are the guidelines for cleanroom cleaning:

• Only specified cleaning agents should be used in cleaning the cleanroom. Keep off general non-cleanroom cleaning agents.
• Surfaces such as benches, cleanroom walls, and floors should be scrubbed using deionized water.
• Avoid using rags, scrubs, and powders to clean cleanrooms. Instead, use cleanroom mops made from woven polyester that don’t tear up or shed during cleaning.
• Use designated water control, deep-drawn seamless buckets, and an autoclave-ready multi-bucket mopping system that has non-marring wheels.
• Use distilled water to damp mop the cleanroom floors daily before the normal work shifts begin then vacuum-dry the floors.
• Damp-mop the floors weekly using distilled water, a cleanroom detergent, and a HEPA filter vacuum.
• Ensure that you vacuum the walls on a daily basis.
• Use distilled water and a damp cleanroom sponge to wipe the walls before vacuum drying each week.
• Wash and wipe dry the cleanroom pass-throughs and windows every day using 70% IPA wipes. The wipes should be lint-free.
• Ensure that you vacuum the ceilings on a daily basis.
• Use distilled water and a damp sponge to wipe the ceilings each week before vacuum drying.
• Whenever necessary, use distilled water and detergent to wash the ceilings in order to remove deposits. Sometimes deposits are formed depending on the application of the cleanroom.
• Besides the floors, all the other daily cleaning tasks should be carried out during the normal work shifts.
• Use distilled water and a damp sponge to wipe overhand light lenses and troffers before vacuum drying.
• Always change the cleanroom sticky mats whenever necessary.

Not all cleanrooms use the procedures listed for their gowning and cleaning guidelines. As mentioned, that depends on the classification of the cleanroom and its application. This guide is only intended to give you an idea of how to keep your cleanroom from getting contaminated and help you get started. These are simple tasks but their benefits to the maintenance of cleanroom standards are significant and compounding.

Production facilities and laboratories need to observe the highest standards of cleanliness. A cleanroom is an enclosed area of a facility designed to maintain extremely low levels of contaminants such as vaporized particles, airborne organisms, and dust. Cleanrooms are used for scientific research and the production of precision electronics, pharmaceuticals, and other highly sensitive products.

Some of the industries where cleanrooms are commonly used include:

• Life sciences
• Military and aerospace research
• Computer server holding
• Computer manufacturing
• Medical device production
• Food processing

Cleanrooms have specific ISO class code descriptions that provide secure environments through controlled air filtration and protective guidelines. That reduces the possibility of large particulates interfering with critical process manufacturing or the possibility of product contamination. Cleanroom classifications also require facilities to maintain positive pressure as long as the cleanroom is operational. It prevents the flow of contaminated air back into the environment by continuously flowing filtered air to less-clean spaces.

A clean environment is a requirement for most industries. Cleanrooms are among a production cycle's most important components, as they enable processors and manufacturers to work in safe environments and put out high-quality products but different industries have different criteria for cleanliness. Therefore, cleanrooms also have varying levels of tolerance for particles.

The classification of these tolerances is done in line with the International Standards Organization (ISO) guidelines. However, there are basic requirements that every cleanroom should meet. They include:

• Internal surfaces: Every surface in the cleanroom should be smooth and impenetrable by microorganisms. They should also be strong enough not to crack or shatter besides being easy to clean. The materials for the surfaces shouldn't create flakes or dust.
• Airflow: A cleanroom's airflow system should be effective at circulating particles out of the room. Facilities usually use air filters to clean out contaminants such as vapor, moisture, or particulates. Air can be recirculated after cleaning or fresh air pumped into the cleanroom as a replacement.
• Employee access: The number of people allowed into a cleanroom should be strictly controlled and only specially-trained personnel given access. Managing people who go in and out of a cleanroom is given the highest priority as human beings are the largest source of contaminants.

The level of cleanliness in cleanrooms is quantified by the number of particles in every cubic meter at a predetermined molecule measure. Class 1 facilities have the lowest level of contaminants while Class 9 facilities have the highest. The typical urban outdoor air has 35,000,000 particles per cubic meter at a 0.5-micrometer size range. This is the same as an ISO 9 cleanroom. An ISO 1 cleanroom contains 12 particles per cubic meter at a size range of 0.3 micrometers. At 0.5 micrometers, an ISO 1 cleanroom doesn't have any particles.

The classification of cleanrooms is usually done according to the size and number of particles permitted per volume of air. Cleanrooms should not exceed a particulate count as specified in its air cleanliness class. Until 2001, the Federal Standard 209E was used before it was replaced with the ISO 14644-1. The federal standards used cubic feet in measuring the size while the ISO standards rely on cubic meters. As a result, Class 1 was the cleanest according to federal standards but corresponded only to ISO 3 under the ISO 14644-1 standards.

See the table below for a summary of the classification of cleanrooms:

Cleanrooms are regularly tested and inspected to guarantee their effectiveness. The higher a cleanroom's classification, the more inspections it undergoes but the inspections are typically connected to compliance testing which is done once or twice per year.

The testing and characterizing of cleanroom performance are done at three different levels of conditions. They include:

• As-built: This refers to empty cleanrooms with running filter systems. The cleanroom, in this state, doesn't have any workers or equipment. It's in its cleanest state as it has never been used.
• At Rest: A cleanroom is in the At Rest state once pieces of equipment and products are added to it. These kinds of cleanrooms are yet to undergo testing but have always had human access. An At Rest cleanroom is rated ISO 6 at best since it isn't as clean as the first type (as-built).
• Operational: Cleanrooms become operational once they have been tested for performance requirements, benchmarked, and documented. They are used for a given purpose with equipment present and human access given. These are the dirtiest types of cleanrooms as processes and people introduce contaminants.

Industries such as pharmaceutical labs, specialist manufacturing facilities, and testing booths generally use ISO 7 cleanrooms. They are designed to prevent the contamination of processes going on inside the room.

The minimum standards for ISO 7 cleanrooms include:

• An air change rate of 60 to 90 per hour
• Mandatory testing every six months according to ISO 14644-2 guidelines
• A separate gowning room
• 352,000 particles per cubic meter at 0.5μm
• HEPA filters

The ceiling coverage of an ISO 7 cleanroom is between 15 and 25%. ISO 7 cleanrooms are mostly used to prepare solutions that need filtering, production processing, and specialist component handling.

ISO 8 cleanrooms are mostly used for aerospace product development, cosmetic lines, bottling lines, pharmaceutical compounding, electronics production, and production of medical devices.

Unlike ISO 7 cleanrooms, ISO 8 cleanrooms don't require testing for certain particle sizes as they either have very high or low concentration levels for testing. However, the particle sizes can't be zero. Particles that are smaller than 0.5 µm aren't usually considered while concentration levels for particles that are less than or equal to 0.5 µm should be less than 3,520,000.

The air change rate for a class 8 cleanroom should be 5 to 48 every hour with a 5-15% ceiling coverage. An ISO 8 cleanroom is also required to be fitted with HEPA filters.

For the other classes of cleanrooms, the rate of an air change per hour is as follows:

• ISO Class 1: 500-750, ceiling coverage of 80-100%
• ISO Class 2: 500-750, ceiling coverage of 80-100%.
• ISO Class 3: 500-750, ceiling coverage of 60-100%.
• ISO Class 4: 400-750, ceiling coverage of 50-90%.
• ISO Class 5: 240-600, ceiling coverage of 35-70%.
• ISO Class 6: 150-240, ceiling coverage of 25-40%.

Air change rates help facilities determine the design and performance criteria for a cleanroom's air system. The total air change rate, flow pattern, and efficiency of the exchange have an impact on the cost and performance of a cleanroom.

Differential pressure refers to pressure deviation between two points in different pressure systems. Different cleanroom classes require a specific number of air changes per hour and differential pressure is key to maintaining a particular classification. It ensures that the correct operation and efficiency of a cleanroom are met.

Europe, Australia, and some Asian countries have a set of standards that cleanrooms used for the manufacture of sterile medicinal products should adhere to. The standards dictate that sterile products should be manufactured in clean areas with entry into the areas by personnel and materials through airlocks. Filters should efficiently clean the air passing into the area.

Still, it’s impossible to completely eliminate contamination in a cleanroom; these measures only mean it’s controlled to acceptable levels. That is done in the following ways:

• The internal surface: Every surface in the cleanroom should be smooth and impenetrable so that it doesn’t generate its own contaminants such as dust or corrosion. That also makes it easier to clean the surface when surfaces aren’t prone to cracking, shattering, or creasing.
• Cleanroom air control: Cleanrooms need a lot of air to stay clean. Air systems circulate air through the cleanroom, keeping the temperature and humidity stable while removing contaminants. The air system recirculates the air after the contaminants have been filtered out. The more air a cleanroom has, the faster the cleaning is. Cleanrooms are usually pressurized by allowing in more air than the amount that goes out.
• Operating a cleanroom: Operating a cleanroom properly helps to maintain its air quality. The amount of contamination from manufacturing operations should be minimal and the cleanroom should be regularly cleaned through the proper laid-down guidelines. Maintenance of the equipment and air control systems should also be regularly undertaken. Most importantly, only trained personnel should have access to the cleanroom.

Manufacturing operations are usually divided into those that are aseptically conducted and those that require the product to be sterilized. Sterile production requires certain characteristics to minimize the risk of contamination of the materials or products. For a cleanroom to meet in-operation conditions, it must first achieve specific levels of cleanliness in at-rest occupancy rates.

Cleanrooms are usually graded depending on the level of manufacturing for sterile products. The grades are as below:

• Grade A: These are cleanrooms used for high-risk operations such as stopper bowls, filling zone, open ampoules and vials, and creating aseptic connections. Laminar airflow workstations provide these conditions in normal situations by providing a homogeneous airspeed of around 0.45 m/s at the working position. Grade A is the cleanest and is used for sterile operations.
• Grade B: This grade provides a background environment to enable aseptic preparation and filling for some grade A zone items.
• Grade C: Grade C cleanrooms are used to perform less critical activities needed for the non-critical manufacturing stages. They are mostly used for support and packing operations.
• Grade D: Similar to Grade C and used for the less critical operations.

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The grades can be related to ISO classes. ISO classes are basically the level of cleanliness of a cleanroom based on the number of particles of a given size per cubic meter. ISO 8 is usually the base level. Cleanrooms used for sterile manufacturing processes need to achieve ISO 5 level of cleanliness. Only electronics manufacturing requires classes above ISO 5.

The International Organization for Standardization (ISO) is a global federation of national standards bodies that develops international standards. Neslo Manufacturing adheres to ISO standards when manufacturing cleanroom wall systems.  This is done through ISO technical committees in which member bodies with interest in the subject sit on. The organization also partners with other international organizations, government institutions, and non-governmental organizations to carry out its mandate. For example, ISO collaborates with the International Electrotechnical Commission (IEC) for electrotechnical standardization. 

The technical committees prepare drafts of international standards then circulate them to member bodies for voting. A 75% threshold is required for a draft to be published as an international standard.

The ISO 14698-1 was first published in 2003. It describes the basic methodology and principles needed in a formal system to assess and control biocontamination for cleanrooms. This helps in monitoring biocontamination in risk zones in a reproducible way and putting in place the necessary control measures to mitigate the risk.
The aim of ISO 14698-1 is to promote hygienic practices.

In order to assess and control biocontamination, formal systems rely on the following principles:

• Identification of potential hazards to the production process or the product and assessment of the likelihood of their occurrence. Prevention or control measures also have to be identified.
• Designation of risk zones and the determination of controllable factors such as procedures and conditions that eliminate or reduce the chances of the hazards occurring.
• Establishment of control limits.
• Establishment of a schedule for monitoring and observation.
• Establishment of corrective actions when certain trigger conditions are met.
• Establishment of procedures, including supplementary procedures and tests, to verify the effectiveness of the system.
• Establishment of procedures for training personnel.
• Establishment and maintenance of appropriate documentation for the laid-down guidelines and procedures.

For biocontamination control to be possible, there’s a need for facilities to establish a formal system that allows for the timely detection when conditions deteriorate. The formal system should be tailored to the facility’s needs, the field of application, and specific conditions. It should also include a proper training program for cleanroom personnel besides establishing monitoring guidelines that can be easily implemented to minimize the risk of contamination.

Examples of sources of bio-contaminants include liquids, textiles, surfaces, and air.

Furthermore, facilities are required to put in place biocontamination alerts and action levels depending on the classification of the risk zones and field of application. The facility should rely on data to establish and periodically review alert and action level baselines. When the alerts are triggered, a facility will need to undertake immediate intervention. This includes investigations on the cause and performing corrective action.
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While the ISO 14698-1 addresses viable biocontamination, it isn’t as widely used as the ISO 14644. This is because it doesn’t give specific requirements for application and is quite vague. Other monitoring guidance offers great detail for performing environmental monitoring. The ISO 14644 is more specific and covers most of the physical aspects of cleanroom operations, including counting of particles. There’s no mention of ISO 14698 in any GMP guidance but a review of the standard has already been initiated by the technical committee.