Aseptic Area and Clean Area Classification

Aseptic Area and Clean Area Classification



• Designing of aseptic area

• Laminar flow equipment

• Sources of contamination

• Prevention of contamination

• Clean area classification

Intended learning objectives

At the end of this lecture, the student will be able to

• Describe the design of a clean room

• Identify the types of laminar flow equipments with their
salient features

• Recognize the sources of contaminations in clean room

• Classify clean room

• Suggest measures to overcome contamination in clean rooms

Aseptic Area and Clean Area Classification

Aseptic Area

• A clean room is a room with environmental control of

– Particulate contamination

– Temperature and humidity

– Constructed and used in such away as to minimize the introduction, generation and retention of the particles inside the room

Design of Aseptic Area

• The design of aseptic area will be discussed under the following headings:

  Size of aseptic room

  Walls and ceilings

  Floors and drains

  Doors, windows and fittings




  Disinfection and sterilization

  Microbial checks


• The proper size of an aseptic room depends on the maximum number of people which are going to use it

• The maintenance cost can be reduced if the aseptic room is a bit smaller in size

• The walls and the ceiling of the room should be of reasonable size so that it can be cleaned in routine without any difficulty


• The windows in the room are a source of dust particles which may enter and contaminate the atmosphere

• In order to provide good light in the aseptic room, glass panes should be used

• Ventilation should be provided by laminar air flow system


• The entrance to the aseptic room should be through an air-lock with double doors about 1 meter apart

• This is necessary to prevent a sudden in –rush of air when the door is opened

• The outer door is opened only when it is confirmed that the inner door (which opens into the aseptic room)is closed. For this purpose a small window is needed in the outer door

• The inner door is opened when the outer door is closed

Surface Materials

• The floors, walls and the bench tops of an aseptic room must be smooth, resistant to chemicals and easily cleanable

• The floor of the aseptic room needs frequent washing to prevent the accumulation of dirt

• The floor should be built with Terrazzo (mixture of cement and crushed marble), Linoleum (heavy grade) and plastics

• The walls and ceiling should be provided with tiles or coated with hard glass paint or smooth plaster or covered with plastic laminated boards

• The working table tops should be made of stainless steel or plastic laminates so as to avoid accumulation of dust


• It includes the removal of microorganism, control of humidity and temperature and provision of fresh air

• The clean air free from microorganism can be produced by mechanical filtration or electrostatic precipitation


• The electric supply is needed for lighting and functioning of equipment and machinery

• The switches and sockets should be flush fitting and have finger plates of plastic

• As far as possible, most of controls should be outside the room

Gas supply is needed for burning of burners.Gas cocks may be on the walls or at the back of the bench.

Vacuum arrangements for clarification and bacterial filtration.

Disposal of waste:- In order to control the dust, such arrangement should be made that majority of the pipes and fitting get hidden in the walls of the room or these are properly covered


• Furniture such as working benches, chairs, trolleys and screens are used in an aseptic room

• The furniture should be such that there is the least number of undesirable dust retaining cavities

HEPA Filters

• The key component is the High Efficiency Particulate Air (HEPA) filter that is used to trap particles that are 0.3 micron and larger in size

• All of the air delivered to a cleanroom passes through HEPA filters, and in some cases where stringent cleanliness performance is necessary, Ultra Low Particulate Air (ULPA) filters are used.

Gowning in Clean Rooms

• Lab coats and hairnets

• Extensive as fully enveloped in multiple layered bunny suits with self-contained breathing apparatus

• Cleanroom clothing is used to prevent substances from being released off the wearer’s body and contaminating the environment

• The cleanroom clothing itself must not release particles or fibers to prevent contamination of the environment by personnel

Proper gowning order

– Hair cover

– Hood

– Shoe covers

– Coverall

– Gloves

– Face mask

– Safety Glasses

• Cotton garments shed fibers. Hence, not used

Cleaning and disinfection

• Cleaning and disinfection procedures are used for the removal of microbial and particulate contamination

• Cleaning agents are the alkaline detergents, non-ionic and ionic surfactants

• Different types of disinfectants should be employed in  rotation to prevent the development of resistant strains of microorganisms

• Different concentration of quarternary ammonium compounds, sodium hypochloride, ethanol and formaldehyde solutions are used as disinfectants in cleaning area

• Cetrimide or chlorhexidine in 70% alcohol are suitable for use as skin disinfectants

Air Supply

• The air supplied to a clean room must be filtered through high efficiency particulate air (HEPA) filters

• The HEPA filter must be positioned at the inlet of the clean room and the prefilter may be fitted upstream of the HEPA filters to prolong the life of final filter

• HEPA filters are used in the construction of vertical and horizontal laminar air flow bench

• The air filtered from the laminar air flow is claimed to be 99.97% free from the microbial contamination

• These filters are supported to provide class 100 air and they should be certified every 6 to 12 months

• Air quality is evaluated using settle plates, microbial air sampler or by particle counters

Cleanroom Air Flow


• Cleanrooms maintain particulate-free air through the use of either HEPA or ULPA filters employing laminar or turbulent air flow principles

• Laminar, or unidirectional, air flow systems direct filtered air downward in a constant stream

• Laminar air flow systems are typically employed across 100% of the ceiling to maintain constant, unidirectional flow

• Laminar flow criteria is generally stated in portable work stations (LF hoods), and is mandated in ISO-1 through ISO-4 classified cleanrooms

Laminar Flows

Laminar air flows can maintain a working area devoid of contaminants. Many medical and research laboratories require sterile working environments in order to carry out specialized work.

1.   Vertical laminar air flow bench

2.  Horizontal laminar air flow bench

Why Laminar Flow Cabinets?

• Laminar Flow Cabinets create particle-free working environments by projecting air through a filtration system and exhausting it across a work surface in a laminar or unidirectional air stream

• They provide an excellent clean air environment for a number of laboratory requirements

• The process of laminar air flow can be described as airflow where an entire body of air flows with steady, uniform velocity

• Laminar Flow Cabinets work by the use of in-flow laminar air drawn through one or more HEPA filters, designed to create a particle-free working environment and provide product protection

• Air is taken through a filtration system and then exhausted across the work surface as part of the laminar flows process.

• Commonly, the filtration system comprises of a pre-filter and a HEPA filter      

• The Laminar Flow Cabinet is enclosed on the sides and constant positive air pressure is maintained to prevent the intrusion of contaminated room air

Types of Laminar Flow Cabinets

Horizontal Laminar Flow Cabinets

• Horizontal Laminar Flow Cabinets receive their name due to the direction of air flow which comes from above but then changes direction and is processed across the work in a horizontal direction

• The constant flow of filtered air provides material and product protection.

Vertical Laminar Flow Cabinets

• Vertical Laminar Flow Cabinets function equally well as horizontal Laminar Flow Cabinets with the laminar air directed vertically downwards onto the working area

  The air can leave the working area via holes in the base.

Vertical flow cabinets can provide greater operator protection

Cleanroom Classifications

• Cleanrooms are classified according to the number and size of particles permitted per volume of air

• Large numbers like “class 100” or “class 1000” denote the number of particles of size 0.5 mm or larger permitted per cubic foot of air

Types of Clean Room Contaminants

• Air

• The production facility

• The production personnel

• Process water and chemicals

• Process gases

• Static electric charge

Particulate Contamination

Source of particulate contamination                             



dust and aerosols in the air


The operator

hair, skin flakes, bacteria, and clothing fibers, finger prints


The equipment

flecks of dried processing chemicals, dust, paint flakes, fiber dust,
wiper dust


Glass or plastic dust

fragments of glass or plastic from when they are cut


Dirty solvents

particles in water, cleaning solvents, and the like


Bacteria Cleanroom Contamination

• Bacteria are a natural part of the environment and may act as either a chemical or a particulate contaminant

• Clean environment minimizes the number of bacteria that are initially in the air

• Sneeze or a cough will generally put both bacteria and aerosol particles into the air

• Bacteria are on everyone’s skin and scratching exposed skin will place both skin flakes and bacteria into the air

Sources of Cleanroom Contamination

• The air in the facility

• The personnel in the facility (including things brought into the facility with them).

• The water used within the manufacturing process

• The chemicals and gases used in the process

• Static electric charge

• The production facility and equipment in the facility

Prevention of Contamination


• Large fraction of the particles in the air in a cleanroom are removed via HEPA (high-efficiency particle attenuation) filters

The Personnel

• Cover up as much as possible with low contamination clothing

Water Contamination Issues

• The water used in many cleanroom manufacturing applications is treated to remove the following contaminants:  dissolved minerals and salts, particulates, bacteria and organics

Process Chemical Contamination

• To be delivered in clean, non-corrosive containers, transported ‘cleanly’ and not cross contaminated

Equipment and Consumables used within the Cleanroom

• Must be compatible for used in a cleanroom

• Specialized cleanroom wipes, cleaning equipment and disinfectants will always be used.


• Design of clean room – building materials, walls, size, air handling systems, and HEPA filters

• Laminar air flow cabinets – Horizontal and vertical; employ HEPA filters to filter particulate contaminants from air to provide contamination free air for aseptic procedures

• Sources of contamination – air, personnel, water, chemicals, etc.

• Minimization of contamination – based on the source suitable contamination minimization techniques to be followed

• Clean area classification – Class10, 100, 1000, 10000 and 100000

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