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

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


• 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

  Walls and ceilings

  Floors and drains

  Doors, windows and




  Disinfection and

  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

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 
  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

• 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

• 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

• 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

• 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


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

• 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

• 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 

Vertical flow cabinets can provide greater operator


• 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


Source of particulate



The room itself                                                                                         

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


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

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

Water Contamination

• 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

• 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

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