Surgical site infections (SSIs) are the second most common
cause of hospital acquired infections.
The source of SSIs may be endogenous or exogenous, which
includes surgical personnel ,the operating room environment
(including air), and tools, instruments, and materials brought to
the sterile field during an operation.
By maintaining sterile environment in operation theatre we
can control major part of exogenous infections.
Fumigation is the process by which we can sterilize the
enclosed area by injecting the chemical which will kill or
destroy microbes present in the air.
In 1867 –Dr.Joseph Lister first identifies airborne bacteria and
uses Carbolic acid spray in surgical areas.
He introduced the antiseptic spray to the
operating theatre to disinfect the atmosphere
around the operating table.
It worked by heating water to boiling point in
the upper chamber of the instrument, so that
steam was forced out of the tube on the right.
The carbolic acid in the glass container was
drawn up and mixed with the steam before
being emitted into the air.
Fumigation is a process of gaseous sterilisation which is
used for killing of micro-organisms and prevention of
microbial growth in air, surface of wall or floor.
It is generally used in the pharmaceuticals, operation
theatres, hospitals, hotels and offices and wherever
Method of fumigation completely fills an area with
gaseous fumigants to suffocate or poison the microbes
& pests within.
A gas at room temperature, formaldehyde is colorless
and has a characteristic pungent, irritating odor.
When dissolved in water, formaldehyde forms a hydrate
A saturated water solution, that contains about 40%
formaldehyde by volume or 37% by mass, is called "100%
A typical commercial grade formalin may contain 10–
Formaldehyde at approximately 5% in a
solution with water is used as a fumigant and
disinfectant in hospitals.
Formoldehyde kills microbes by alkylating
the amino acids and sulfydral group of
proteins and purine bases.
In order to be effective, the gas has to
dissolve in the film of moisture surrounding the
bacteria, for this reason relative humidities in
the order of 75% RH and temperature above
Electric Boiler Fumigation Method: For Each 1000 cu.ft
500ml of formaldehyde added in 1000ml of water in an
electric boiler. Switch on the boiler, leave the room and
seal the door. After 45 minutes switch off the boiler
without entering in to the room.
Potassium Permanganate Method: For every 1000 cubic
feet add 450gm of Potassium permanganate (KMnO4) to
500 ml of formaldehyde. Take about 5 to 8 bowels with
equally divided parts of formaldehyde and add equally
divided KMnO4 to each bowel. This will cause auto
boiling and generate fume.
After the initiation of formaldehyde vapour
immediately leave the room and seal it for at
least 48 hours
Neutralise residual formalin gas with Ammonia
by exposing 250ml of Ammonia per litre of
Place the Ammonia solution in the
centre of the room and leave it for
3 hours to neutralise formalin vapour.
Operation Theatre volume=L×B×H=20×15×10=3000
Formaldehyde required for fumigation=500ml for 1000
So 1500ml Formaldehyde required
Ammonia Required for neutralisation=150ml of 10%
ammonia for 500ml of formaldehyde
So 450ml of 10% ammonia required
Phosphine is the compound with the chemical formula
It is a colorless, flammable, toxic gas. Pure phosphine is
odorless, but technical grade samples have a highly
predominant fumigants used for the fumigation of OT &
bulk-stored grain throughout the world.
phosphide or magnesium phosphide.
When exposed to heat and moisture the formulations
release phosphine, a highly toxic gas.
The time required for release of phosphine will vary with
temperature and formulation.
Phosphine is very toxic to all forms of animal life, hence
exposure of human beings even to small amounts should
Phosphine can be produced via tablets or phosphine
Phosphine is generaly used for fumigating huge
quantity of food grain than operation theatre
Phosphine producing Equipment
1,3-dichloropropene & chloropicrin
1,3-dichloropropene & chloropicrin is generaly used as soil
Methyl isocyanate is an intermediate chemical in the
production of carbamate pesticides.
Methyl isocyanate fumes can also be used as a fumigant.
Methyl isocyanate (MIC) is extremely toxic.
It was the principal toxin involved in the Bhopal disaster.
Even small quantity is extremely toxic to humans, so currently
not used in fumigation.
Methyl Bromide is most widely used fumigant for
It is a preferred fumigant because of its good
penetrating ability, rapid action, high toxicity to a broad
spectrum of micro organisms and pests.
The effectiveness of methyl bromide is based on the
Dosage of the fumigant
Duration of exposure
When fumigation is carried out with Methyl Bromide
fumigant, there will not be any residual issues as aeration
can be carried out easily.
Methyl Bromide fumigation can be carried out at the
dosage that varies between 32 grams/ m3 and 80
grams/ m3 as per the requirements.
Methyl bromide is considered to be a significant ozone
depleting substance (ODS) by atmospheric scientists.
Methyl bromide is readily photolyzed in the atmosphere
to release elemental bromine, which is far more
destructive to stratospheric ozone than chlorine.
Preparation for fumigation
First the area intended to be fumigated is usually
covered to create a sealed environment.
The fumigant is released into the space to be fumigated.
The space is held for a set period while the fumigant gas
percolates through the space and acts on and kills any
The space is neutralised & ventilated so that the
poisonous gases are allowed to escape from the space,
and render it safe for humans to enter.
Windows, doors should be closed. AC and AHU should
be switched off before starting fumigation.
Area under fumigation, do not enter status label should
be displayed on either side of the entrance.
Fumigants are irritating and toxic to human eye, nose
and throat. Therefore use of nose
mask and goggles while doing
fumigation is advisable.
Under certain conditions formaldehyde can react with
hydrochloric acid and chlorine containing disinfectants
such as hypochlorites to form chloromethyl a potential
HCl and chlorine containing disinfectants must therefore
be removed from areas before fumigation.
Check levels of residual fumigant in the room with
suitable air monitoring equipment(formaldameter or air
The procedure is best carried out overnight.
a period of not less than 12 hours the room
must be well ventilated.
is usable only when the level of formaldehyde is
less than 2ppm.
Personal care while Fumigation
care must be taken by wearing cap,
mask,foot cover, spectacles.
is irritant to eye & nose; and it has
been recognized as potential carcinogen.
leave the room after
the initiation of fumigants.
the fumigating employee must
be provided with personal
Advantages of Fumigation
Fumigants are toxic to all forms of life. Therefore, it is
possible to control all life stages of Micro organisms.
Fumigation is often the quickest way of controlling an
infestation, saving time and money.
Fumigants can reach where sprays, dusts, aerosols etc
Reduced residue problems in treated areas.
Fumigants are used where standards call for "zero
Microbial tolerance" in products or living environments.
Disadvantages of Fumigation
¤ Generally Formaldehyde is used for OT fumigation.
Based on the available evidence in OSHA’s record on
isgenotoxic, showing properties of both a cancer initiator
In humans formaldehyde exposure has been associated
with cancers of the lung, nasopharynx and nasal
Symptoms of excessive exposure include respiratory
irritation, itchy eyes, runny or stuffy nose, sore throat and
redness, burning sensation, scaling and irritation of skin.
Eye contact can cause pain, burning sensation, blurred
vision and excessive tearing.
Further, formaldehyde can cause difficulty breathing in
allergic individuals, particularly those with asthma or
another respiratory condition.
is an age old process of sterilisation, of
the environment, may be a sick room or operation
In spite of brief stay of patients in the operation
theatre, the environment of operation theatre plays a
great role in the onset and spread of infections.
But every hospital should pay good attention in proper
maintenance of air conditioning plants, ventilator
systems, and to have greater control on mechanisms
and personnel involved in disinfection.
Many believe that routine Microbiological monitoring is
most essential but in reality it is not practicable.
Special air flow pattern (the air flow pattern is such that
filtered and purified air circulates and contaminated air
is removed continuously).
There should be restriction of personnel traffic, closing of
OT doors and a good ventilation system.
chemical agents, good theatre practice, discipline, can
provide a microbiologically safe environment.
Fumigation is obsolete in many developed nations in
view of toxic nature of Formalin.
Several new safe chemicals are emerging but constrains
of economy limit the use and several hours of closure of
operation theatres can be curtailed as with Fumigation.
therefore recommended that other agents such as
hydrogen peroxide, hydrogen peroxide with silver
nitrate, peracitic acid and other chemical compounds
of formaldehyde should be used in place of the
currently prevalent practice of using formaldehyde.
These agents are dispersed with the aid of a fogger-like
device inside the theatre environment.
The contact time is about an hour and the theatre can
be used immediately after the contact time.
Emerging Compounds in use for
Sterilization of Operation theatres
A newer and effective compound in
cost/benefit ratio, good material compatibility, excellent
cleaning properties and virtually no residues. It has the
advantage of being a Formaldehyde-free disinfectant
cleaner with low use concentration.
Provides complete asepsis within 30 to 60 minutes.
Cleaning with detergent or carbolic acid not required.
Formalin fumigation not required.
Shutdown of O.T. for 24 hrs. not required.
virucidal, bactericidal, fungicidal, mycobactericidal and
It contains oxone (potassium
dodecylbenzenesulfonate, sulphamic acid; and
It is typically used for cleaning up hazardous
spills, disinfecting surfaces and soaking equipment.
Though Virkon is shown to have wide spectrum of
activity against viruses, some fungi, and bacteria, it
however is less effective against spores and fungi than
some alternative disinfectants.
Several other compounds are emerging in the Market
for safer use, may need better resources for utility and