Fumigation: Definition, Requirements, Preparation, Procedure and applications
Definition of fumigation
Fumigation is a process where fumigant, a chemical at required temperature and pressure can exist in a gaseous form in sufficient concentration will be lethal to pest organisms. It is very useful method to control insect pests, disease and nematodes. But in reference to medical field, it uses for reduction of microbial agents ( bacteria, fungi, virus) on hospital surfaces and to control surgical site infections as well as for areas where microbiological cleanliness is required.
Requirements for fumigation
Personal Protective Equipment (PPE) set that includes face protection, goggles and mask or face shield, gloves, gown or coverall, head cover, and rubber boots.
Formalin/ saturated formaldehyde solution (37%)
Distilled water (D/W)
Choosing formaldehyde as a fumigant for hospital set up
Formaldehyde fumigation has long been an accepted method for areas where microbiological cleanliness is required because of following properties-
Low temperature heating produces vapor.
Vapor phase decontaminates the air i.e. environment.
It kills vegetative bacteria / spores.
When formalin mixed with water and exposed to elevated temperature
Gaseous formalin is generated.
To sterilize the operation theater,ICU/NICU rooms or areas where microbiological cleanliness is required.
Formaldehyde gas (bactericidal, sporicidal, viricidal) is widely employed as it is cheaper for sterilization of huge areas like operation theaters.
Formalin kills the microbes by alkylating the amino acids and sulfydral group of
proteins and purine bases. In spite of the gas being hazardous continues to
be used in several developing countries.
Preparation prior Fumigation
Fumigation usually involves the following phases-
First the area to be fumigated is usually covered to create a sealed environment next the fumigant is released into the space to be fumigated.
Then the space is held for a set period while the fumigant gas percolates through the space and acts on and kills any infestation in the product.
Next the space is ventilated so that the poisonous gases are allowed to escape from the space, and render it safe for humans to enter.
Thoroughly clean windows, doors, floor, walls and all washable equipment with soap and water.
Close windows and ventilators tightly. If any openings found seal it with cellophane tape or other material.
Switch off all lights, A/C and other electrical electronic items
Calculate the room size in cubic feet (Length X Breadth X Height) and
calculate the required amount of formaldehyde as given in.
Personal care during fumigation: Adequate care must be taken during wearing PPE that includes face protection, goggles and mask or face shield, gloves, gown or coverall, head cover, and rubber boots. (Note- Formaldehyde is irritant to eye nose and it has been recognized as a potential carcinogen. So the fumigating employee must be provided with the personal protective equipment.)
Creating the Formaldehyde gas:-Electric boiler fumigation method for each 1000 cubic feet of the volume of the operation theater-500 ml of formaldehyde (saturated i.e. 37% ) added in 1000 ml of water in an electric boiler. Switch on the boiler, leave the room and seal the door. After 45 minutes (variable depending to volume present in the boils apparatus) switch off the boiler without entering in to the room .
Another Method of Fumigation
In principle we have to generate formaldehyde gas. It can be performed by most easier way to mix the needed quantity of formalin to water and heating at lower temperatures at 80°C to 90°C. It can also be done with addition of formalin to potassium permanganate. Adding potassium permanganate to formaldehyde. This method is for every 1000 cubic feet, add 450 gm of potassium permanganate (KMnO4) to 500 ml of formaldehyde (37%). Take about 5 to 8 bowels (heat resistant place it in various locations) 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 vapor, immediately leave the room and seal it for at least 48 hours.
Neutralization of Fumigation
Neutralize residual formalin gas with ammonia by exposing 250 ml of ammonia per liter of formaldehyde used. Place the ammonia solution in the center of the room and leave it for 3 hours to neutralize the formalin vapor. e.g. Operation theater volume ( length 30 ft., breadth 20 ft. and height 10 ft.) 6000 cubic feet and then formaldehyde required for fumigation 500 ml for 1000 cubic feet So, 3000 ml of formaldehyde required. Ammonia is required for neutralization 150 ml of 10% ammonia for 500 ml of formaldehyde So, 900 ml of 10% ammonia required.
Alternative chemical agents needed in hospital use having following properties-
A need for aldehyde free based chemicals is growing concern. e.g. brand name ‘Hospal-Aero’ -Aldehyde free Aerosol Disinfectant for fogging
Need for quicker sterilization methods with ever increasing work loads.