Disinfection With Formaldehyde Fumigation

One way of disinfection is fumigation with formaldehyde gas. This can be done by heating paraformaldehyde, boiling formalin solution but the most practical method is by mixing Formalin solution, usually commercially available as 37% solution, into Potassium permanganate crystals to release the formaldehyde as gas fumes.

Formaldehyde fumigation is commonly used in fumigation boxes or chambers, an important fixture of a livestock farm biosecurity program. Located strategically at the interphase of the dirty and clean areas of the farm and with doors at both sides, equipments, supplies and materials brought into the farm can be disinfected in the fumigation chamber. Two (2) milliliter (mL) of 37% Formalin solution and 1 gram (g) Potassium permanganate crystals is required to disinfect one (1) cubic foot of air space. The computed amount of Potassium permanganate crystals is placed in earthenware bowls on the lowest level of the fumigation chamber. After closing the doors, the computed volume of Formalin solution is poured into the bowl (Very Important - Do not reverse the procedure by "pouring" the Potassium permanganate into the bowl filled with Formalin solution). The chemical reaction will release the formaldehyde gas fumes and disinfect the materials in the fumigation chamber.

Formaldehyde disinfection can also be used for livestock buildings. It is necessary that buildings to be disinfected are sealed air-tight using tarpaulin or canvass curtains to enable adequate fumigation. The computed amount of Potassium permanganate can be divided into several bowls spaced equally along the building lenght, from the end to the door. With the computed volume of Formalin solution also divided according to the number of bowls, the fumigation is started at the building end towards the building door which is then closed to fumigate-disinfect the building.

Formaldehyde fumigation is an economical and effective disinfection procedure. It should not however be a a substitute for thorough cleaning especially the complete removal of organic waste materials. As forlmaldehyde gas is toxic, irritant to conjunctiva and mucosa as well as carcinogenic, extreme precautions must be observed like wearing protective clothing, hand gloves, gas mask and eyewear, to protect individuals performing the fumigation. The chemical reaction of formalin and potassium permanganate produces a lot of heat and glass, plastic and metal bowls are not suitable to use.