Microbiology Difference Between Fumigation and Fogging and Validation of Fogging in Cleanroom
Fumigation and fogging are two methods commonly used in pharmaceutical companies to control the microbial contamination in controlled area. But now a day’s fumigation of formaldehyde solution (HCHO) and potassium permanganate is banned by different regulatory agencies.
Fumigation and Fogging:
Fumigation: Fumigation is a method in which we use formaldehyde solution with potassium permanganate chemical in a predefined ratio. Formaldehyde is a strong disinfectant. By adding potassium permanganate in formaldehyde a reaction take place and generate fumes. Generated fumes kill bacteria, fungus and their spores.
This is very effective method to control the microbial contamination in cleanroom.
Different regulatory agencies banned fumigation with formaldehyde and potassium permanganate after having so much effectiveness. The reason is that formaldehyde is carcinogenic (cancer causing) in nature and there is a risk of cancer associated with this to the personal who is handling formaldehyde. There are also other drawbacks like fumigation with formaldehyde cause irritation to the eyes and nose. After fumigation there is requirement to de-fumigation of the area in which air-handling unit (AHU) has to be continuously run for few hours without any activity to remove the residues from the air and cleaning and moping of equipment’s and area is also required.
Why Hydrogen peroxide?
In case of Hydrogen peroxide and silver ion solution, it is safe for the personal and no-residue left after fogging as it decompose in the water and nascent oxygen. There is no requirement of defogging and cleaning of equipment’s and no need to remove the residue of the solution.
Fogging: Now a days fogging is used in pharmaceuticals to control the microbial contamination in controlled area. Fogging done with the help of fogger machine and a fogging solution.
Different disinfectants are also used for fogging as claim by the vendor which can effectively control the area.
Now, in Most of pharmaceutical industries commonly uses hydrogen peroxide and silver ion solution.
(ULV) Ultra low volume foggers are generally used for fogging. By these fogger machine solution is sprayed in the area in form of aerosol. The small particles of disinfectant solution suspended in air for long time and kill all the airborne bacteria, fungus and their spores. This is also very effective method to control the microbial contamination in controlled area.
Why need fogging?
Fogging is done to sterilize the air of controlled areas. Generally fogging is not required when AHU runs continuously but when the microbial load increase in the controlled area it is controlled by fogging the area. Mainly sterile manufacturing and microbial testing area need to fogging.
Validation of Fogging Process:
Fogging process should be validated for its efficiency of removing the microbes from air. It is validate with the bacterial spore strips.
Validation of fogging is also required to verify the effectiveness of the fogging. There are some indicators for the validation of fogging efficiency in controlled areas. It can be validated with the help of strip of Geobacillius stearothermophillus ATCC 7953. These strips are manufactured by TERRAGENE SA (Argentina) with the product name BIONOVA. These are perforated stainless steel coupons having spores.
BIONOVA spore coupons biological indicators are placed at the different locations in the controlled areas especially at the critical locations as the corners and behind the equipments. After fogging the room these strips are collected and incubated in the MC20 growth medium provided with biological indicators at 60±2°C for 24 hours.
The color of MC20 growth medium should not be changed to yellow after incubation at 60±2°C. Change in color of growth medium indicates the presence of living microbes in the strips and shows the unsuccessful of the process. While no change in color of growth medium shows the effective fogging of area.