India accounted for about 82% of all malaria cases in South-East Asia in 2020. Reported cases of dengue in India increased by 22% from 2019 to 2021. Both malaria and dengue are mosquito-borne diseases. With this alarming context in mind, Valencia Fernandes, Sub Editor, Clean India Journal peers into the smoky world of fogging, which has been India’s mainstay for mosquito control.
What is fogging?
Fogging is a technique for killing airborne pests by spraying fine pesticide particles into the air with a machine or blower. In some cases, water or diesel is used as a carrier to spray pesticides into the atmosphere. When diesel is used, a thick fog is produced that is visible, whereas when water is used, the fog is not visible due to its ultra-fine nature.
Because diesel emits smoke, it serves as a good carrier for the finest particles to enter the atmosphere. This process allows the pesticide to remain in the air for a longer period. The modus operandi of fogging is that the mist dispersed into the atmosphere covers every available surface.
Mosquito fogging is intended to kill any adult mosquito. After biting a patient suffering from malaria, dengue or other mosquito-borne illnesses, the mosquito becomes a carrier of the virus or parasite, and can infect other humans through its bite. Hence, it is critical to keep mosquito infestation under control.
What is fumigation?
Fumigation is a method of killing insects or pests in confined spaces. Pests are killed by suffocation or breathing in the chemical from the air.
First, the entire house or area must be thoroughly sealed. Only then should the chemical that is toxic to pests be released into the premises’ atmosphere. This is injected into the nooks and crannies of the fumigated area, where it kills all pests in the vicinity. The area is then degassed, and the premises is re-ventilated, allowing humans to return inside. This is an important stage in the process because it reduces the possibility of choking or developing any side effects.
Rachit Aggarwal, Director, Truly Nolan said: “In India today, fumigation is only used in agriculture, greenhouse storage or warehouses. Fumigation of grains occurs to prevent infestation or food destruction. This is solely for the sake of food security. It is proper to apply this technique only in this sector. Fumigation is extremely toxic and should not be used in households.”
“In hospitals”, he continued, “We are asked to fumigate OTs, which is hazardous. We try to educate them about the difference between fumigation and fogging and suggest the Ultra-Low Volume form of fogging to ensure the environment is pathogen-free”.
Types of Fogging
Thermal fogging is a process in which the fogging machine emits smoke into the atmosphere when the machine’s coil is heated. The pesticide is dispersed into the air using diesel, which is a good pesticide carrier.
Ultra-low volume ULV or Cold fogging is a type of fogging in which fine particles of mist are released into the air using water. These particles settle on the ground and other surfaces such as plants and trees for a longer period. When mosquitoes or flying insects land on these surfaces, they suck in the chemical, causing the insect to choke and die. In most cases, hydrogen peroxide is used in the fogging process.
Where is cold fogging applicable?
Cold fogging can be done both outside and inside. Thermal fogging is not permitted indoors as it is a fire hazard. Because it uses water, cold fogging can be used anywhere, but its effectiveness is dependent on the pests or microbes being targeted. As a result of its dual application, cold fogging is preferable to thermal fogging.
Is fogging effective?
According to Aggarwal, “Mosquitoes do not develop resistance to fogging; rather, they develop resistance to the chemicals used. We have been using the same chemicals and the same active ingredients for the last 30-40 years, which is why mosquitoes are slowly developing resistance.”
Half measures not enough
We have grown accustomed to seeing public officials smoke out or fog our neighbourhoods. This regular occurrence is something we all take for granted. The thick smog that engulfs the atmosphere is a temporary drill that disappears in a matter of minutes. Giridhar Pai, Director, PECOPP Pest Control Services Pvt Ltd. warned: “By only fogging, you will not be able to completely control the mosquito problem or the spread of mosquito diseases. Controlling either egg laying or adult mosquito production will help to alleviate the problem”.
Because the Indian climate encourages mosquito breeding, stronger measures are needed to limit and prevent their spread. Stagnant water drainage, water body monitoring and proper rainwater storage should be prioritised.