Fogging alone is not enough says specialist

So much so that the general public have become accustomed to the ‘fog men’ as they are called filling the air with thick and smelly artificial smoke using machines strapped to their backs or sides.

But does fogging really keep dengue under check?

Community medicine specialist and medical lecturer Dr Helmy Hazmi warns that we should not solely depend on fogging as a method to repel mosquitoes as it is only a temporary measure.

The Kuching-based specialist said fogging only kills adult mosquitoes and not its larvae.

"Yes, it does kill the adult mosquitoes and bring down their numbers, but this is only temporary. Although the adult mosquitoes are killed, the young ones - the larvae, are protected from the insecticide laden fog, only waiting for a few more days to emerge into adult mosquitoes and replace their dead comrades," said Dr. Helmy in his article published in The Malaysian Medical Gazette.

He added stagnant clean water both indoors and outdoors are perfect places for larvae growth and as such it should be drained out.

In cases where water collection is present such as in aquariums, bath and potting plants, adding abate into the water can help kill the larvae and prevent it from reaching a complete cycle.

Other factors that may prevent fogging from killing the mosquitoes is for the simple reason that sometimes home owners are not at home to allow the fog men in.

"Since mosquitoes are also active indoors, the fog men must fog indoors too. They can't fog indoors if there is no one to let them in," he said.

But with a spate of incidents resulting in harm, injuries and even kidnapping, homeowners find it difficult to allow strangers into their homes, especially one with a mask over his face.

There have been cases of fog men being turned away because of a belief that the fog would kill pets inside the home. Allaying these fears Dr. Helmy said the pesticides used are lethal enough to kill adult mosquitoes but not your pets such as rabbits and cats or even you.

As with any machine, fogging blowers need periodic maintenance in order for it to function to its maximum capacity.

But maintenance is expensive and as such overlooked, causing the nozzles to be clogged with dirt. In the end, the fog men are only emitting thick white smoke, leaving the mosquitoes unharmed.

Another limitation is that fogging requires a special skill or technique to be carried out. Dr. Helmy said the concentration of pesticides used, nozzle width, speed, swing techniques, and wind direction are all important in killing more mosquitoes.

He said much as fogging is effective as a way to prevent a possible dengue outbreak, the community plays an important role, too.