Foggy impact of fumigation on dengue, chikungunya

October 02, 2016 12:00 am | Updated November 09, 2021 01:51 am IST - NEW DELHI:

The govt and the civic bodies have taken up fogging on a war footing, but experts are divided on its effectiveness in checking the mosquito problem

As the number of deaths from dengue and chikungunya spiked in September, the Delhi government and the municipal corporations responded in the way they do every year when cases of vector-borne diseases shoot up in the monsoon: they ramped up fogging, or fumigation, across the city.

Plumes of diesel and malathion, an insecticide that has low toxicity for humans but can be more dangerous if ingested, soon rose up from the roads and alleys.

On September 14, Aam Aadmi Party (AAP) Minister Kapil Mishra and BJP MP for north-east Delhi Manoj Tiwari were photographed on bicycles fitted with fumigation devices, spraying insecticide into the air in Sonia Vihar.

Full effort

The government and civic bodies pledged more resources to their respective efforts. Deputy Chief Minister Manish Sisodia said 600 more machines would be deployed. The cash-strapped East Delhi Municipal Corporation recently procured 30 new hand-held devices, adding to the 182 it already possessed.

In total, the EDMC, the North Delhi Municipal Corporation and the South Delhi Municipal Corporation have 1,100 hand-held fumigation devices. The three corporations also have 25 vehicle-mounted fogging machines.

‘Minimal impact...’

There’s only one problem.

Experts, municipal officials and councillors are divided on whether fogging is really helping Delhi deal with the mosquito menace.

Councillors and municipal officials have repeatedly said in meetings of Standing Committees that fumigation has minimal impact on controlling the spread of vector-borne diseases as it only targets adult mosquitoes, not the larvae.

‘...but people are satisfied’

But, it works well in one way.

“People are satisfied. I can’t comment on the scientific impact, but the fumigation drive is working,” said Subhash Arya, the Leader of the House in the SDMC.

The SDMC has borne the brunt of the mosquito menace, with 353 of the total 1,692 dengue cases as of September 24 coming from South Delhi — the highest of the three corporations.

Mr. Arya added that while adult mosquitoes are killed through fumigation, the practice can’t lead to total eradication of the disease-carrying insects. However, he said the fogging efforts had been intensified.

Not all residents are satisfied though.

B.S. Vohra, the president of the east Delhi RWAs Joint Front, said that while regular fogging is being carried out, the results are short-lived.

“There is respite from mosquitoes for a few hours or a day at most after fogging, but then the mosquitoes are back. In almost every other household there is a patient of chikungunya or dengue,” said Mr. Vohra.

Apart from questions about its effectiveness, there are concerns about the environmental and health impact. As per the National Vector-Borne Disease Control Programme’s Operational Guidelines for Urban Vector-Borne Disease Control 2016, one part of malathion is to be mixed with 19 parts of diesel.

Last year, when Delhi saw a record-breaking number of dengue cases at over 15,000, the Centre for Science and Environment (CSE) had said that the fogging drive was ineffective in controlling the disease.

Adding to that, the director-general of the CSE, Sunita Narain, told The Hindu on Saturday that fogging was the “last resort” all over the world.

“It is being seen as ineffective. Over time, it builds resistance and even impacts water sources. What is being done for site management where breeding occurs? Every pothole, every garbage dump is a potential site for breeding,” said Ms. Narain.

Fogging has little impact on controlling the spread of diseases as it only targets adult mosquitoes

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