The Straits Times
Aug 15, 2009
Fogging works, but for how long?
THE National Environment Agency's (NEA) environmental health department director S. Satish Appoo was right in saying that thermal fogging works ('Thermal fogging does make a difference, Aug4). This was in response to Mrs Janet Lim's letter, 'Fumigating merely transfers the problem' (July 23).
But how long does the effect of fogging last? Within a few hours, mosquitoes are usually back. The number of adult mosquitoes killed by fogging in a single compound is insignificant in terms of the entire housing estate and its neighbourhood.
Furthermore, the active chemical used in fogging is cypermethrin, which is classified as a potential carcinogen (cancer-inducing agent).
Chemical fogging does not affect immature mosquitoes or their breeding grounds. Mr Appoo rightly emphasised that fogging should be employed only in the presence of a cluster of dengue fever cases or to eliminate impending occurrence of such a situation.
However, many households routinely have contractors carry out fogging at regular time intervals, regardless of the indication. It is a futile exercise that serves only to add toxic pollutants to the environment.
If cypermethrin is as harmless as the NEA has claimed, why are the workers so heavily covered and masked while carrying out the fogging?
The NEA is fully aware that effective control of the mosquito problem lies in eliminating and, most important, preventing formation of stagnant water. It should intensify its efforts along those lines.
I believe Singapore as an island can be made essentially mosquito-free. Mosquitoes normally do not stray far from their breeding grounds.
Dr Ong Siew Chey
Blogger's remarks: NEA will use the same "logic" to justify culling birds with means that include poisons. Again, such culling is ineffective as the birds return because the food source from human littering continues.
