The Mosquito Truck

Dear Korean,

What chemicals are used in the mosquito fogging trucks and are they harmful to people? If so, why are they so accepted by Korean society?

James M.

If you don't know what James M. is talking about, this is the mosquito fogging truck that can be seen in Korea from time to time:

The fog is mostly made up of kerosene, mixed in with a small amount of pesticide. (The ratio is around 300:1 kerosene to pesticide.) The petroleum-based "carrier" is heated into a fog, which carries the pesticide particles that would eventually kill mosquitoes.

Why do this? This is a great example of how little distance there is between the poorer-than-sub-Saharan-Africa Korea of the 1960s and the modern-wealthy-and-technologically-advanced Korea of the 2010s. In the bad old days of Korea, mosquitoes were one of the greatest threats to public health. As recently as 1982, Japanese Encephalitis -- only one of the many diseases carried by mosquitoes -- infected nearly 1200 people every year, killing more than 50 of them. And the most efficient way to kill the mosquitoes was the fog truck, spraying pesticide in a large area. (This practice actually was instituted by the U.S. military, as they occupied South Korea at the end of World War II.) Although mosquito-borne diseases are less of a threat today, anyone who spent a summer in Korea can tell you that the incessant mosquito attacks are quite a nuisance.

Obviously, the fog is harmful to people -- pesticide is meant to kill living things. But the amount of pesticide involved is actually very small. For an hour's worth of spraying, less than 30 ml of pesticide (= 1.5 tablespoon) is used. The bigger problem of the fog, in fact, is the kerosene, which is carcinogenic and causes air pollution. Because of the health and environmental concerns, many of Korea's municipalities have banned the use of the fog truck, opting instead for water- or vegetable oil-based sprays.

But then again, the poor country habits die hard. Kerosene-based pesticide fogging is cheaper, and it is a nice demonstration that the local government is doing something -- it just seems so effective. So a lot of smaller cities continue to use the truck, and it is not uncommon for a group of residents in a city to hire a pest control company to fog the neighborhood.

(N.B. One of the Korean's fondest memories of his childhood is Korea was to run after the fogging trucks. When you were a kid growing up in Korea, it was a thing to do -- the "fart truck" came through the neighborhood, you chase it while screaming at the top of your lung. It was a lot of fun. Generations of Koreans grew up chasing the fog truck, and we all turned out fine.)

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