Opaque, white steam trailing behind loud trucks were a routine sight in many a childhood around the world. In South Korea, too, trucks would wail out siren sounds while emitting disinfectants and children would chase after the trucks through narrow alleyways, breathing in the foul-smelling gas.

Used as a pesticide against mosquitoes and larvae, as well as a general means to prevent infectious disease, these disinfectants have remained a regular part of national public health measures since the mid-1900s. But within the past decade, these trucks have become increasingly difficult to catch in the streets of South Korea.

A video posted by a South Korean user, chasing after a disinfecting truck (Source: YouTube)

Traditional smoke disinfectant is effective in its ability to rapidly disinfect large areas. And its explicitly loud, smoke-spewing nature does more than give young children something fun to do — according to the Gwangjin-gu Public Health Center in Seoul, one of its advantages is that “its visible nature leads to citizen support.”

But smoke disinfectant — made by diluting kerosene or heavy oil with insecticide and sprayed with a heater — affects an unpredictable radius. This can lead to unexpected health risks to residents in nearby housing areas, according to a 2015 Ministry report from the Ministry of Health and Welfare.

Smoke disinfectants include chemicals dangerous to the environment. For example, when oils are not completely combusted, the resulting solution contains volatile compounds such as belen, toluene and other carcinogens that can be harmful to both people and the environment.

Just last year, Busan, South Korea’s second largest city with a population of three million, announced efforts to increase environmentally friendly solutions with an investment of 500 million won, according to daily newspaper Busan Ilbo. While the traditional disinfectant is still necessary for hard-to-access areas such as sewers, the ultimate goal is to reduce the use of smoke disinfectant from 72 to 25 percent.

Citizens and governmental agencies have become more cognizant of potential dangers, calling either for a ban or changes to trucks spraying disinfectant gases. The Ministry of Health and Welfare said that it recommends, instead of excessive smoke disinfectant, spray methods or targeting larvae before they develop.

With new technologies and increased health concerns, the nostalgia-inducing images of smoke trailing behind a blaring truck are surely becoming much more of a rarity. But that doesn’t mean they’ve stopped entirely, nor will they any time soon. In 2005, daily newspaper Hanykoreh reported that of 246 public health centers across the country, 239 — practically all of them — were using smoke disinfectant.

Seven years later, Hankoyreh conducted another similar study (although this time with far fewer centers) and found that 23 out of 36 public health centers contacted across the country still planned to use smoke disinfectant.

Though the traditional oil-based smoke disinfectants are far from extinct, many of the centers in the recent study are showing efforts, such as water-based solutions, to become more environmentally friendly. And as public health centers seek out new, safer mixtures, in response to rising public awareness about the possible dangers of these trucks, health measures are shifting — from what was once an explicit, loud display of communal cleaning into a humbler national effort to do the same job but maybe in a safer way.

Cover image: Though less common now, mosquito trucks spewing disinfectant smoke have long been a common sight in South Korea. (Source: YouTube)