Damage such as roadside trees dying and soil contamination is recurring due to de-icers spread across streets in winter. The government is promoting ‘eco-friendly de-icers’ as an alternative, but the actual environmental improvement is minimal, prompting calls for structural measures that overhaul snow-removal practices.

According to Seoul’s de-icer usage on the 26th, last winter (November 2024March 2025) the city used 73,258 tons of de-icers, about 20% more than the previous winter (60,819 tons). Compared with the winter of 2019 (10,462 tons), this is about a sevenfold increase.

Although total annual snowfall is trending downward due to climate change, de-icer use is increasing as authorities strengthen preemptive responses to road-icing risks and safety complaints.

The de-icers most local governments use are calcium chloride and sodium chloridechlorine-based chemical de-icers. About 80% (58,232 tons) of the de-icers used by Seoul last winter were calcium chloride and sodium chloride. Eco-friendly de-icers without chlorine components accounted for 20% (15,026 tons) of the total.

When chlorine-based de-icers are applied in large quantities, they cause serious environmental side effects. They acidify soil, hinder the growth of street trees, and in severe cases can kill them. If chlorides flow into rivers or lakes, they may lead to water pollution. They also damage infrastructure by harming road surfaces and corroding bridges, and de-icers dispersed on streets can trigger respiratory illnesses, adversely affecting human health.

To reduce side effects from de-icer use, the government recommends using eco-friendly de-icers. The Ministry of the Interior and Safety has issued guidelines calling for at least 20% of total de-icer usage to be eco-friendly products. Since 2013, the Public Procurement Service has supplied only de-icers certified with the environmental label.

However, the ‘eco-friendly’ benefits of these products are not as great as expected. According to a study by a Seoul National University research team published last year in the international environmental science journal (Science of the Total Environment) titled ‘Effects of eco-friendly de-icers on street trees’, eco-friendly de-icers also caused damage to street trees comparable to sodium chloride when exposure was prolonged.

Lee Deok-hwan, emeritus professor at Sogang University (chemistry and communication), said, “Most ‘eco-friendly’ de-icers on the market do not deliver ‘eco-friendly’ effects,” adding, “Rather than increasing de-icers that are eco-friendly in name only, we need tailored snow-removal measures that take into account local road conditions and environments.”