Steel mill licks toxins undetected for months

This winter a dioxin leak appeared in the Gerlafingen Steelworks. How did it happen?

This winter a dioxin leak appeared in the Gerlafingen Steelworks. It was unnoticed for months. The cause: a defective activated KOKS injection system. Pollutants such as dioxins, furans and heavy metals could not be filtered out. Instead, they were released into the environment.

Patrick Puddu, a member of the management team at Stahl Gerlafingen, admitted to the newspaper Tages-Anzeiger that this was a serious mistake, as the company held up for sustainability.

The Steelworks explains this with a change to a new surveillance system that “had given the defect unsatisfactorily”. As a result, “the malfunction was not noticed in the winter months”.

The company sees the cause of the leak, which has long been undiscovered, in the switch to a new surveillance system that does not sufficiently indicate the malfunction. The problem was only identified and resolved when the purchasing department found that no active cola was activated.

The residents do not have to fear their health

A routine measurement of the chimney, which the environmental authority ordered every three years, also contributed to the discovery. This measurement took place on February 19, 2025, but the results were only available two months later. On April 15, Stahl Gerlafingen informed the canton about the leak.

In consultation with the authorities, the Steelworks now checks the functionality of the system daily.

Due to the incident, the residents do not have to be afraid for their health, an expert from the Tages-Anzeiger newspaper said. The toxic substances would dilute relatively quickly. In the soil around the steelworks, however, increased dioxin levels can be measured in the soil, which can be attributed to the significantly higher emissions in the nineties. The dioxins bind to dust particles in the air and land with them in the ground.