An explosion in an apartment building exposes an indoor hemp facility

An explosion shook an apartment on the second floor of an apartment building in a community in the Dietikon district in the middle of the night on March 20, 2025. The rescue workers who responded came across an indoor hemp plant in a room of the apartment: a 50-year-old Swiss man had wanted to produce butane hash oil (BHO) in his kitchen.

This is a highly potent cannabis extract that is obtained using liquid butane gas as a solvent. The concentrate has a very high THC content. The explosion caused material damage of around 40,000 francs.

As a legally binding penalty order from the Limmattal/Albis public prosecutor’s office shows, the Swiss man had been handling butane gas bottles in the kitchen of his apartment in order to extract the BHO. According to current safety regulations, the extremely flammable aerosol must not be used in closed rooms anyway.

The man had a mishap: a butane bottle fell to the ground and was so damaged that gas escaped from the bottle. This created a “gas lake” and an explosive atmosphere.

When the accused turned on a kettle at 1:30 a.m., an electrical spark was generated. The escaping gas ignited and exploded with a bang. This resulted in major property damage. It is not stated in the penalty order whether the accused was injured. However, there were apparently other people present in the apartment whose life and limb were endangered by the explosion, as the penalty order shows.

As it turned out in the following criminal investigation, the accused had operated an indoor system in a room in his apartment from October 2024. It consisted of two grow tents with a total of 52 hemp plants and corresponding accessories.

The man had already successfully harvested twice and was approaching his third harvest at the time of the explosion. He produced around 600 grams of marijuana per harvest. He is said to have given some of it away to friends and strangers, and he consumed the rest himself by smoking weed. The 52 hemp plants and the installations were confiscated the morning after the explosion.

The public prosecutor’s office has now sentenced the man to a conditional fine of 120 daily rates of 80 francs (9,600 francs) each for negligently causing an explosion, multiple offenses against the Narcotics Act and multiple violations of the Narcotics Act. The enforcement of the fine is postponed with a probationary period of two years.

However, the 50-year-old has to pay a fine of 1,500 francs and the procedural costs of around 2,340 francs, which also includes the costs of the eviction. Several civil lawsuits – the homeowner and the building insurance company of the Canton of Zurich are listed as the injured parties in the penalty order – were referred to civil proceedings. Many installations and items were confiscated, including water fixtures, hydrometers, fertilizer, power strips, power rails and plant samples.

The penalty order was not contested and is legally binding.