Spanish police have detained 68 individuals after investigating 30 companies for emitting polluting substances.

Officers from the national police (Guardia Civil), supported by Europol, targeted the firms after suspecting them of releasing around 76 million kilos of carbon dioxide (CO2) in the atmosphere.

To put that into perspective, Europol said that a car would have to travel 800 million km to release the same amount of gases.

The operation, coordinated by the Spanish Central Prosecutor's Office (Environmental Crime), monitored authorized centers managing end-of-life vehicles (ELVs) in Madrid, Catalonia and the Basque Country.

The investigation focused on how toxic substances in air conditioning systems such as refrigerant fluids that harm the ozone layer were being disposed of illegally.

The EU has issued specific directives on how to dismantle and recycle ELVs in an eco-friendly way.

It states that owners should bring their vehicles to authorized centers and expect to receive paperwork confirming that due process was followed.

End-of-life vehicles contain significant amounts of hazardous materials that might make their way into the atmosphere, soil and water.

According to the EU, ELVs generate between seven and eight million tonnes of waste every year.

Regulators have been urging automakers to stop using harmful substances while manufacturing new vehicles, particularly lead, mercury, cadmium and hexavalent chromium.