Transboundary Pollution Crisis Due to Chemical Warehouse Fire in Guadelajara, Spain

On May 14, 2025, a fire broke out in a warehouse storing hazardous chemicals such as organic solvents and strong oxidizers in the city of Guadelajara in southern Spain, which quickly got out of control due to the violent reaction of the chemicals. On-site monitoring showed that the blue-green smoke released by the combustion contained high concentrations of sulphides, nitrogen oxides and dioxin-like substances, the formation of which led to PM2.5 particles spreading through the atmosphere into the sea off the Strait of Gibraltar. Worse still, some 30 tons of incompletely burned chemicals flowed into the Guadalquivir River along with firefighting wastewater, causing dissolved oxygen levels in the estuary to plummet to 2.1mg/L (compared to the normal ≥5mg/L) and near extinction of the plankton community. The Spanish Marine Institute warns that if the pollutants enter the Atlantic Ocean with the tides, they could affect the fishery resources in the Gulf of Cadiz, where tuna catches account for 37% of Spain’s total production. The European Union has initiated an emergency procedure under the Water Framework Directive to coordinate joint monitoring of pollutant dispersion pathways in neighboring countries such as Portugal and Morocco.