Ultrafine particle and fine trace metal (As, Cd, Cu, Pb and Zn) pollution episodes induced by industrial emissions in Huelva, SW Spain

► We studied how industrial emissions contribute to ultrafine particles (UP). ► Traffic and industrial UP episodes are identified from the relation of UP and PM2.5. ► Road traffic emissions, in the morning rush hours, are associated with OM and BC. ► Industrial plumes, during daylight, are related with heavy metals. ► Industrial emissions are the first cause of high UP in Huelva city.