Cancer can be caused by exposure to air pollution released by industrial facilities. The European Pollutant Release and Transfer Register (E-PRTR) has made it possible to study exposure to industrial pollution. This study seeks to describe the industrial emissions in the vicinity of Spanish towns and their temporal changes, and review our experience studying industrial pollution and cancer. Data on industrial pollutant sources (2007–2010) were obtained from the E-PRTR registries. Population exposure was estimated by the distance from towns to industrial facilities. We calculated the amount of carcinogens emitted into the air in the proximity (<5 km) of towns and show them in municipal maps. We summarized the most relevant results and conclusions reported by ecological E-PRTR-based on studies of cancer mortality and industrial pollution in Spain and the limitations and result interpretations of these types of studies. There are high amounts of carcinogen emissions in the proximity of towns in the southwest, east and north of the country and the total amount of emitted carcinogens is considerable (e.g. 20 Mt of arsenic, 63 Mt of chromium and 9 Mt of cadmium). Although the emissions of some carcinogens in the proximity of certain towns were reduced during the study period, emissions of benzene, dioxins+furans and polychlorinated biphenyls rose. Moreover, the average population of towns lying within a 5 km radius from emission sources of carcinogens included in the International Agency for Research on Cancer list of carcinogens was 9 million persons. On the other hand, the results of the reviewed studies suggest that those Spanish regions exposed to the pollution released by certain types of industrial facilities have around 17% cancer excess mortality when compared with those unexposed. Moreover, excess mortality is focused on digestive and respiratory tract cancers, leukemias, prostate, breast and ovarian cancers. Despite their limitations, ecological studies are a useful tool in environmental epidemiology, not only for proposing etiological hypotheses about the risk of living close to industrial pollutant sources, but also for providing data to account for situations of higher mortality in specific areas. Nevertheless, the reduction of emissions should be a goal, with special relevance given to establishing limits for known carcinogens and other toxic substances in the environs of population centers, as well as industry-specific emission limits.