BACKGROUND: The objective of this study was to estimate the relationship between the levels of air pollution and the daily mortality in the city of Huelva for the 1993-1996 period using the EMECAM methodology. METHODS: The number of daily deaths for all causes except external ones, the death rate of those over age 69, due to diseases of the circulatory system and for respiratory diseases were used as rate indicators. Four pollutants--SO2, PM10, NO2 and CO--were analyzed, the daily levels of which were furnished by the air pollution monitoring network in Huelva. Autoregressive Poisson regression models were constructed controlling by tendency, seasonality, temperature, humidity, flue and events out of the ordinary. RESULTS: For the mortality rate for all causes, a significant association impact was found to exist for the NO2 for the entire period (RR10 microgram/m3: 1.0414; CI95%: 1.0047-1.0794) and for the particles (PM10) for the cold half of the year (RR10 microgram/m3: 1.0358; CI95%: 1.007-1.0722). For the mortality in people over age 69, a significant relationship was found to exist for SO2 throughout the entire period (RR10 microgram/m3: 1.0606; CI95%: 1.0020-1.1227). A significant relationship to the mortality from respiratory disease particles (PM10) was found to exist for the cold half of the year (RR10 microgram/m3: 1.1412; IC95%: 1.0300-1.2644). There was no association of contaminants with cardiovascular mortality; also there was no association between levels of CO and mortality indicators. CONCLUSIONS: In Huelva, significant relationships have been found to exist between the current levels of air pollution resulting from particles, SO2 and NO2 and the daily mortality. The impact of these pollutants on the mortality is coherent with scientific literature, although in the case of Huelva, the extremely small number of daily deaths due to its small population and other factors limit the consistency thereof.