Ground level concentrations of smoke and sulphur dioxide in Dublin approach, and on occasion exceed, values at which the World Health Organisation suggest adverse health effects may be discerned. To examine the alleged threshold position of the city in this respect hospital admission data for three winter periods from 1975 to 1978 are examined in conjunction with climatic and air pollution data for the corresponding period. Significant associations arc found between sulphur dioxide levels and respiratory and cardiovascular morbidity for the first winter studied, and between smoke levels and respiratory categories for the remaining two. Inferential deduction following multivariate analysis suggests unfavourable dispersion conditions were influential during the second winter and significant changes in the emission environment were involved during the third winter period. It is suggested that the initial effects of changing consumer fuel preference from oil to solid fuel are apparent in the relative decline of SO2, compared with smoke, as the key pollution variable with respect to morbidity and that an end to the relative neglect of this pollution parameter would now be appropriate.