Seventh-day Adventist (SDA) non-smokers who had resided since 1966 within five miles of their 1977 residence (n = 3914) completed a standardized respiratory symptoms questionnaire in 1977 and again in 1987. For each participant, cumulative ambient concentrations from 1977 to 1987 of suspended sulfates (SO4) in excess of several cutoffs as well as mean concentrations were estimated by interpolating monthly ambient concentration statistics from state air monitoring stations to the individual's residential and workplace zip codes. There were significant associations between ambient concentrations of suspended sulfates and development of new cases of asthma, but not new cases of overall airway obstructive disease (AOD) or chronic bronchitis. Comparison of previous analyses, in this population, of respiratory disease symptoms and total suspended particulates (TSP), ozone, and sulfur dioxide (SO2), and multipollutant analyses of these pollutants with SO4, indicated these results were not due to a surrogate relationship with other air pollutants. Development of definite symptoms of AOD and chronic bronchitis was most strongly related to TSP.