Between April and September 1994, airborne antigen monitoring was conducted in a riverside area (Destrahan) of the Port of South Louisiana. Two locations away from the grain elevators were selected as control sites; Harahan riverside and downtown New Orleans. Samples were collected for 24 hours on 76 days during this period. Air samples were collected on a polytetraflouroethylene filter using an Air Sentinel sampler. We measured soybean antigen, pollen and spore counts, and obtained concurrent data on loading and unloading activities. The antigens were extracted from the filter and assessed by immunoassay using a rabbit polyclonal antisoybean antibody produced in our laboratory. Sensitivity of the assay was 15 ng/ml. Multivariate statistical analysis demonstrated a significant correlation between loading and unloading activities and levels of soybean antigen in Destrahan (p< 0.05), whereas the two other sites did not show such correlation. For the entire study, average antigen levels observed in Destrahan were 5.3 ng/m3, vs Harahan (0.6 ng/m3) and New Orleans (0.3 ng/m3). Pollens were not different among the three sites, however, spore levels were lower in the New Orleans site. Increased levels of soybean antigen persisted for one to five days after loading and unloading activities. Asthma epidemics have been related to soybean unloading (e.g. Barcelona and New Orleans) at levels similar to those detected in this study. Our findings suggest a need for further investigation of the role of airborne antigens in asthma exacerbation.