Sewer odors present a major problem for municipalities. This is generally the only time the public and the hidden infrastructure of sewer systems interact, and it is of course a negative interaction. The analysis of sewer odors comprises two components – airflow and concentration. This presentation concerns the first component – airflow rates. Hydraulic output from SWMM was used to compute the airflow rate in a sewer system based on an extensive set of field measurements. The SWMM ventilation model was then validated using field data obtained from sewer systems throughout the world. The results were encouraging and showed the SWMM results were generally close to the actual field data. The field data spanned a large range of measured airflow rates from 10 – 10,000 m3/hr.