Student Research: Shannon K. Heath
The objectives of this study were to compare the change in pulmonary mechanics and nasal function upon exposure to low levels of sulfur dioxide (SO2) between a group of African-American asthmatic males and a group of Caucasian asthmatic males, of similar income and education level. All subjects performed an exercise tolerance test and methacholine challenge test to determine their asthamtic status. Ten African-American and twelve Caucasian asthmatic males were exposed to pure air or 1 ppm SO2. while breathing inside a polycarbonate head dome, for 20 minutes: the first ten minutes were at rest and the second were during moderate exercise. The pulmonary function measurements assessed were forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), total respiratory resistance (RT) and maximal flow at 50 and 75% (Vmax50 and Vmax75) of expired VC, recorded while the subject was sitting in a plethysomograph. Baseline and post exposure nasal lavage fluid were collected and processed. Epithelial cell counts and white blood counts were made. Results of this study showed no significant differences in pulmonary or nasal measurements after exposure to sulfur dioxide between the African-American and Caucasian subjects. There was a statistically significant increase in RT upon exposure to SO2 as compared to the changes observed with air exposure when the data from both groups' pulmonary function data were analyzed (p < 0.05). No significant changes in epithelial or white blood cell count were found when data were analyzed from the entire group or either of the two subject groups. Among this study group, no measurable differences in effect of SO2 were found between members of the African-American and Caucasian ethnic groups, of the same socioeconomic class. However, because of the wide variability in pulmonary and inflammatory response to SO2 between subjects within each ethnic group, the group results masked the fact that some individuals were particularly responsive to SO2. The recommendation is made that all individuals placed in occupational settings where they may be exposed to even low levels of SO2 are given pulmonary function tests prior to employment. Tests should be repeated at regular intervals after exposure to improve the recognition of those individuals most susceptible to this pollutant and prevent further pulmonary function decrements through job modification.