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52 diate values and those non-mechanic garage workers the lowest values. The difference between the mechanic and non-mechanic garage workers is significant at the P<0.001 (two-sided) level. (See section on possible health effects of non-mechanic garage employment.) The same difference was seen in auto body repair workers, but, because of the smaller number of individuals, it did not achieve significance at the 0.05 level (P=0.12). Possible effects from non-mechanic garage employment For the principal three spirometric tests, as well as for MMF/ PMMF, individuals with garage employment, but who did not engage in brake maintenance work, had significantly lower means and a greater percent age of abnormal pulmonary function results than either controls, brake workers, or those with possible exposure to asbestos otherwise. We investigated whether this may be the result of the greater percentage of blacks and Hispanics employed in this category compared to other job activities, coupled with improper pulmonary function standards for these groups. Table 31 shows the percentage of individuals in the various job categories according to their race. As can be seen, among those with garage employment, but no brake work, more than 40% were black or Hispanic compared to 28% of those with no identified asbestos exposure and 16% of those who worked in brake maintenance and repair. To the extent possible, we took into account the known differences between black and white populations in the predicted standards for forced vital capacity and forced expiratory volume in one second (black normals were 89% of those of whites). For MMF the same prediction parameters were used for blacks and whites as there appears little racial difference in flow rates (Schoenberg et al. , 1978). However, /- data on these standards are relatively limited and they may not be fully accurate. For Hispanics we used the same criteria as for whites. Table 32 shows the overall spirometric data according to race. As can be seen, the means for FVC/PFVC and FEV^/PFEV.^ for the black population are generally lower than the white population in all smoking categories. [The smoking standardized difference is significant at the P<0.01 level (two-sided) for FVC/PFVC.] On the other hand, the data for the Hispanic