GSTM1 and diabetes mellitus: We calculated the corresponding air EO exposure levels based on the equation, i.e., the overall population mean HbEO was 31.56 pmol/g Hb, equivalent to 2.90 ppb air exposure; the log2-HbEO inflection point for prediabetes was 7.52 pmol/g Hb, equivalent to 16.84 ppb; and for diabetes was 8.03 pmol/g Hb, equivalent to 23.98 ppb.