Fig. 5: Mass concentrations and fractional contributions of 14 ON source factors during the measurement period.

a Box plots showing the distributions of ON mass concentrations for the 14 source factors. Square markers and horizontal lines in the boxes indicate the mean and median values, respectively; boxes represent the 25th and 75th percentiles, and whiskers represent 10th and 90th percentiles. b Percentage contributions of individual source factors to ON in PM2.5. c ON mass concentrations and corresponding fractional contributions of the 14 source factors to the total aerosol ON.