Figure 5.

(a) Average mass concentrations (in μg m⁻³, ambient temperature and pressure) of submicrometer particulate organic nitrates (NO_{3, org}) and particulate inorganic nitrates (NO_{3, inorg}) in different months at multiple sites. The concentrations correspond to mass concentrations of –ONO₂ functionality. Note that the y axis is different for sites with total nitrates greater than 1 μg m⁻³ (shaded). Detailed information and measurements for each site are provided in Table S5. (b) Percentage (by mass; cyan) of submicrometer particulate organic nitrate aerosols in ambient organic aerosols in different months at multiple sites. Detailed information and measurements for each site are provided in Table S5.