As Figure 2 indicates, the average aerosol light extinction coefficient (Bext – Rayleigh Scattering (10 Mm^-1)) during the 20% worst days is 23.9 Mm^-1, which is about 3.3 times of the value of 7.1 Mm^-1 during the 20% best days and 1.8 times of the value of 13.2 Mm^-1 during the middle 60% days. Sulfate is the largest contributor to aerosol light extinction during the 20% worst days, and the contribution of sulfate to aerosol light extinction is  ~ 29.9% in worst days. OMC and CM also contribute ~ 23.7% and ~ 20.1% to aerosol light extinction during the worst days.

Figure 3 suggests that the the occurrence of 20% worst days is relatively constant throughout the year (in the range of ~ 15% to 25%). The highest occurrence of the 20% worst days happened in May, December and July, in which more than ~25% of the sampling days are the 20% haziest days at Canyonlands National Park. As shown in Figure 4, sulfate and nitrate are the major aerosol contributors to haze during the Winter in December, January and February. In March and April, CM is the largest aerosol contributor to haze. OMC becomes important when Summer comes. It contributes ~30% to haze in July and August. Both OMC and sulfate are important during the fall.