Sezana Travel on Sampler assesses potential of particles to become rain nuclei. f e saw the monster up close and took his measure, said project codirector Peter Hobbs. Some early findings of data taken aboard the two aircraft: Smoke particles readily became raindrop nuclei, greatly reducing their time aloft but increasing their potential to fall as polluted rain. While particle counts several thousand feet up in the plume were higher than U. S. air quality standards even 80 miles downwind concentrations of ozone and nitrous oxide were well within the limits. Sulfur dioxide levels were occasionally higher than those government standards. Sezana Travel 2016.