At today's Lunch 'n' Learn, Andy Ballantine told about two dozen people more about dust than most imagined possible. Atmospheric dust can affect the world in powerful or subtle ways, though its effect here in Maine is not thought to be great.

Andy told us that 1 to 3 billion tons of dust move about in the atmosphere each year. Each particle of dust can carry several hitchhiking microbes, which adds up to 1 quintillion (a 1 and 18 zeros) microbial bits up there (enough to stretch from Earth to Jupiter). Ten percent of those microbes are human pathogens.

While some Saharan storms kick up dust that crosses the Atlantic toward South America and some of that dust works its way north toward the eastern United States (following the path that hurricanes take), not much of it reaches as far as Maine. And ultraviolet rays likely kill off most plant pathogen microbes en route.

Selected readings on atmospheric dust

• USGS Global Desert Dust Program
• Dust Storm Conditions in Africa
• Atmospheric Dust and Climate Change