NEW YORK (CBSNewYork) — For the first time, scientists have quantified the number of viruses circling the planet.

“Every day, more than 800 million viruses are deposited per square meter. That’s 25 viruses for each person in Canada,” said University of British Columbia virologist Curtis Suttle, one of the senior authors of a paper in the International Society for Microbial Ecology journal.

That number accounts for viruses above Earth’s weather systems but below where air planes fly, according to

The viruses are swept up in small particles from soil-dust and sea spray, and according to Suttle, it is quite possible that they are transported across continents.

Most of the bacteria and viruses come back down in rain, and even more by Saharan dust storms blowing over North Africa, the Mediterranean and Southern Europe.