There are several practical applications for this research. For example, it could lead to a nationwide bacteria census, which would show the normal levels and yearly fluctuations in the amounts of certain pathogens in the air. This could help the Department of Homeland Security identify abnormal levels of bacteria that could signal a bio-attack. It may also give scientists more insight into the role that climate plays in the amount of bacteria in the air.
If more surveys like this are done, you may one day see some World Almanac data showing nationwide bacterial levels in various U.S. cities. But that could be years away, so don't hold your breath.
Study Finds the Air Rich with Bacteria (Lawrence Berkeley National Lab)