The characteristic smell in the air that follows a recent shower is down to bacteria. These didn't come down in the last shower (!) but instead they're a family of ubiquitous filamentous soil-dwellers called the actinomycetes. This bacterial species make tiny "spores", which are metabolically inert or dormant forms of the bacteria and which remain resident in the soil when the ground dries out.
The purpose of these spores is to enable the organism to survive dessication and other severe conditions for extended periods of time. When it rains the water hitting the ground ejects millions of them into the air where they drift up peoples' noses, contributing to the fresh and earthy smell of a recent shower.
As a rule they don't pose a threat to humans - at least not to people with a healthy immune system - and making the air smell is not their primary goal. What will actually happen shortly after the shower is that the newly uncovered and dampened spores will settle back onto the ground and germinate. So you could look upon this process as part of the way that they disperse and spread themselves around the planet.
The purpose of these spores is to enable the organism to survive dessication and other severe conditions for extended periods of time. When it rains the water hitting the ground ejects millions of them into the air where they drift up peoples' noses, contributing to the fresh and earthy smell of a recent shower.
As a rule they don't pose a threat to humans - at least not to people with a healthy immune system - and making the air smell is not their primary goal. What will actually happen shortly after the shower is that the newly uncovered and dampened spores will settle back onto the ground and germinate. So you could look upon this process as part of the way that they disperse and spread themselves around the planet.
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