If you live in the area surrounded by countryside, you will know that one of the most magical smell comes after a rainfall.
The smell is actually the waste products of bacteria in soil called streptomycets. As the tiny pockets of air between grains of soil get filled with water, the bacteria’s gases are pushed out of the ground an into the air. Be it a waste product, but it makes you feel better by causing a change in your brain wave pattern. How this happens is not clearly understood, but who cares?