Planes don't spray chemicals. But they do dump jet fuel into the air above cities when they're too heavy to land safely.
Of course if the safer option is available they'll dump it into the nearest body of water, or generally uninhabited terrain such as farmlands or forests.
That said they're flying high above and the fuel is sprayed at a slow enough rate relative to the speed of the plane that they aerosolize and just ride the wind to gently blanket the earth with their cool embrace.