Ozone is made when a electric spark passes through air, and this accounts for the characteristic odor give off by some electrical motors.
Ozone is largely responsible for the discomfort associated with photochemical smog .
High levels of ozone during smog build-up can cause difficulty to people with respiratory ailments like emphysema and asthma. Ozone also damages plants and may be an important factor in the damage that is occurring to forests in Europe and North America. Satellite monitoring of the stratosphere, which began in 1978, has revealed a marked decline. The Dobson unit is a measure of the number of molecules of ozone in a vertical column of the atmosphere. You can see that the concentration of ozone decreases in ever-smaller concentric circles with the lowest reading centered over the South Pole.