¥Ozone can be measured by the depth of ozone if all ozone in a column of atmosphere is brought to sea-level temperature and pressure.
¥One Dobson
unit corresponds to a 0.01 mm
depth at sea-level temperature
and pressure
¥The ozone layer is
very thin in Dobson units.
¥ There are only a few millimeters (few hundred Dobsons) of total ozone in a column of air.