The thickness of ozone in a column of air in the atmosphere is measured in terms of 

Ozone concentration in the Earth’s atmosphere is commonly measured using Dobson units (DU). One Dobson
unit corresponds to a layer of ozone that would be 0.01 millimetres thick if it were compressed into a layer with uniform thickness at standard temperature and pressure conditions (STP) and spread evenly across the Earth’s surface. The average amount of ozone in the atmosphere is roughly 300 Dobson Units, equivalent to a layer 3 millimetres (0.12 inches) thick— the height of 2 pennies stacked together. By measuring the total amount of ozone in a vertical column of air, researchers can determine the ozone concentration and monitor changes in the ozone layer’s thickness and distribution. This measurement is essential for assessing the health of the ozone layer and understanding its role in protecting the Earth from harmful ultraviolet (UV) radiation.
(1) Kilobase (Kb) is a unit of measurement used in genetics to quantify the length of DNA sequences (1,000 bases).
(3) Decibels (dB) are a unit of measurement used to quantify the intensity or power of sound or other signals.
(4) Decameter is a unit of length measurement equal to ten metres.