There isn't a SI unit particularly for this. It would just be expressed as so many parts per million, or sometimes chemists use mg/kg which would be the same thing, or mg/liter if dealing with liquids. The standard for measuring any quantity of atoms or molecules is the mole. It is not uncommon to see "linear ozone density" expressed in Dobson units, based on characteristic absorption on a path. Along the lines of the Beer Lambert law...
An acre is over 43 thousand square feet in area. It is a unit of measure that was created to measure land.
The unit of measure for gold dust is typically in grams or ounces. These units are used to determine the weight and value of the gold dust being traded or sold.
Traditionally the unit is the fathom (=6 feet) but nowadays you will see metres or indeed any proper unit of length.
The unit of measure used to quantify the Earth's heat is the joule (J), which represents energy. Energy inputs and outputs related to the Earth's heat are often measured in joules to understand energy balance and temperature changes.
One Okta = One eighth of the sky covered by cloud.
The Dobson unit (DU) is used to measure the total amount of ozone in the Earth's atmosphere. It is a unit of measurement for the total column thickness of ozone in a vertical column of air from the surface to the edge of space. Researchers use specialized instruments like spectrophotometers to measure the concentration of ozone in the atmosphere in Dobson units.
Ozone depletion is not worse in cities. If you measure the effects of ozone depletion by the number of people affected, there are more people per unit area in cities. Ozone depletion affects every unit area more-or-less equally. Ozone pollution affects cities worst, since NOx is mostly produced by urban and suburban<->urban traffic.
"Concentration."
Atmospheric ozone concentration is measured in parts per million.
j19724
The acceptable ozone is 300 to 50 Dobson unit. It is present in the stratosphere.
Ozone depletion can be controlled by curbing CFC's. They are the main reasons behind ozone depletion.
There are various measures to control ozone depletion. Curbing CFC's is one of them.
As far as I am aware, CO is not a unit of measure.
A unit can be a measure of length. It is one-dimensional. A squared unit can be a measure of area. It is two-dimensional. A cubic unit can be a measure of volume. It is three-dimensional.
This depends on what unit you are using to measure in. However, area will always be measure in (unit)^2.
The international (SI) unit of mass is the kilogram.