I.                    Ozone is one of the most important constituents of our upper stratosphere, it is generated when oxygen molecules are split into atoms by UV-C photons which then combine with other oxygen molecules to create ozone. Ozone is much better than oxygen at absorbing high energy radiation from the sun, thus protecting us from potential DNA damage.

Even though it’s presence in the upper layers of our atmosphere is welcome, ozone is toxic to humans when inhaled directly. In the lower layers of the atmosphere it is considered a pollutant. In its pure state it is said to have a very sharp smell, in lower concentrations it contributes to the characteristic smell of thunderstorms and electric arcs.

II.                 The excess of carbon dioxide in our atmosphere is arguably the biggest contributor to global warming. This colorless, odorless gas reflects IR light back to earth’s surface thus preventing radiative cooling. In order to even start reverting the damage already caused to multiple ecosystems we need to develop new ways of removing CO2 from our atmosphere.

III.                Carbon monoxide is a highly poisonous gas obtained through the incomplete combustion of various fuels. This has little to no effect on the planet’s temperature, but it can greatly affect the atmosphere’s ability to purge itself of other pollutants. It also acts, together with UV rays from the sun, as a catalyst in the formation of lower atmospheric ozone. CO also has direct negative effects on our health. It can react with hemoglobin in our blood, when this happens it bonds much more strongly than oxygen and renders the molecule effectively useless.

IV.               Sulfur dioxide is a colorless, foul smelling gas which is emitted by cars, power/processing plants and, surprisingly, volcanoes. It contributes mainly to acid rain which damages plants and all ecosystems that depend on them. In higher concentrations it can cause inflammation of the upper respiratory tract which causes discomfort in healthy adults but can lead to more serious complication in people suffering of asthma or children.

V.                 Nitrogen dioxide is a dark brown gas with a chlorine-like smell. It is another contributor to acid rain emitted mainly by cars, or other fuel burning machinery, and power plants. Its main negative effect is acid rain. It is very similar to SO2 regarding its health effects, which is not surprising considering they both belong in the same class of chemicals, acid anhydrides.

VI.               Dichlorodifluoromethane is a colorless ethereal smelling gas which was responsible for the so called “hole in the ozone layer”. This gas was widely used in aerosol cans in the 20th century and the beginning of the 21st. It had the unfortunate side effect of accelerating the decomposition of ozone. It is no longer an active pollutant and we decided to present it as a fortunate case where we were able, through new rules and regulations, to combat pollution and even reverse its effects.