You probably (especially if you've visited experiment E1) know that Ozone, O3, is a reactive allotrope of Oxygen. While it is very corrosive and thus toxic to life, it does have beneficial uses in certain controlled situations such as a disinfectant. Since 1930 it has been known that there is also a natural layer of Ozone high in the Earth's atmosphere, created when high energy radiation with wavelength < 240 nm (recall larger energy bundles have shorter wavelengths) strikes and dissociates O2. This high altitude Ozone layer is not harmful to life, but actually provides a beneficial service by blocking much of the high energy ultraviolet portion of sunlight which otherwise would be destructive to life.
Seemingly unrelated is another property shared by all gases: when compressed their temperature rises, and when allowed to expand and rarify, they cool. First demonstrated as a method of cooling in 1748 by William Cullen at the University of Glasgow, the cyclic compression and rarefaction was first used in a practical refrigerator built by Jacob Perkins in 1834. Only a few gases can be easily compressed enough that when allowed to re-cool to room temperature, they also condense to liquids. If such liquid is then allowed to flow and re-expand in a nearby chamber, it vaporizes, greatly expands in volume, cooling itself and the chamber as well. Pumped outside the chamber and compressed to liquid again, this gas/liquid transfers heat from inside the chamber to outside. Unfortunately the few gases which can be easily liquified are either poisonous (such as ammonia, NH3) or flammable ( such as ether, CH3CH2OCH2CH3). Following a number of deaths caused by leaking refrigerator gases, Thomas Midgely developed in 1928 the first of several non-toxic, non-flammable alternative refrigerants commonly called Freon. Because of Freon's safer properties, it has been widely used in refrigerators, air conditioners, and other heat pumps.
About 1970 chemists discovered a chemical mechanism by which Freon might catalyze conversion of reactive Ozone to more stable O2. While this might be beneficial at ground level, the immediate worry was that leaked refrigerants might slowly mix in the atmosphere and over many years reach higher altitudes, there reducing the upper atmosphere Ozone. This in turn could allow increased amounts of harmful ultraviolet light to reach ground level where it could increase skin cancers and destruction of plants. Once this was verified in 1985, a world wide effort was undertaken to stop manufacturing and using substances found to catalyze Ozone conversion and to find better substitutes. A protocol was established in Montreal in 1987 to limit production of ozone depleting chemicals. That agreement seems to be working. Between 1996 and 2002 the depletion of the ozone layer began to level off at latitudes higher than 40° in both hemispheres. It is anticipated that the slow natural decomposition of the stable Freon and the re-establishment to traditional concentrations of unstable Ozone in the upper atmosphere may take 20 to 70 years.
Communicating technical information such as observations and findings is a skill used by scientists but useful for most others. If you need course credit, use your observations in your journal to construct a formal report.