Many of the chemicals used in place of CFC propellants are safe for the environment. Environmental agencies require extensive testing before a chemical can be used as a propellant. If a chemical that was deemed safe should later prove to be harmful, government regulations require that use of the chemical must cease. Look at the image of the hole in the ozone layer. Measurements taken in some summer months have shown ozone levels over the southern ice cap to be well in excess of 300 DU, a full 100 DU more than the levels recorded in 1996, when the hole reached record size.
Volcanoes do produce chemicals which break down ozone.
However, volcanic eruptions do not have the power to send these chemicals into the upper atmosphere, and the sheer mass of many of these chemicals causes them to fall quickly from air currents to the Earth. Ocean chlorine tends to stay in the ocean. The oceans have been around since the ozone layer formed, which would seem to indicate that it certainly does not hinder the ozone equilibrium in the atmosphere. Back to top Q uiz Click here to take the Ozone quiz. Please use your browser's back button to return to the Ozone teacher's guide.