Question

From monitoring stations around the globe, data was collected to produce the above graphs. These graphs show atmospheric concentrations of several halogenated gases (gases that contain fluorine, chlorine, or bromine), measured in parts per trillion (ppt). Which international treaty contributed to the trends that can be seen when comparing the two graphs shown above?
Responses

A Montreal ProtocolMontreal Protocol

B Manhattan ProjectManhattan Project

C Antarctica ProtocolAntarctica Protocol

D Treaty of Versailles

Answer 1

The international treaty that contributed to the trends observed in the atmospheric concentrations of halogenated gases is the **Montreal Protocol**. This treaty, which was adopted in 1987, aimed to phase out substances that deplete the ozone layer, including many halogenated gases such as chlorofluorocarbons (CFCs). Therefore, the correct response is:

**A. Montreal Protocol**.