Reasons

Earth's polar regions are very sensitive to pollution because of their extremely cold temperatures--the optimal environmental for compounds such as chlorofluorocarbons to increase their ozone depleting potential. In addition, it takes materials much longer to break down in colder temperatures.

Harm to Wildlife

Much of the wildlife that exists in polar regions have evolved the ability to store a lot of energy by means of fat. Persistent pollutants such as toxic metals tend to accumulate in animal fat.

Ozone Hole

In 2009, the average size of the Antarctic ozone hole hovered around 24 million square kilometers in total area.

Geography

Natural wind patterns and ocean currents carry pollution to the poles, especially the Arctic. Other important sources of pollution in the Arctic include industrial production in adjacent countries Canada and Russia. In Antarctica, pollution tends to come from maritime vessels spilling oil.

Effects

Because of their sensitivity to pollution and the global warming effect (pollution trapping heat in the atmosphere), both of the polar regions are experiencing abnormally high temperatures that are melting once permanent ice shelves.

Source:

CARC.org: Arctic Pollution: How Much is Too Much?

TheOzoneHole.com: The Ozone Hole 2009

National Resources Defense Council: Global Warming Puts the Arctic on Thin Ice

More Information:

CoolAntarctica.com: Human Impacts on Antarctica and Threats to the Environment - Pollution