Special Sub-Topic: Punta Arenas vs. The Ozone Layer Authored by: Flynn_17 Sub-topic of: Chile

Punta Arenas is a port city in Patagonia, in South America. It is in mainland Chile, and lies on the southern coast, far away from any other large towns or cities. On what body of water does Punta Arenas have a coastline?

Strait of Magellan. Punta Arenas is the world's southernmost large city, and has a population of around 117,000 people. It is also known as Magellanese, and is twinned with the town of Bellingham, Washington. Only Ushuaia is further south that Punta Arenas, but it is a small town with a population of only 30,000.

The ozone hole over Punta Arenas gets larger and smaller in cycles, meaning that the ozone layer is thinner in October than in any other month.

t. The thickness of the ozone layer increases and decreases steadily, but in October, it is thinner than at any other time of the year. For this reason, the people of Punta Arenas operate a light system; a red light means a high UV day, whereas a green light means a low UV day.

Picture yourself in Punta Arenas. The sky is white, but it is still the same temperature as it was yesterday. The sunlight is incredibly bright, almost blinding, and it reflects off of cars and the sea. Is this a red light day (when there is almost no ozone over Punta Arenas), an orange light (when the ozone is getting dangerously thin), a yellow light day (when the ozone is thinner than usual), or a green light day (when the ozone coverage is normal)?

red&red light&red light day. Each day, the people of Punta Arenas are informed about the light status so that they can use protection against the sun. Even though the protection is offered, however, few people use it as they should.

Because of the hole in the ozone layer, there is a high rate of skin cancer in Punta Arenas. How much higher is the chance of getting cancer in Punta Arenas compared to anywhere else in the world?

Three times more likely to get cancer. Because of the lack of ozone layer, dangerous UV rays penetrate the atmosphere and shine down on Punta Arenas. This means that skin cancer is three times as likely in Punta Arenas that anywhere else in the world.

Even though the sun emits UV rays, there is still a large demand for another source of UV light in Punta Arenas. What amenity that also emits UV are we talking about?

Sunbeds (Tanning Beds). Presumably, the people of Punta Arenas assume that if they have a tan, they are less likely to get skin cancer, but there is an inherent risk with using sunbeds (tanning beds). They emit dangerous UV radiation, which is the primary cause of skin cancer.

When the hole in the ozone is directly above Punta Arenas, an area of Antarctica is also badly affected. Which area of Antarctica is worst affected when the ozone hole is in this position?

Graham Land. This is a large peninsula, and is the area of Antarctica closest to Chile and Punta Arenas. Also badly affected are the South Shetland and South Orkney Islands, which are British islands.

Punta Arenas, although a large city, was not always a settlement. In fact, it was built in 1848 to make sure that Chile got a share of the land that is known as Patagonia (and therefore retain an important trade route). What country did Chile compete with to keep this land?

Argentina. Punta Arenas is now an important port for Chile, and serves as the starting point for many expeditions to Antarctica.

On a trip outside in Punta Arenas, tourists (as well as the locals) are advised to wear sunscreen to ward off the damaging UV light. What is the minimum factor of sunscreen people are advised to use while in Punta Arenas?

Factor 30. This is the minimum factor of sunscreen needed in all of Chilean Patagonia, as the UV factor is very high all over this area. The temperatures are very low, however, so the 'Enjoy Chile' vacation guide also suggests that you pack a Polar Anorak and warm socks.

The ozone hole covers a large area of Antarctica and Patagonia, as we have discussed in previous questions. The hole has been estimated at 26,000,000 (26 million) square kilometres in size. This is about the same size as which continent?

North America. The size of the hole is expected to decline within the next 30-50 years as the amount of chlorine in the atmosphere is decreasing. This is because CFC gases (chlorofluorocarbon gases) are being used less in an effort to prevent further ozone depletion.

Ozone thickness is measured in Dobson Units, where 0.1mm equals one Dobson Units. Ozone levels in the rest of the world are usually around 400 Dobson Units, or 4mm thick, but how thin has the ozone layer over Punta Arenas been known to go?

98 Dobson Units. As the thickness goes up, the amount of UV reaching earth decreases, so the Dobson Units reading would not go up. On this day, the 29th of September 2000, the people of Punta Arenas were told not to go outside, for their skin would burn in seven minutes. In some places, a red light warning was given out to say that skin would burn ever faster, in as little time as five minutes.