Chapter 1.1, Problem 5SSC

Interpretation Introduction

Interpretation:

The reason for concern of increasing level of UVB in the atmosphere needs to be explained.

Concept introduction:

UVB rays (or type B ultraviolet) are the portion of sunlight which gives sunburn.

Answer to Problem 5SSC

UVB (or type-B ultraviolet) rays are so harmful for our environment.

Explanation of Solution

A lifetime of CFCs in the atmosphere is about 20-100 years. One free atom of chlorine from a molecule of CFC can cause damage (or it is harmful). The above-mentioned may destroy ozone molecules (O) for a long period.

The ozone layer is naturally formed by a reactive process in the stratosphere. This ozone layer of Earth blocks damaging UV rays of the sun. According to Molina and Rowland's model, as the level of CFCs will increase, it may decrease the level of ozone. Depleting the ozone layer is the main reason of increasing UVB level in the atmosphere.

Too much rise in the level of UVB (in atmosphere) is so harmful for animals, humans as well as plants. Exposure to UV radiations may cause the following diseases:

1. Premature aging of the epidermis (skin), and
2. Sun damage (wrinkles or leathery skin, spots), and
3. Dryness in plants
4. Can cause skin cancer

Conclusion

UVB rays can affect the upper layer of skin (or sunburns). It may also cause skin cancer.