Explain how an unbalanced translocation occurs and how it affects humans.

An unbalanced translocation is an abnormality caused by the rearrangement of parts between non-homologous chromosomes. To simplify, unbalanced translocation occurs when a child inherits a chromosome with an incomplete or extra genetic material from parent chromosomes with balanced translocations (an even exchange of genetic material and information with the chromosomes). Diseases such as cancer, infertility, and Down syndrome are caused by chromosomal or unbalanced translocation. In 1938, a paper was published by Karl Sax at the Harvard University Biological Laboratories demonstrating the effects of radiation (particularly in X-rays) to major genetic changes affecting the chromosomal translocations. The study led to the development of the field of radiation cytology. 

The answer is ozone layer.