How does the ozone layer protect us from UV radiation?
The ozone layer is a naturally occurring concentration of ozone molecules in the upper atmosphere. Unlike ground-level ozone, ozone in the upper atmosphere is not a pollutant and does not damage human health. The ozone layer protects us from harmful UV rays. The use of synthetic ozone depleting substances (ODS) has reduced ozone levels in the upper atmosphere. These are chemicals that were once used in refrigeration, fire extinguishers, and aerosols. Because the ozone layer is thinner than it used to be, more UV rays reach the Earth’s surface, leading to higher rates of skin cancer. The United States and other countries are working to phase out the use of ODS. Thanks to these efforts, the ozone layer has not become thinner since 1998 and has started to recover. Because ODS can remain in the atmosphere for 50–100 years, scientist predict that ozone will not return to pre-1980 levels until the second half of the 21st century. Car and home air conditioners and refrigerators may contain OD