The ozone layer is being damaged by pollutants in the air that are mostly man-made, such as chlorine and bromine. The ozone damage occurs in the stratosphere and troposphere. The lower pollution in the troposphere has many of the same causes as the upper destruction, but causes more visible and health-related issues than the stratosphere damage.
The damage to the lower atmosphere is actually an increase in what is considered bad ozone. This ozone damages plants and causes breathing issues for some people. One of the most common forms of this is called smog and is often produced from cars. There are numerous pictures of cities such as Los Angeles where the air appears brown from the smog and pollution created by the high number of people and cars in the city. The city even issues smog alerts to warn people when the levels of the pollution are unsafe for travel for people with breathing problems.
The damage to the upper atmosphere and what is referred to as good ozone has more long term effects on the planet. With the loss of the upper ozone, the Earth's protection against UV rays is reduced and the chance for genetic damage is increased. There have been some attempts to reduce emissions to slow the damage, such as regulating vehicles and removing types of aerosols that were high in CFC's, but much debate remains on the correct course of action to correct the issue.
Chlorofluorocarbons and other gases that have the potential to damage the ozone layer are highly regulated. During the 1970s and 1980s, the depletion of the ozone layer was linked to these gases, and countries around the world signed treaties to limit or eliminate their use. However, chlorine and bromine atoms can survive in the atmosphere for decades before breaking down, which has resulted in a continuing depletion of the ozone layer long after the regulations went into place.
The depletion of the ozone layer has led to a thinning and a reduction in its ability to block ultraviolet radiation. There are also gaps in the ozone layer, specifically over the Antarctic region. The hole in the ozone layer fluctuates throughout the year, sometimes expanding over parts of South America. Those in the regions affected by hole in the ozone face increased risks of cancer. The ozone hole can also be harmful to crops and livestock.