- What is good ozone
- What is Bad ozone (ground-level
- The science of ozone
- Ozone depletion
graphics and images
- FAQs about ozone
- Ozone Depletion Publications, References and Resources
The Connection Between Ozone Depletion and UVB Radiation
Reductions in ozone levels will lead to higher levels of UVB reaching the Earth's surface. The sun's output of UVB does not change; rather, less ozone means less protection, and hence more UVB reaches the Earth. Studies have shown that in the Antarctic, the amount of UVB measured at the surface can double during the annual ozone hole. Another study confirmed the relationship between reduced ozone and increased UVB levels in Canada during the past several years.
Effects on Human Health
Laboratory and epidemiological studies demonstrate that UVB causes nonmelanoma skin cancer and plays a major role in malignant melanoma development. In addition, UVB has been linked to cataracts. All sunlight contains some UVB, even with normal ozone levels. It is always important to limit exposure to the sun. However, ozone depletion will increase the amount of UVB and the risk of health effects.
Effects on Plants
Physiological and developmental processes of plants are affected by UVB radiation, even by the amount of UVB in present-day sunlight. Despite mechanisms to reduce or repair these effects and a limited ability to adapt to increased levels of UVB, plant growth can be directly affected by UVB radiation.
Indirect changes caused by UVB (such as changes in plant form, how nutrients are distributed within the plant, timing of developmental phases and secondary metabolism) may be equally, or sometimes more, important than damaging effects of UVB. These changes can have important implications for plant competitive balance, herbivory, plant diseases, and biogeochemical cycles.
Effects on Marine Ecosystems
Phytoplankton form the foundation of aquatic food webs. Phytoplankton productivity is limited to the euphotic zone, the upper layer of the water column in which there is sufficient sunlight to support net productivity. The position of the organisms in the euphotic zone is influenced by the action of wind and waves. In addition, many phytoplankton are capable of active movements that enhance their productivity and, therefore, their survival. Exposure to solar UVB radiation has been shown to affect both orientation mechanisms and motility in phytoplankton, resulting in reduced survival rates for these organisms. Scientists have demonstrated a direct reduction in phytoplankton production due to ozone depletion-related increases in UVB. One study has indicated a 6-12% reduction in the marginal ice zone.
Solar UVB radiation has been found to cause damage to early developmental stages of fish, shrimp, crab, amphibians and other animals. The most severe effects are decreased reproductive capacity and impaired larval development. Even at current levels, solar UVB radiation is a limiting factor, and small increases in UVB exposure could result in significant reduction in the size of the population of animals that eat these smaller creatures.
Effects on Biogeochemical Cycles
Increases in solar UV radiation could affect terrestrial and aquatic biogeochemical cycles, thus altering both sources and sinks of greenhouse and chemically-important trace gases e.g., carbon dioxide (CO2), carbon monoxide (CO), carbonyl sulfide (COS) and possibly other gases, including ozone. These potential changes would contribute to biosphere-atmosphere feedbacks that attenuate or reinforce the atmospheric buildup of these gases.
Effects on Materials
Synthetic polymers, naturally occurring biopolymers, as well as some other materials of commercial interest are adversely affected by solar UV radiation. Today's materials are somewhat protected from UVB by special additives. Therefore, any increase in solar UVB levels will therefore accelerate their breakdown, limiting the length of time for which they are useful outdoors.
For more information on how ozone depletion affects either human health or the environment, follow the links below.
Ozone and Your Health - 1999
This short, colorful pamphlet tells who is at risk from exposure to ozone,
what health effects are caused by ozone, and simple measures that can be
taken to reduce health risk.
PDF version (448K)
Health Effects of Ozone Depletion A detailed explanation of health effects linked to to UV exposure, including skin cancer, other skin problems, cataracts, and immune system suppression.
Environmental Effects of Ozone Depletion and Its Interactions with Climate Change
This report by the United Nations Environment Programme's
Ozone Secretariat explains the effects of ozone depletion other than those on human health.
- Two minute movies summarizing the science and effects of ozone depletion created through a partnership between EPA and The Weather Channel.
Scientific Assessment of Ozone Depletion: 2002
- This is the most recent World Meteorological Organzation and United Nations Environmental Programme assessment. It contains the most up-to-date understanding of ozone depletion and reflects the thinking of over 250 international scientific experts who contributed to its preparation and review.
Twenty Questions and Answers About Ozone Depletion (2.1 MB)
- This component of the "Scientific Assesment of Ozone Depletion: 2002" presents 20 questions and answers about the often-complex science of ozone depletion. The answers were all prepared by and reviewed by a large international group of scientists. It is written for a broad readership of decision-makers, educators, students, and the
Questions and Answers (brief)
Fact Sheet (detailed)
What EPA Has Done About Ozone Depletion: An Overview
What Can Individuals Do?
On the Trail of the Missing Ozone
- This introduction to ozone depletion first describes the causes and effects of ozone depletion, and then explains some of the solutions. Follow Farley the reporter as he learns about this issue. Links are provided along the way to more detailed information found elsewhere on the site. Three versions are available: a web-viewable set of illustrated panels, a text version, and an Adobe Acrobat version.
The Ozone Depletion Process
- A broad overview of how ozone depletion occurs.
The Antarctic Ozone Hole
- View an animation of the 2000 hole, read why it occurs over the South Pole, and consider the many ways to measure the hole.
Current Progress of the Antarctic Ozone Hole
- View a page from NOAA Climate Prediction Center's web site, which shows weekly updates of the hole.
Ozone Science Crossword Puzzle
Environmental Indicators: Ozone Depletion
- Describes the data that characterize the ozone layer and demonstrate that CFCs and other chemicals are causing ozone depletion. Many internal links allow more in-depth reading.
Ozone Depletion: When Less Is Not Enough
- Written by the National Safety Council's Environmental Health Center, this guide provides a well-rounded description of ozone depletion, its causes, and its impacts. It is one chapter of a book titled
Reporting on Climate Change: Understanding the Science.
Ozone-Depleting Substances, ODPs, GWPs, and CAS Numbers
Myth vs. Measurement
- A series of responses to the most common misunderstandings about ozone depletion.
CFCs are Heavier Than Air, So They Can't Reach the Ozone Layer
Volcanoes and the Oceans are Causing Ozone Depletion
Ozone Depletion Occurs Only In Antarctica
No Link Exists Between Ozone Depletion and Higher UV Levels
Will the Ozone Layer Recover? Can We Make More Ozone?
- A response to common questions about the ozone layer's recovery.
The Effects of Ozone Depletion
- A basic description of how ozone depletion harms human health and the environment, with links to more detailed information.
Benefits of the CFC Phaseout
- This fact sheet describes specific benefits and also includes some case studies of successful use of alternatives.
Ozone: Good Up High, Bad Nearby
- Produced by EPA's Office of Air Quality Planning and Standards, this fact sheet explains the difference between stratospheric and tropospheric ozone.
- Information from Environment Canada
Stratospheric Ozone web site contains general and Canadian-focused information on ozone depletion including a
primer on ozone depletion and
indicators of ozone depletion, featuring many graphs and original data.
Stratospheric Ozone Depletion: A Focus on EPA's Research
- This brochure describes the mechanisms of and problems associated with stratospheric ozone depletion as well as some of the research projects pursued by EPA's Office of Research and Development (ORD).
Specific Aspects of Ozone Depletion
Numbering Scheme for Ozone-Depleting Substances and Substitutes
- Why chemicals are numbered certain ways.
- Ozone vs. Altitude
- Ozone concentrations are higher in the stratosphere than in the troposphere.
- Aerosols from Mt. Pinatubo
- A graph and explanation of the effects of volcanic aerosols on ozone depletion.
Ozone Depletion Over the Northern Hemisphere
- Compares Arctic and Antarctic ozone losses, along with ozone changes over North America and Arosa, Switzerland.
- University of Georgia UV Monitoring
- Information on the network of UV monitors operated for EPA.
Images and Animations
Animation of the 2003 Ozone Hole
- A brief description of the causes of the ozone hole, plus an animation of the 2003 event.
EPA's Ultraviolet Monitoring Program
- EPA operates and maintains a network of Brewer spectrophotometers throughout the United States, measuring full-sky spectrally-resolved solar radiation in the UV-B and UV-A bands. Visitors can create graphs of daily UV and ozone levels and download the data.
NASA's TOMS (Total Ozone Mapping Spectrometer) Multimedia Files: Ozone Depletion Movies, Graphics, and Original Data
- This site is full of useful data and information. Download original ozone level data and see movies and graphics of ozone depletion and the Antarctic ozone hole. The site also lets you find the ozone level over your house!
NOAA Climate Monitoring and Diagnostics Laboratory
- CMDL includes several programs to measure important atmospheric characteristics.
Nitrous Oxide And Halocompounds (NOAH) division
- NOAH measures concentrations of CFCs and other ozone-depleting substances in the atmosphere. The web site provides access to data and graphs.
Ozone and Water Vapor Group
- Provides links to several programs focusing on ozone measurement, including
vertical profiles of ozone abundance at the South Pole during the occurrence of the ozone hole and total global ozone.
NOAA Climate Prediction Center
- Includes current satellite ozone maps; UV index bulletin; TOVS data, images.
- Ozone Hole Tour
- This tour was put together by members of the Centre for Atmospheric Science at the University of Cambridge, UK. It features text, graphics, and movies.
- Ozone Images from the Department of Meteorology, University of Reading, UK
- Features a 90-day archive of the latest images from global, northern hemisphere, and southern hemisphere ozone measurements. Also features animations and ozonesonde measurements from Antarctica. Some of these images are also available from the NOAA Climate Prediction Center.
- World Ozone and Ultraviolet Radiation Data Centre
- Operated by Environment Canada, this Centre provides current and time series graphs of ozone and UV radiation over Canada and North America.
International Scientific Organizations
- World Meteorological Organization Press Releases and Bulletins
- A collection of recent bulletins about the ozone hole.
- British Antarctic Survey information
- Information from the group responsible for monitoring the Antarctic Ozone Hole, including regular bulletins on ozone levels.
- Online papers at CIESIN
- This site provides the full text of an enormous number of papers on ozone depletion.
Ozone Science Frequently Asked Questions (FAQ), Answers, and References (not maintained by EPA; thanks to Robert Parson)
This set of questions and answers provides carefully cited information. It goes into considerable detail and provides numerous references to original research. The FAQ is available at
several sites in plain text.