Report on Cataract Incidence in the United States: Protecting the Ozone Layer Protects Eyesight
EPA Model Gains Ability to Estimate Cataract Cases Avoided
EPA uses the Atmospheric and Health Effects Framework (AHEF) model to estimate skin cancer cases and deaths avoided by protecting the ozone layer. EPA’s peer-reviewed report, released July 30, 2010, shows that AHEF now has the capability to model avoided cataract cases due to the following updates:
- Improved spatial resolution; and
- Improved information on the biological effects of UV radiation, including dose-response data by skin type and gender.
AHEF is used to model the health benefits of various policy changes. For example, in the report, EPA used AHEF to estimate the additional avoided cataract incidence by strengthening the original Montreal Protocol on Substances that Deplete the Ozone Layer through the Amendments of 1997:
- These results showed preliminarily estimates of more than 22 million additional new cataract cases avoided for Americans born between the years 1985 and 2100.
The results modeled two overarching trends when comparing less protective policies for protecting the ozone layer to more protective policies:
- Counties with large population groups older than age 55 see greater changes in cataract incidence.
- Northern latitudes see greater changes in UV exposure than southern latitudes, due to a greater decrease in column ozone.
The sensitivity analysis found that changing the biological amplification factor (BAF) by skin type and gender was not highly influential. The BAFs-- the dose-response relationship between UV radiation intensity and cataract cases caused --were the greatest source of uncertainty.
More Work Still Needs to be Done
During the next several years, EPA plans additional updates to AHEF to further improve its capabilities:
- The emissions scenarios in AHEF will be updated to be consistent with the most recent World Meteorological Organization (WMO) projections of ozone layer recovery, and provide results that reflect the Montreal Protocol as adjusted in 2007.
- EPA may be able to enhance the model’s exposure estimates considering behavior, solar zenith angle, and age.
- Access the full report: Protecting the Ozone Layer Protects Eyesight – A Report on Cataract Incidence in the United States Using the Atmospheric and Health Effects Framework Model (68 pp, 1.52 MB, About PDF)
- Learn how to prevent cataracts from EPA's SunWise Program (2 pp, 958 KB, About PDF)
- More information on Cataract Awareness Month and cataract symptoms from Prevent Blindness America.