It was introduced in 1992 & the record 43.3 was set in the high Andes, where stratospheric ozone levels are naturally low
The Final Jeopardy clue for October 7, 2025, pointed contestants toward a scientific measure linked to solar radiation, environmental conditions, and record-setting data in high-altitude regions.
What is the UV Index?
The correct response, “What is the UV Index?”, refers to the internationally recognized scale that measures the intensity of ultraviolet radiation from the sun at a particular place and time.
The UV Index was introduced in 1992 by Environment Canada and later adopted globally by the World Health Organization, the United Nations Environment Programme, and the World Meteorological Organization. Its purpose is to inform the public of the level of UV radiation exposure on a given day and promote safety measures to protect skin and eyes from potential harm.
Understanding the UV Index and Its Origins
The UV Index is a standardized measurement of the strength of sunburn-producing ultraviolet radiation at a specific place and time. It typically ranges from 0 (minimal risk) to 11+ (extreme risk). The index was created in response to growing concern about skin cancer rates and the thinning ozone layer, which acts as Earth’s natural shield against UV rays.
Initially developed for public health communication, the UV Index quickly became an essential part of weather reporting in many countries. It offers a numeric scale, often accompanied by color codes, to guide behavior—such as applying sunscreen, wearing hats, or avoiding midday sun. The UV Index takes into account factors like solar elevation angle, cloud cover, and surface reflection, but one of the key environmental drivers is stratospheric ozone concentration.
Why the Record Was Set in the Andes
The record value of 43.3 was documented in the Andes Mountains, one of the world’s highest-altitude inhabited regions. This extreme number is significantly beyond the typical maximum of 11+ seen in lowland or coastal areas. At high elevations, the thinner atmosphere allows more UV radiation to reach the surface. The Andes are also subject to naturally low ozone concentrations due to atmospheric circulation patterns and seasonal variability.
The reading of 43.3 was recorded in 2003 near Licancabur volcano on the Chile-Bolivia border. Scientists used specialized UV sensors to monitor solar radiation levels during a period of intense solar activity and reduced ozone. While this reading is not typical for daily forecasts, it highlighted how extreme conditions can occur in certain geographic and atmospheric contexts.
The Impact of Low Ozone on UV Exposure
Stratospheric ozone plays a vital role in absorbing the sun’s harmful ultraviolet rays. When ozone levels drop—whether due to natural variability or human-caused depletion such as from chlorofluorocarbons (CFCs)—more UV-B radiation reaches the surface. UV-B is the type most responsible for skin damage and increased cancer risk.
The Antarctic ozone hole is the most prominent example of severe depletion, but high-altitude tropical regions like the Andes also experience periodic ozone thinning. The combination of altitude, thin atmosphere, and localized ozone dips make these areas prime candidates for record-setting UV Index values.
Public Health and Global Monitoring Efforts
The introduction of the UV Index in 1992 has had a lasting impact on public health education around sun safety. Today, UV Index data is widely available through weather apps, government websites, and public signage in tourist-heavy regions. The goal is to raise awareness and reduce the incidence of skin-related health issues caused by UV exposure.
Scientists continue to monitor UV radiation levels worldwide using satellite instruments and ground-based sensors. The high Andes reading of 43.3 remains an outlier but serves as a reminder of how environmental and atmospheric factors can converge to create extreme conditions. The clue on Jeopardy highlighted not just a record, but an important tool in global health and environmental awareness