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Sunlight & UV

Tracking Sunlight & UV

Emory University’s Environmental Remote Sensing Group at the Rollins School of Public Health provides data on sunlight and UV exposure for the Tracking Network.

Sunlight Exposure

Emory’s Environmental Remote Sensing Group combined data from the National Solar Radiation Data Base (NSRDB) and SolarAnywhere® into one dataset for analysis. Measures available include annual average sunlight exposure and monthly average sunlight exposure by state and county for the years 1991-2012.

Sunlight exposure is measured by solar irradiance. Irradiance is a measure of solar intensity in one moment in time over an area. Global solar irradiance, or GHI, is the total amount of sunlight received from above by a surface horizontal to the ground. GHI is used to calculate the sunlight exposure measures included on the Tracking Network.

UV Exposure

The Environmental Remote Sensing Group used data from the Ozone Monitoring Instrument (aboard the NASA Aura Spacecraft) to calculate UV exposure measures included on the Tracking Network. They grouped data by state, county, and year. Then they summarized the average erythemally weighted irradiance (EDR) and erythemal daily dose (EDD) separately for each group.

EDR describes the amount of UV that can cause sunburn during midday. It is measured around noon when intensity is likely strongest. EDD represents the total amount of UV radiation that can cause sunburn over the course of a day.

UV exposure data are available as annual and monthly average daily doses and annual and monthly average doses around noon. Data can be viewed by state and county levels for the years 2005-2015.

Uses for These Data

These data can be used to:

  • Understand how solar radiation levels are changing across geography and time.
  • Identify areas where intensity may be increasing.
  • Provide data to help public health officials make informed decisions about planning and implementing programs and services for people living in regions of high exposure.

Monitoring, collecting, and disseminating sunlight and UV exposure information is the first step to developing policies and educational resources that can help prevent the harmful effects related to excessive exposures.

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