Assessment of Ultraviolet Radiation Exposure Levels on Selected Open Campuses in South Western Nigeria

Ultraviolet radiation from the sun is a known cause of skin damage, photokeratitis, and elevated long-term cancer risk, with exposure intensity strongly influenced by solar zenith angle, altitude, and atmospheric ozone column. This study assesses the UV index and erythemal UV irradiance levels at open areas on the campuses of three universities in Ogun, Oyo, and Lagos States, South West Nigeria. Measurements were conducted using calibrated UV radiometers sensitive to the 290 nm to 400 nm spectral range, with particular sensitivity to the erythemally weighted UV-B band. Data were collected at hourly intervals from 6:00 AM to 6:00 PM on clear sky and partially cloudy days over a three-month period spanning the dry season. The UV index was calculated from measured erythemal irradiance using the standard CIE weighting function. Maximum UV index values of 12 to 13 were recorded between 11:00 AM and 1:00 PM, classifying exposure as extreme on the WHO UV index scale. Comparative analysis between campus sites indicates that open sports fields receive 30 percent higher UV doses than tree-shaded walkways due to the absence of natural canopy shielding. The study evaluates daily personal UV dose estimates for students with typical outdoor activity patterns and compares results with recommended safe exposure limits. Recommendations for sun protection policies, shaded common areas, and UV awareness education programs on Nigerian university campuses are provided. Keywords: ultraviolet radiation, UV index, university campus, South West Nigeria, sun protection