Erythemal UV radiation across Nigeria: where do we stand?

The deleterious effects of solar ultraviolet (UV) radiation on humans are of public health concern which demands constant global monitoring and intervention. This study analysed the latitudinal variations in mean daily and multi-year erythemal ultraviolet radiation (EUVR) across 7 states in Nigeria using satellite data from the Total Ozone Mapping Spectrophotometer (TOMS) and Ozone Mapping Instrument (OMI). The latitudes studied were 13 degrees N, 8 degrees N, 6 degrees N and 4 degrees N respectively, using 37 years of data obtained from phases: 1979-1988, 1989-1998, 1999-2008 and 2009-2020. The data obtained were statistically analysed using Ms Excel and MATLAB. The results of this study show that the mean daily EUVR at the selected latitudes ranges from 32.97 to 390 (mW/m2). The results show that Borno State located at latitude 13 degrees N had the highest EUVR, while Rivers State recorded the least EUVR at latitude 4 degrees N. Comparative analysis of all the locations studied indicates latitudinal and longitudinal variations because the eastern axis recorded higher values than its western counterpart on the same latitude. Box and whisker plots in this study summarized the latitudinal variance in the mean multi-year EUVR in each phase. Box and whisker plots from 2009-2020 showed that there was a drastic reduction in mean multi-year EUVR in this phase unlike in the other phases. The findings of this study when compared to the UV index show that the 37 years mean EUVR obtained across Nigeria ranged from 8-10 which is on the "very high" category. This study recommends the implementation of WHO suggestions in preventing the biological effects of solar UV radiation. Furthermore, the Nigerian government should curb ignorance among its citizens by heightening public awareness of the effects of EUVR.