Dissimilarity in distributions of ocular exposure and environment spectrum irradiance of ultraviolet

Objective To explore the difference in the distributions of ocular ultraviolet (UV) exposure and environment UV spectrum irradiance.Methods The UV exposure levels at Sanya city of Hainan province,China were determined;a dual-detector spectrometer and a self-designed manikin with optical fiber high sensitive spectrometer were used to measure ocular UV exposure and ambient UV spectral irradiance simultaneously.The biological effective intensity (BEI) of UV irradiance were assessed based on spectrum-weighted irradiance at noon and injuries of cornea,conjunctiva,and lentil;then the UV irradiance dose was calculated with time-weighted BEI.Results The diurnal variation of environment UV irradiance reaches the maximum at 13:00 post meridiem (PM),exhibiting a unimodal distribution;however,the peak value of ocular exposure to UV irradiance is at 10:00 ante meridiem (AM) and 16:00 PM,exhibiting a bimodal distribution.The maximum wavelength of environment and ocular exposure to UV irradiance are both at 400 nm,with the dosage of 161.51 μw cm^-2 nm^-1 for environment irradiance at noon and the dosages of 65.43 μw cm^-2 nm^-1 and 66.20 μw cm^-2 nm^-1 for ocular exposure at AM and PM.Whereas,the injury-related maximum biologically effective wavelength of UV irradiance are 311 nm for cornea,300 nm for conjunctiva,and 307 nm for lentil,with the corresponding intensities of 0.30 μw cm^-2 nm^-1,0.004 6 μw cm^-2 nm^-1,and 0.44 μw cm^-2 nm^-1 at 10:00 AM,respectively.Conclusion The distributions of UV spectrum irradiance are different for ocular exposure and background environment.