UV and blue light protection on sunglasses after aging process

Abstract

Most sunglasses standards require ultraviolet protection from 280 nm – 380 nm to ensure the limits for effective spectrally weighted radiant exposure. They are a mirror of ISO 12312-1 and do not consider UV-A upper limit as 400 nm. Some standards have extended the UV-A limit, however, none of them considers the World Health Organization safe limits for unweighted radiant exposure: ultraviolet radiant exposure in the spectral region 180 nm – 400 nm incident upon the unprotected eye(s) should not exceed 30 J/m2 effective spectrally weighted (based on the actinic spectra), and the total (unweighted) ultraviolet radiant exposure in the spectral region 315 nm to 400 nm should not exceed 10 kJ/m2. Calculations of these limits were performed for 27 Brazilian state capitals, and they led to a change in the upper UV-A limit to 400 nm on the 2013 review of the Brazilian standard NBR 15111:2013. Moreover, because the sunlight irradiance in Brazil is quite high, integration over the 280 nm – 400 nm range yields an ultraviolet radiant exposure (spectrally weighted) that is an average of 49% greater than that for the 280 nm – 380 nm range. Additionally, the unweighted ultraviolet radiant exposures are over the limit. Ultraviolet radiant exposure is latitude dependent. Brazil exceeds the limit of unweighted radiant exposure on average 40% – 50%. Europe and the US have a similar scenario and exceed around 40%. Furthermore, despite the blue light hazards mentioned in the literature, there are no limits whatsoever established on any sunglasses standards, and our calculations show that not only they exceed the safety limits, but they should also be included on the standards.