As to 7→1→5→18 http://en.wikipedia.org/wiki/Ultraviolet 看到Glass似忽可以「擋」紫外線，所以就翻了一下網路上的資料， 然後發現 Ordinary glass is partially transparent to UVA but is opaque to shorter wavelengths while Silica or quartz glass, depending on quality, can be transparent even to vacuum UV wavelengths. Ordinary window glass passes about 90% of the light above 350 nm, but blocks over 90% of the light below 300 nm 所以，其實擋不擋還是要看材質。 UVA, UVB, UVC etc來說，照文章意思好像是UVA擋一部份，UVB, UVC擋掉（視材質）。 但因為UVA最弱（以hν=能量而言）所以是有擋一些的作用。 Eye High intensities of UVB light are hazardous to the eyes, and exposure can cause welder's flash (photokeratitis or arc eye) and may lead to cataracts, pterygium [9] [10], and pinguecula formation. Protective eyewear is beneficial to those who are working with or those who might be exposed to ultraviolet radiation, particularly short wave UV. Given that light may reach the eye from the sides, full coverage eye protection is usually warranted if there is an increased risk of exposure, as in high altitude mountaineering. Mountaineers are exposed to higher than ordinary levels of UV radiation, both because there is less atmospheric filtering and because of reflection from snow and ice. Ordinary, untreated eyeglasses give some protection. Most plastic lenses give more protection than glass lenses, because, as noted above, glass is transparent to UVA and the common acrylic plastic used for lenses is less so. Some plastic lens materials, such as polycarbonate, inherently block most UV. There are protective treatments available for eyeglass lenses that need it which will give better protection. But even a treatment that completely blocks UV will not protect the eye from light that arrives around the lens. 不過即使可以擋，對周圍的皮膚還是有傷害的。而且還是用塑膠的護目鏡為宜。 --

※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 76.201.144.184 ※ 編輯: Ren 來自: 76.201.144.184 (09/11 23:28)