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Prolonged optical exposure to sunlight, especially intense ultraviolet light, may be linked to cortical cataracts, [52] [15] and high levels of visible light is maybe linked to macular degeneration. However, significant daily exposure to bright light may be necessary for children to avoid myopia (nearsightedness). [53]
An open (single envelope) CFL [12] An encapsulated/closed (double envelope) CFL. Some fluorescent lamps emit ultraviolet radiation. [citation needed] The Health Protection Agency of the United Kingdom has conducted research concluding that exposure to open (single envelope) compact fluorescent lamps (CFLs) for over 1 hour per day at a distance of less than 30 cm can exceed guideline levels as ...
These lamps emit ultraviolet light with two peaks in the UVC band at 253.7 nm and 185 nm due to the mercury within the lamp, as well as some visible light. From 85% to 90% of the UV produced by these lamps is at 253.7 nm, whereas only 5–10% is at 185 nm. [39] The fused quartz tube passes the 253.7 nm radiation but blocks the 185 nm wavelength.
The UV-B flux is 2–4 times greater during the middle 4–6 hours of the day, and is not significantly absorbed by cloud cover or up to a meter of water. [47] Ultraviolet light, specifically UV-B, has been shown to cause cataracts and there is some evidence that sunglasses worn at an early age can slow its development in later life. [18]
Exposure to non-ionizing ultraviolet light is a risk factor for developing skin cancer (especially non-melanoma skin cancers), sunburn, premature aging of skin, and other effects. Despite the possible hazards it is beneficial to humans in the right dosage, since Vitamin D is produced due to the biochemical effects of ultraviolet light.
UV-B lamps are lamps that emit a spectrum of ultraviolet light with wavelengths ranging from 290–320 nanometers. This spectrum is also commonly called the biological spectrum due to the human body's sensitivity to light of such a wavelength. [1] UV-B light does not tan the skin very much, compared to the UV-A lamps that are used in tanning beds.
In the average human adult it is estimated that 50 to 70 billion cells die each day from apoptosis. One of the largest promoters of apoptosis is exposure to ultraviolet (UV) light. While UV light is essential to human life it can also cause harm by inducing cancer, immunosuppression, photoaging, inflammation, and cell death. [1]
When evaluating ultraviolet germicidal lights, eye and skin health are primary concerns. UV-B, predominantly responsible for the harmful effects of sunlight, poses the highest risk for erythema, photokeratitis, sunburn and skin cancer. [15] [16] [17] While longer UV-C wavelengths and UV-A can also cause damage, their effects are less severe ...