Naked Science Forum
Non Life Sciences => Technology => Topic started by: paul.fr on 21/01/2009 19:33:03
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Health Canada are investigating!
Energy-saving bulbs to be tested for UV radiation
Jen Skerritt, Winnipeg Free Press
Published: Wednesday, January 21, 2009
WINNIPEG - The federal government is reviewing the safety of energy-saving light bulbs, responding to concerns the low-cost green alternative may emit potentially harmful ultraviolet radiation.
Health Canada launched a study in December to test compact fluorescent bulbs to see if they emit ultraviolet rays - less than two months after British health officials issued a public warning that, in proximity, the bulbs emit UV rays similar to outdoor exposure levels on a sunny summer day.
The United Kingdom's Health Protection Agency now recommends people should not be closer than 30 centimetres from an energy-saving light bulb for more than one hour per day, since it is like exposing bare skin to direct sunlight. The agency warns the emissions could cause problems for people suffering from medical conditions like lupus.
In Canada, the bulbs have been widely promoted as an easy way to reduce greenhouse gases and are expected to replace incandescent bulbs by 2012 after a federal ban eliminates the inefficient bulbs altogether.
Robert Bradley, Health Canada's director of consumer and clinical radiation protection, said the increased use of energy-saving light bulbs across the country prompted the review. That it comes on the heels of media fanfare over the British study is coincidental, he said.
Bradley said researchers will test whether the bulbs emit any UV rays and, if so, how intense they are. He said it's important to ensure the compact fluorescent bulbs are as safe as the old standard fluorescent tube lights.
Bradley wouldn't speculate on whether the findings could jeopardize nationwide campaigns promoting the use of the light bulbs as a green alternative.
"It's not something we've announced outright and, quite frankly, at this point in time there really isn't a lot to announce," Bradley said during a phone interview from Ottawa Tuesday.
"I'd rather have some results we can analyze and determine what if any response is required."
Preliminary results will be available by late summer or early fall.
Manitoba Hydro promotes compact fluorescent bulbs as one of the best energy-efficiency investments, since they use 75 per cent less electricity and last up to eight times longer than incandescent bulbs. The utility first started public campaigns to get Manitobans to switch to the efficient light bulbs four years ago, and continues to offer special discounts and incentives for people who purchase them.
Hydro spokesman Glenn Schneider said the utility may have to change its energy-efficient lighting programs if the federal study unearths harmful emissions from the bulbs. Schneider said Hydro hasn't received any complaints about radiation or skin damage from the light bulbs and speculates that sensitivity to light is more common in Europe than North America.
"If there's something that turns up that is of concern, then we would have to reconsider our campaigns promoting those bulbs," he said. "But I think we'll wait to see if there are any results that confirm that concern
http://www.canada.com/topics/news/story.html?id=1199852
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Sounds like nonsense to me.
You get far more UV from the Sun even on a dull day.
If you are concerned about UV never go outside.
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Are they telling us not to use energy saving light bulbs then?
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Most of the UV will be blocked by the glass envelope of the light bulb/tube. Ordinary glass blocks 90% of UV below 300nm i.e. nearly all UVB and as near to 100% of UVC as makes no odds.
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There are energy saving bulbs which emit UV light designed for use by reptile keepers.
http://www.arcadia-uk.info/product.php?pid=21&mid=12&lan=en&sub=&id=4 (http://www.arcadia-uk.info/product.php?pid=21&mid=12&lan=en&sub=&id=4)
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To put the amount of UV emitted from fluorescent lighting in context a 1993 study found that UV exposure from sitting under typical office fluorescent lights for eight continuous hours is equivalent to just over one minute of sun exposure (Lytle et al, 1993 (http://www.ncbi.nlm.nih.gov/pubmed/1343229)).
http://www.environment.gov.au/settlements/energyefficiency/lighting/publications/fs1.html
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Depending on the manufacturer and specific bulb, you can get UV light emitted from a compact-fluorescent. All fluorescent bulbs uses a mercury-discharge inside the tube which natively emits UV light, but which is converted to visbile light by the white phosphor coating on the inside of the tube. If the phosphor layer is too thin (tends to happen particularly at the ends of the tube) then some UV will escape (if you make the phosphor layer too thick then I imagine you lose light in the phosphor and reduce the brightness and efficiency, so it's probably a fine balence). Glass will very heavily attenuate the shorter-wave UV, although a non-negligible amount of UV-A (from the 365nm mercury line) can escape. That said, it must be far less than you get from a "blacklight" tube used for stage/theatrical/disco/club effects - which has no phosphor coating at all.
With some CFL lamps I have tried, I have noticed office paper in the room glowing purple and freshly washed shirts (with UV-brighteners) glowing too.
Household dust typically fluoresces under UV light, and this may go some way to explain why dark-coloured fabrics (especially navy blue) tend to look grey/dusty in the light from CFLs. That and the seriously deficient line-spectrum of the visible output. (Disclaimer: I strongly dislike the colour-rendering of fluorescent lamps and will be stockpiling proper bulbs.)
I suspect the dangers of UV from CFLs are well over-stated, although that UV is still undesireable for aesthetic reasons (and to prevent furnishings from fading).
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I believe it is possible to photograph the UV emission from a CFL ...
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http://www.thenakedscientists.com/HTML/content/kitchenscience/exp/colours-in-cds/
I suspect the violet line in this spectrum is caused by UV and was not visible to the eye but has been recorded
by the camera as a false violet colour. Cameras, film & digital, can "see" UV, human eyes cannot.
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Spectra from another website which seems to confirm the violet line is actually UV (~400nm)...
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http://ioannis.virtualcomposer2000.com/spectroscope/amici.html#1fluop
According to this site (http://rohr.aiax.de/chapter%202%20Refractor%20Design.htm) 436nm is "the approximate limit of human vision at shorter wavelengths,
i.e. a 400nm line would not be visible to the human eye.
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Some old people are able to see UVA. Something to do with aging of the lens in the eye.
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Some old people are able to see UVA. Something to do with aging of the lens in the eye.
If they've had cataract surgery to remove the lenses from their eyes ...
Aphakia is the absence of the lens of the eye... Aphakic people are reported to be able to see ultraviolet wavelengths that are normally excluded by the lens. This may have had an effect on the colors perceived by artist Claude Monet, who had cataract surgery in 1923.
http://en.wikipedia.org/wiki/Aphakia