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Make your own UVB Vitamin D lamp for 40 dollars - Jan 2019

Vitamin D from low-cost UVB lamps has the following update

Founder of VitaminDWiki bought a GE lamp fixture Jan 2019 and used UVB bulk from previous Light Year 2 fixture
Bulb is said to last 4,000 hours, so UVB bulb would cost 1 cent per hour
GE 16466 Basic 18 Inch Fluorescent Under Cabinet Amazon $13
G15T8E 15W Germicidal UV-B Fluorescent Lamp $25 including USPS to Seattle
OR    Ushio BC3286 USHIO G15T8E 14.7W Midrange UV Fluorescent Lamp Amazon $38
Put the bulb and fixture at top of a ladder (near the ceiling) and measured UVB at chest level 7 feet from bulb

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Similar reading with a direct view of the bulb and with reflector made with aluminim foil placed between the ceiling and the wall
8 IU per minute: UVB Meter calibrated for 20% of skin area for a 20 year-old (approximately face and hands)
500 IU per hour - 20 year-old
5,000 IU per 10 hour- 20 year-old
1200 IU per 10 hours for a senior (assumes 1/4 as much UVB created Vitamin D)
It appears that the celing paint, by itself, does not reflect any UVB
As expected, the plastic bulb cover on the GE fixture is opaque to UVB
UVB intensity at 2 feet across countertop
Countertop might reflect, so reading would be lower if no countertop
Intensity 85 @ 2 feet with reflector
5,300 IU per hour - 20 year-old, 1300 IU senior
Warning: Start with very short durations
Try one day at ~3 minutes, and see if get UV burn/pinking the following day
Double the time each day,until get slight burn/pinking the following day, then reduce the duration (perhaps by 1/3)
Note: Burning is more likely if:

  1. Low blood level of Vitamin D
  2. Same portion of skin had had UVB dose in past few days

Closeup photo of Al foil reflector

See also