comparative assessment obtained by a fluorescent lamp True-Light® 36W generated radiation and it's photo biological effetcts to the natural reference radiation in the UV

1. 1
03.05.2005
Comparative assessment
obtained by a fluorescent lamp (True-Light N7-1A-36 W)
generated radiation and its photo biological effects
to the natural reference radiation in the UV
Dr.-Ing. Mehmet Yeni / TU Berlin

2. 2
1. Health effects of UV radiation
The irradiation of human skin with solar or artificial UV radiation can cause both health benefits
and harmful effects. The occurrence of these desirable and undesirable effects depends on
the spectral composition of the radiation, the dose and the frequency of administration. For the
evaluation of artificial radiation sources are all potential health effects have to be balanced.
The UV-erythema as a symptom presents itself as an acute inflammation of human skin as a
consequence of a too high UV irradiation. This clinically known as dermatitis solaris ,
erythema solaris and effect is the best known physiological, reversible reaction of the skin to
radiation over the entire UV spectrum. Depending on the erythema reaction to the skin can
range from a mild sunburn to severe burns.
The evaluation of the spectral irradiance with the action spectrum of the UV erythema
according to DIN / 1 / and the numerical integration over the wavelength gives the
erythemal irradiance:
400 nm
Eer = ∫Eλ(
250 nm
λ) ser (λ)dλ (I)
From the spectral irradiance results in the respective, threshold irradiation times for the UV
erythema (ts, s) according to DIN / 1 / for the
skin types II:
t s,er =
250Jm -2
E
(II)
er
For the erythema-effective irradiation Eer is valid accordingly ago with the irradiation duration
t and the erythema effective irradiancy (I):
t
Her = ∫Eer (t')dt'
0
(III)
The value of the minimal erythema dose (MED) is defined in DIN with 1 MED = 250 Jm-2
and
corresponds to the threshold dose for the UV erythema Hs, er = 250 Jm-2
for the light-skinned
Europeans without pre-irradiation.

3. 3
With regard to the protection of working people in the surroundings of a radiotherapy device
and UV to emitting radiation springs limit values are to be kept. For the ocular protection - also
of the irradiated person - the limit values of her arise
effective radiotherapy strength according to:ß:
400 nm
Eeye = ∫Eλ(
250 nm
λ) seye (λ)dλ (IV)
Is the action spectrum seye(λ) in the regulations of the BG and the ICNIRP /2/ fixed.
By the vitamin D3 photosynthesis as a result of UV exposition in the human skin are
connected a row of health-supporting effects. Vitamin D deficiency is now considered one of
the main causes of rickets in children, osteomalacia, osteoporosis and muscle weakness.
Chronic vitamin D deficiency can have serious consequences as high blood pressure,
sclerosis, formation of colon, prostate, breast and ovarian cancers and diabetes type 1 result.
Numerous secured studies prove that by artificial UV irradiation in the action spectrum that
vitamin D3-Photosynthese therapeutic successes are observed with symptoms enumerated
above. The Vitamin D3 effective radiotherapy strength Evd can be looked as a measure of the
bio positive effects of the ultraviolet rays,
and the danger is to be taken into consideration by ultraviolet rays with.
400 nm
Evd = ∫Eλ(
250 nm
λ) svd (λ)dλ (V)
2. Comparative spectrum in the UV
For defined states of the sky and concrete solar heights corners the spectral radiotherapy
strengths of the authoritative sun E(λ)ref which serve as a basis of evaluation of artificial UV
springs have been defined by CIE/3/ and DIN /4/ of German Institute for Standardization.
The reference spectral distribution in the UV, accepted here, is valid for the verticalness for
radiation course by the atmosphere (midday sun at the equator) with very clear sky conditions
with small turbidity and large ranges of vision. As comparison of the erythema effectiveness
of artificial radiation sources with the natural radiation the sun erythema factor fSE is used .
In this case, a value of 300 mWm-2
is scheduled for the maximum erythemal irradiance of the
global radiation:

4. 4
fSE
Eer , Emitter
Eer ,Ref
Eer ,Emitter
0,3 Wm-2
(VI)
3. The lamp True light N7-1A-36W (2370 lm)
Illustration 1 clarifies the relative spectral process of the irradiancy in the UV and VIS of a
shining material lamp (True light N7-1A-36W/2370 lm).
Comparing the spectral irradiance values of the lamp at a geometric distance between the
application level by the lamp of Figure 2 d are m = 1.25 and the reference solar radiation in the
UV plotted on a logarithmic scale
*
. The spectral erythemal irradiation values of a fluorescent
lamp (True-Light N7-1A-36 W / 2370 lm) and the natural reference size is depicted in Fig 3.
Figure 1 Relative spectral irradiance in the UV and VIS in the application level
d = 1.25 m (True-Light N7-1A 36W / 2370 lm)
* : The spectral irradiance values of the lamp according to the manufacturer

5. 5
Picture 2: Spectral radiotherapy strength of the True-Light N7-1A-36W in one
application level (d = 1.25 m) and the authoritative suns radiation in the UV
Figure 3. Spectral erythemal irradiance of the True-Light N7-1A-36W in an application layer
(d = 1.25 m) and the reference solar radiation

6. 6
From the spectral values of irradiance is effective irradiances for defined photobiological
effects as the UV erythema, eyes vulnerability and vitamin D3 photosynthesis can be
numerically determined (see Table 1).
The lamp has the specified geometric distance in the UV-A at an irradiation intensity of
6.0•10-2
Wm-2
. By the light source in the UV-B and an irradiation intensity of 6.9•10-3
Wm-2
is
produced in the same application level. In these spectral ranges the irradiance generated by
the reference sun by a factor of approximately 1000 (UV-A) or 280 (UV-B) are greater than
those of the lamp. The relative spectral gradient of the light spectrum is increasing as in the
natural benchmark to longer wavelengths.
NO radiation is emitted by the lamp UV C (λ≤ 280 nm). In the said application layer
(d = 1.25 m) through the lamp, the illuminance Ev = 61 lx generated.
With an erythema-effective irradiancy Eer of the lamp of 2,8•10-3
Wm-2
and a sun erythema
factor of 9,3•10-3 the threshold dose for the UV erythema is reached after approximately 1500
h exposition (reference sun: 17 min).
The vitamin D3 effective irradiance of the given light source is at a distance of 1.25 m between
the lamp and the application level 3.6•10-3
Wm-2
(reference solar radiation 0.8 Wm-2
).
With direct radiotherapy of the eyes by the lamp in the distance of 1.25 ms the threshold time
for ocular damage is Hs,e ye = 336 min.
To generate an illuminance of Ev = 1000 lx on an application level (eg. as on an office desk)
theoretically 16.4 lamps of the investigated type are required. For this theoretical case of a
erythemal irradiance of Eer = 4.5•102
Wm-2
can be specified and a threshold irradiation time
required to reach a reddening of the skin as a result of UV-erythema of ts,er = 93 min on this
surface.
Besides, the Vitamin D3 effective radiotherapy strength amounts to 5.8•10-2
Wm-2
.
Conclusion:
On account of the UV-A-and UV B issue by the lamp True-Light N7-1A-36W application level
becomes by the valued lamp with given one as a Vitamin D3 effective radiotherapy strength
generally health-supporting to be looked of Evd = 3.6 mWm-2
in given application level
generates. his value is higher than the erythemal irradiance produced by the lamp Eer = 2,8
mWm-2
.

7. 7
To prevent adverse health effects, the threshold irradiation times especially for eye damage and UV
erythema are observed.
Table 1 Photo biological evaluation parameters of the True-Light lamp and the
reference solar radiation in the UV
Size
True-Light
d = 1,25 m
True-Light
da Ev = 1000 lx
Reference solar radiation
EUV-A (315 nm-400 nm) in W/m² 6,0·10-2
0,95 62,8
EUV-B (280 nm-315 nm) in W/m² 6,9·10-3
0,11 1,95
EUV-C (250 nm - 280 nm) in W/m² <10-5
<10-5
0,0
EUVEye (250 nm - 400 nm) in W/m² 0,07 1,06 64,4
EErythem (250 nm - 320 nm) in W/m² 2,8·10-3
4,4·10-2
0,21
EErythem (320 nm - 400 nm) in W/m² < 10-4
6,7·10-4
4,3·10-2
EErythem (250 nm - 400 nm) in W/m² 2,8·10-3
4,5·10-2
0,25
t erythem in min 1492 93 17
EEye (250 nm - 400 nm) in W/m² 1,5·10-3
2,4·10-2
0,25
t Eye in min 336 21 2
EVit-D3 (250 nm - 400 nm) in W/m² 3,6·10-3
5,8·10-2
0,43
Sonnenery them factor fSE 9,3·10-3
0,15 0,8
Letteratura:
/1/ : DIN 5050: Solariums and home suns, part of 1: measuring procedure, type
organization, marking
/2/ Guidelines on limit of exposure ton of lasers radiation of wavelengths between 180
nm and 1000 µm. ICNIRP Guidelines. Health Physics, November 1996, VOL. 71,
No. 5
/3/: CIE Publication No. 85, solarly Spectral Irradiance, 1989
/4/: DIN 67501, Experimental evaluation of the erythema protection of external sunning
protective agents for the human skin, 09.1999