219
Iww!3ANDvIEws
Tanning with UVB or UVA: an appraisal of risks B. L. DifTey+ Regional Medical Ph@cs Departmenq Dryburn Hospital, Durham DHl STW (U.K.)
P. M. Farr Department of Dermatorosr/, Royal Victoria In@mary, Newcastle upon m WK.1
NEI 4LP
1. Introduction Prior to the mid-l 970s the only way of achieving a tan from an artificial source was to use a sunlamp. This was invariably an unfiltered medium or high pressure mercury arc lamp which emitted a broad spectrum of optical radiation from WC (200-290 nm) through to visible and IR radiation. Because of the high WC and WB (290-320 nm) emission, exposure times were short, typically a few minutes. These lamps were inefficient in tanning and it was not uncommon for overexposure to occur resulting in acute eye damage or skin erythema and blistering. Following the development of WA (320400 run) fluorescent lamps it became feasible to induce a tan with WA radiation. In the late 1970s and early 1980s it was suggested that a tan induced by WA was safer than that induced by WB. The tanning industry was quick to seize on this perceived benefit of WA and, as a consequence, WA lamps with minimal or no WI3 content were promoted. Whilst we do not condone tanning, we present arguments which indicate that those people who do wish to tan with arti.flcial sources may be better advised to use lamps in which the WB component, rather than the WA component, contributes the major fraction towards tanning. We consider four different types of lamp and discuss the biological and clinical consequences of tanning with lamps in which either WA or WI3 is the dominant wave band.
2. Lamp characteristics The lamps considered are a medium pressure mercury lamp, a type I WA lamp (e.g. Philips TL09), a type II WA lamp (e.g. Philips TLlO, Mutzhas WASUN) and a ‘simulated sunlight’ lamp. The latter lamp is one in which the ratio of WA to WI3 is similar to that in terrestrial sunlight and in which the W irradiance is such that the time required to achieve a minimal erythema is comparable with sunbathing in summer sunshine at mid-latitudes, i.e. +Author to whom correspondence
should be addressed.
220
NJZWSAND VIEWS
TABLE 1 Characteristics of different UV lamps used for tanning Lamp
Mercury arc sunlamp Simulated sunlight lamp Type I UVA lamp Type II UVA lamp
Radiation emission (%) 1 UVA UVB UVC
UVA
UVJ3
UVC
40 95 99 > 99.9
0 20 60 z-90
35 80 40
Iww!3ANDvIEws
Tanning with UVB or UVA: an appraisal of risks B. L. DifTey+ Regional Medical Ph@cs Departmenq Dryburn Hospital, Durham DHl STW (U.K.)
P. M. Farr Department of Dermatorosr/, Royal Victoria In@mary, Newcastle upon m WK.1
NEI 4LP
1. Introduction Prior to the mid-l 970s the only way of achieving a tan from an artificial source was to use a sunlamp. This was invariably an unfiltered medium or high pressure mercury arc lamp which emitted a broad spectrum of optical radiation from WC (200-290 nm) through to visible and IR radiation. Because of the high WC and WB (290-320 nm) emission, exposure times were short, typically a few minutes. These lamps were inefficient in tanning and it was not uncommon for overexposure to occur resulting in acute eye damage or skin erythema and blistering. Following the development of WA (320400 run) fluorescent lamps it became feasible to induce a tan with WA radiation. In the late 1970s and early 1980s it was suggested that a tan induced by WA was safer than that induced by WB. The tanning industry was quick to seize on this perceived benefit of WA and, as a consequence, WA lamps with minimal or no WI3 content were promoted. Whilst we do not condone tanning, we present arguments which indicate that those people who do wish to tan with arti.flcial sources may be better advised to use lamps in which the WB component, rather than the WA component, contributes the major fraction towards tanning. We consider four different types of lamp and discuss the biological and clinical consequences of tanning with lamps in which either WA or WI3 is the dominant wave band.
2. Lamp characteristics The lamps considered are a medium pressure mercury lamp, a type I WA lamp (e.g. Philips TL09), a type II WA lamp (e.g. Philips TLlO, Mutzhas WASUN) and a ‘simulated sunlight’ lamp. The latter lamp is one in which the ratio of WA to WI3 is similar to that in terrestrial sunlight and in which the W irradiance is such that the time required to achieve a minimal erythema is comparable with sunbathing in summer sunshine at mid-latitudes, i.e. +Author to whom correspondence
should be addressed.
220
NJZWSAND VIEWS
TABLE 1 Characteristics of different UV lamps used for tanning Lamp
Mercury arc sunlamp Simulated sunlight lamp Type I UVA lamp Type II UVA lamp
Radiation emission (%) 1 UVA UVB UVC
UVA
UVJ3
UVC
40 95 99 > 99.9
0 20 60 z-90
35 80 40
