British Journal of Dermatotogy {19S2} 127, 10-12.
Sun protection with hats B.L.DIFFEY AND J.CHEESEMAN Regiona! Medical Physics Departmenl. Dryburn Hospital. Durham DHl 5TW, U.K. Accepted for publication 4 February 1992
Summary
The degree of sun protection provided by various styles of hat at different anatomical sites on the head was measured using model headfonrns and ultraviolet-sensitive film badges. It was found that hats with a small brim, such as the flat cap favoured by elderly male photosensitive patients, provided negligible protection at all sites apart from the vertex and forehead. Peaked baseball-style caps offer good protection to the nose but are relatively ineffective at other sites on the face. Hats with a wide ( > 7 ' 5 cm) brim are necessary in order to provide reasonable protection factors {> 3) around the nose and cheeks.
Measures which can be taken to protect the skin from excessive solar ultraviolet radiation (UVR) exposure are avoiding direct sunlight around the middle of the day. making use of shade, applying topical sunscreens and wearing suitable clothing, including hats.' In photosensitive patients, the face is commonly affected" and general advice on management often includes encouraging patients to wear a hat. Yet despite the conventional wisdom that wearing a hat is a useful photoprotective measure, there are few data on the quantitative benefits to be expected. Previous studies''•'' have shown that wearing a brimmed hat reduces exposure to the face, but little information has been provided with regard to protection at different sites on the head. The purpose of this study was to measure protection achieved at various anatomical sites on the head and neck from wearing different styles of hat. The sites chosen were the forehead, nose, cheeks, chin and back of neck because, in photosensitive patients, it is these areas of skin that are particularly affected.^
ture of 16x 12 mm. These were attached to six sites (forehead, nose, both cheeks, chin and back of neck) on a PVC head form (model THl 170: Banbury Postiche Ltd. Banhury. U.K.) by means of 'Blu-Tack'. Six heads were mounted 45 cm apart along a rod 2-4 m in length. Different hats were placed on five of the heads and one head left uncovered. An additional tilm badge was placed on the vertex of the uncovered head. The assembly was placed outdoors and rotated at 0-4 rev,/min for approximately 2-3 h during either a morning or afternoon (Fig. 1). Because the change of solar altitude was negligible during one revolution of the heads, their rotation at constant velocity may be regarded as equivalent to the random motion of a human subject outdoors. Measurements were made on six separate occasions on 20-23 August 1991 at Durham. England (latitude 55° N). During this period the weather was mainly sunny and
Methods ultraviolet radiation exposure was measured using the polymer film polysulphone.^ The film readily degrades when exposed outdoors, and as a measure of the degree of solar IIVR exposure the change in optical absorbance of the polysulphone film was measured at 3 30 nm. Badges were constructed by mounting the film in cardboard holders 30-mm square with a central aper-
Correspondence: Dr B.L.Diffey 10
k
Figure I. "1 he heads rotating outd
SUN PROTECTION WITH HATS
11
Table 1. Soiar UVR exposure at various sites on head and neck
Percentage of solar exposure relative to unprotected head Hat position (FiK. 2)
3 3 3 3 3 3 3 4 4 4
Hat description
Hat classification*
1 2 3 4 5 6 7 1 2 3 4
White sun-hat with targe floppy brim Brown tweed Bat cap Red cotton sun-hat Straw boater Blue hat with large floppy brim Beige straw hat with large floppy brim Brown corduroy flat cap Green hat with lar^e floppy brim Airline pilot peaked cap Green plastic visor (no crown) Grey cotton baseball cap Denim cotton peaked cap Checked deerstalker cap Checked flat cap White cotton baseball cap Red baseball cap with netting on crown Trilby hat Russian fur hat Ladies pink hat Tartan trilby hat Straw sun-hat Straw boater Blue denim sun-hat Brown trilby hat Silk headscarf White cotton cricketer's hat Red cap with ear flaps Straw sun-hal with large brim
L S M
6 7 1
2
4 4 4
3 4 5 6 7 1 2 3 4 5 6
4
7
M L L S
L P
P P P
P S P P M S M M L L
Forehead 5 7 2 I 2 7 4 3 0 6
1 3 0 4 1 0 3 24 45 5 6
IS
M M — L P
77 4 42
L
4
b
24
Nose 17 70 32 20 9
20 67 14 6 8 65 45 11 48 23 17 69 93 84 59
28 68 4 81 95 2 45 7
Uft cheek
Right cheek
29 79 44 54 10 54 97 27 81 45 114 91 62 100 54 60 88 105 77 81 64 86 6 108 115 16 68 44
39 107 97 50 13 53 99 45 84
49 106 82 78 133 85 53 90 132 100 69 67 83 S 124 126 0 61 32
Chin 123 140 120 120 41 97 85 74 87 72 92 96 125 128 103 106 94 109 103 117 126 102 80 109 97 78 86 63
Back of neck 8 105 29 92 5 IJI
1 1 1 1 I 1 1 2 2 2 2 2 2 2
Column
Ol
Row
85 10 90 94 72 89 44 76 69 121 75 50 51 68 56 73 37 66 0 16 J8 93
'Hat classification: S. small brim ( 7 5 cmj; P. peaked cap.
the solar altitudes ranged from 31 ° to 47°. A total of 28 hats were used, including a ladies headscarf and a plastic sun visor with no crown (Fig. 2).
Figure 2. The 28 hats worn In the study.
Results The ultraviolet exposure recorded by a given film badge was expressed as a percentage of that recorded at the same anatomical site on the uncovered head during the same period of exposure. This enabled an estimate to be made of the protection at a given site achieved by wearing a particular hat. These results are shown in Table 1. It can be seen that in some cases the percentage of solar UVR recorded at a site was higher than that received at the corresponding site on the uncovered head. We attribute this to differences in the orientation of the film badges at the same site between heads. By comparing the relative doses recorded on uncovered heads on the six separate occasions it was possible to estimate the uncertainty that differences in orientation were likely to contribute. These data are summarized in
12
li.L.DIFFEY AND |.CHKKSKMAN
Table 2. Stiliir (IVR cxpostiri.' on dilTt'rt'nl .silfs o!" iiruiivtTcd rcliitive It) tluit roairdiHl tm vertt'x on eiifh of six s
k" 5. Siimriiiiry olsuii-protcrlinn liiilorsitl \ aridiissiU'sen neck pnivkk'il !iy ditTtTi'iil lypi's of liiil
1 ypkal sun-protei'tUm factor
Relative exposure on occasion 2
Site
5
4
S
6
Mean ± t SD Style of hat
Vertex Forehfiid Nose IHt dieek Rinhl chwk Chin Backofnetk
100 44 St 54 25 21 50
100 5(1 4S 25 25 2=i 52
Kill 40 S7 5(t 2S !0 ift
100 iS SO 2S 21 2^) il
too 48 Si) 29 !i 51 29
HIO 41 S7 52 51 2h JS
too 41 i S S4±4 29*4 2f) + 4 27±4 i2± J
2 ;md yield iin ovtTJill focBUicnl ol' vjirUitioii of
Small brim ( < 2 S a n ) Medium brim (2-S-7-T a n ) l,iirge hrim I ',• 7 S a n ) I't'iiked c'iip
Porehead I S -^20 >20 -•20
Nose Cheek
Chin
tlHck of neck
1-2
other sites on the head and neck. For people outdoors in sunny climates, such as Australia, a hat with at Icasl a 7S-cm brim is necessary to provide reasonable protection arcuind the nose and checks, those sites on which non-melanoma skin cancers commonly occur.
Discussion The hats illustrated in Figure 2 can be classified into one of four categories: small brim ( 7 - 5 cm); and pcukcd cap. The •protection factor' provided at a given site by a piirticiilar style of hat is equal to the reciprocal of the fraction of UVK exposure recorded relalive to the unprotected head. For hats in each of the four categories the data in Table 1 were reduced by calculating the geometric mean protection factor at each site to give the summary in Table i. It may be seen that all types of headgear provide good protection to the forehead. Hats with little or no brim, as may be favoured by elderly mate photosensitive patients, provide negligible protection at
References 1 Marks R. Prevention of skin cancer: bein({ sunsniart in i h e I ^J'iOs. Il)ermalohtiical Tri'iitment 1 9 9 0 : t : 2 7 t - 4 . 2 tTain-Bt'll W. i'liumeims I'hoHihiolofUi. Oxford: Oxford tiniversity Press. I 9 S S : 12. 5 Kosenlhal FS. Sitfriin M. Tuylor HR. riit'otiilHr Jose of ultra viok'l radiation from sunlight exposure, t'lwux-lwni I'hotobio! I9H5: 4 2 : lf)J-7t. 4 tlies P. Roy C. hllliott C The iiiuiloiiiiail distribution ofsoliir IVK with emphasis on the i-yv. I'nHfciliims of the 7th hitenmtwml i'lmircss of the liilrnunhtHil RiulUitiim Protection Assotiatioti. Sydney: Pergamon Press 14S8: 541-4. 5 DifTey BL. l!ltr>ivioiet riidiiKinn dosimetry with polysulphoiu' lilm. In: Riiiliiilicn Mi-n.'^urnm-iit iit I'hotohiolofin iDilTey HI., cdi. (.inuinn: Press. iy«9; 1 iS-S9.
Sun protection with hats B.L.DIFFEY AND J.CHEESEMAN Regiona! Medical Physics Departmenl. Dryburn Hospital. Durham DHl 5TW, U.K. Accepted for publication 4 February 1992
Summary
The degree of sun protection provided by various styles of hat at different anatomical sites on the head was measured using model headfonrns and ultraviolet-sensitive film badges. It was found that hats with a small brim, such as the flat cap favoured by elderly male photosensitive patients, provided negligible protection at all sites apart from the vertex and forehead. Peaked baseball-style caps offer good protection to the nose but are relatively ineffective at other sites on the face. Hats with a wide ( > 7 ' 5 cm) brim are necessary in order to provide reasonable protection factors {> 3) around the nose and cheeks.
Measures which can be taken to protect the skin from excessive solar ultraviolet radiation (UVR) exposure are avoiding direct sunlight around the middle of the day. making use of shade, applying topical sunscreens and wearing suitable clothing, including hats.' In photosensitive patients, the face is commonly affected" and general advice on management often includes encouraging patients to wear a hat. Yet despite the conventional wisdom that wearing a hat is a useful photoprotective measure, there are few data on the quantitative benefits to be expected. Previous studies''•'' have shown that wearing a brimmed hat reduces exposure to the face, but little information has been provided with regard to protection at different sites on the head. The purpose of this study was to measure protection achieved at various anatomical sites on the head and neck from wearing different styles of hat. The sites chosen were the forehead, nose, cheeks, chin and back of neck because, in photosensitive patients, it is these areas of skin that are particularly affected.^
ture of 16x 12 mm. These were attached to six sites (forehead, nose, both cheeks, chin and back of neck) on a PVC head form (model THl 170: Banbury Postiche Ltd. Banhury. U.K.) by means of 'Blu-Tack'. Six heads were mounted 45 cm apart along a rod 2-4 m in length. Different hats were placed on five of the heads and one head left uncovered. An additional tilm badge was placed on the vertex of the uncovered head. The assembly was placed outdoors and rotated at 0-4 rev,/min for approximately 2-3 h during either a morning or afternoon (Fig. 1). Because the change of solar altitude was negligible during one revolution of the heads, their rotation at constant velocity may be regarded as equivalent to the random motion of a human subject outdoors. Measurements were made on six separate occasions on 20-23 August 1991 at Durham. England (latitude 55° N). During this period the weather was mainly sunny and
Methods ultraviolet radiation exposure was measured using the polymer film polysulphone.^ The film readily degrades when exposed outdoors, and as a measure of the degree of solar IIVR exposure the change in optical absorbance of the polysulphone film was measured at 3 30 nm. Badges were constructed by mounting the film in cardboard holders 30-mm square with a central aper-
Correspondence: Dr B.L.Diffey 10
k
Figure I. "1 he heads rotating outd
SUN PROTECTION WITH HATS
11
Table 1. Soiar UVR exposure at various sites on head and neck
Percentage of solar exposure relative to unprotected head Hat position (FiK. 2)
3 3 3 3 3 3 3 4 4 4
Hat description
Hat classification*
1 2 3 4 5 6 7 1 2 3 4
White sun-hat with targe floppy brim Brown tweed Bat cap Red cotton sun-hat Straw boater Blue hat with large floppy brim Beige straw hat with large floppy brim Brown corduroy flat cap Green hat with lar^e floppy brim Airline pilot peaked cap Green plastic visor (no crown) Grey cotton baseball cap Denim cotton peaked cap Checked deerstalker cap Checked flat cap White cotton baseball cap Red baseball cap with netting on crown Trilby hat Russian fur hat Ladies pink hat Tartan trilby hat Straw sun-hat Straw boater Blue denim sun-hat Brown trilby hat Silk headscarf White cotton cricketer's hat Red cap with ear flaps Straw sun-hal with large brim
L S M
6 7 1
2
4 4 4
3 4 5 6 7 1 2 3 4 5 6
4
7
M L L S
L P
P P P
P S P P M S M M L L
Forehead 5 7 2 I 2 7 4 3 0 6
1 3 0 4 1 0 3 24 45 5 6
IS
M M — L P
77 4 42
L
4
b
24
Nose 17 70 32 20 9
20 67 14 6 8 65 45 11 48 23 17 69 93 84 59
28 68 4 81 95 2 45 7
Uft cheek
Right cheek
29 79 44 54 10 54 97 27 81 45 114 91 62 100 54 60 88 105 77 81 64 86 6 108 115 16 68 44
39 107 97 50 13 53 99 45 84
49 106 82 78 133 85 53 90 132 100 69 67 83 S 124 126 0 61 32
Chin 123 140 120 120 41 97 85 74 87 72 92 96 125 128 103 106 94 109 103 117 126 102 80 109 97 78 86 63
Back of neck 8 105 29 92 5 IJI
1 1 1 1 I 1 1 2 2 2 2 2 2 2
Column
Ol
Row
85 10 90 94 72 89 44 76 69 121 75 50 51 68 56 73 37 66 0 16 J8 93
'Hat classification: S. small brim ( 7 5 cmj; P. peaked cap.
the solar altitudes ranged from 31 ° to 47°. A total of 28 hats were used, including a ladies headscarf and a plastic sun visor with no crown (Fig. 2).
Figure 2. The 28 hats worn In the study.
Results The ultraviolet exposure recorded by a given film badge was expressed as a percentage of that recorded at the same anatomical site on the uncovered head during the same period of exposure. This enabled an estimate to be made of the protection at a given site achieved by wearing a particular hat. These results are shown in Table 1. It can be seen that in some cases the percentage of solar UVR recorded at a site was higher than that received at the corresponding site on the uncovered head. We attribute this to differences in the orientation of the film badges at the same site between heads. By comparing the relative doses recorded on uncovered heads on the six separate occasions it was possible to estimate the uncertainty that differences in orientation were likely to contribute. These data are summarized in
12
li.L.DIFFEY AND |.CHKKSKMAN
Table 2. Stiliir (IVR cxpostiri.' on dilTt'rt'nl .silfs o!" iiruiivtTcd rcliitive It) tluit roairdiHl tm vertt'x on eiifh of six s
k" 5. Siimriiiiry olsuii-protcrlinn liiilorsitl \ aridiissiU'sen neck pnivkk'il !iy ditTtTi'iil lypi's of liiil
1 ypkal sun-protei'tUm factor
Relative exposure on occasion 2
Site
5
4
S
6
Mean ± t SD Style of hat
Vertex Forehfiid Nose IHt dieek Rinhl chwk Chin Backofnetk
100 44 St 54 25 21 50
100 5(1 4S 25 25 2=i 52
Kill 40 S7 5(t 2S !0 ift
100 iS SO 2S 21 2^) il
too 48 Si) 29 !i 51 29
HIO 41 S7 52 51 2h JS
too 41 i S S4±4 29*4 2f) + 4 27±4 i2± J
2 ;md yield iin ovtTJill focBUicnl ol' vjirUitioii of
Small brim ( < 2 S a n ) Medium brim (2-S-7-T a n ) l,iirge hrim I ',• 7 S a n ) I't'iiked c'iip
Porehead I S -^20 >20 -•20
Nose Cheek
Chin
tlHck of neck
1-2
other sites on the head and neck. For people outdoors in sunny climates, such as Australia, a hat with at Icasl a 7S-cm brim is necessary to provide reasonable protection arcuind the nose and checks, those sites on which non-melanoma skin cancers commonly occur.
Discussion The hats illustrated in Figure 2 can be classified into one of four categories: small brim ( 7 - 5 cm); and pcukcd cap. The •protection factor' provided at a given site by a piirticiilar style of hat is equal to the reciprocal of the fraction of UVK exposure recorded relalive to the unprotected head. For hats in each of the four categories the data in Table 1 were reduced by calculating the geometric mean protection factor at each site to give the summary in Table i. It may be seen that all types of headgear provide good protection to the forehead. Hats with little or no brim, as may be favoured by elderly mate photosensitive patients, provide negligible protection at
References 1 Marks R. Prevention of skin cancer: bein({ sunsniart in i h e I ^J'iOs. Il)ermalohtiical Tri'iitment 1 9 9 0 : t : 2 7 t - 4 . 2 tTain-Bt'll W. i'liumeims I'hoHihiolofUi. Oxford: Oxford tiniversity Press. I 9 S S : 12. 5 Kosenlhal FS. Sitfriin M. Tuylor HR. riit'otiilHr Jose of ultra viok'l radiation from sunlight exposure, t'lwux-lwni I'hotobio! I9H5: 4 2 : lf)J-7t. 4 tlies P. Roy C. hllliott C The iiiuiloiiiiail distribution ofsoliir IVK with emphasis on the i-yv. I'nHfciliims of the 7th hitenmtwml i'lmircss of the liilrnunhtHil RiulUitiim Protection Assotiatioti. Sydney: Pergamon Press 14S8: 541-4. 5 DifTey BL. l!ltr>ivioiet riidiiKinn dosimetry with polysulphoiu' lilm. In: Riiiliiilicn Mi-n.'^urnm-iit iit I'hotohiolofin iDilTey HI., cdi. (.inuinn: Press. iy«9; 1 iS-S9.
