| 摘要: | 受大氣臭氧層破壞及溫室效應地表暖化影響，人類遭受日光紫外線輻射及濕熱危害之暴露風險日增，其中又以從事戶外作業勞工較受關注。近年來國民使用防護措施之意識逐步提升，包含使用防曬乳液、防曬衣物、及於戶外活動時尋求遮蔽。本研究利用皮膚生理指標以及主觀熱感知問卷，針對防曬袖套可對自然紫外光曝曬提供之防護效能以及其使用在濕熱地區如我國可能對使用者產生之熱不舒適進行評估。研究所選定之皮膚生理指標包含：皮膚微血流變化量(skin capillary blood flow, SCBF)、經皮水分散失量(transepidermal water loss, TEWL)、皮膚溫度、皮膚濕度、紅斑生成指數(erythema-index, E-index)與黑色素沉澱指數(melanin-index, M-index)；主觀熱舒適感則以美國冷凍空調技師協會Standard 55標準問卷為基礎發展之中文問卷調查。
本研究包括二主要階段。第一階段於人工氣候環境暴露艙內模擬不同環境溫濕度，量化評估室內環境物理因子對皮膚生理指標之影響，以及防曬袖套使用是否改變其影響模式。第二階段於戶外進行日光曝曬實驗。實驗採定期短時間暴露方式，於無日光照射處與日光曝曬處量測各項皮膚生理指標與主觀熱感知變化，以評估因應日光曝曬產生之立即性與累積性皮膚生理與主觀熱舒適反應，以及防曬袖套之使用對上項反應之影響。各階段均建立劑量(環境物理因子)-反應(生理指標)關係，以分析量化防曬袖套使用可降低之健康傷害。
室內暴露艙實驗結果發現：在高環境溫度(34oC)環境使用防曬袖套可抑制手臂皮膚排汗，造成實驗組之TEWL值較控制組為低。比較防曬乳液與防曬袖套之使用者發現，因乳液具有保溼效果且與皮膚緊密接觸，故隨環境溫度升高時使用者之TEWL與皮膚濕度較使用防曬袖套者高。戶外日光曝曬實驗發現：環境物理因子中輻射熱強弱是影響皮膚生理指標反應戶外熱環境變化之重要關鍵；黑球溫度高時對應之熱調節機制主要為皮膚濕度與TEWL變化。在日光紫外線直接曝曬狀況下，當環境溫度為34-36oC時，使用防曬袖套之受試者會因袖套侷限，導致皮膚表面散熱不易，刺激熱調節過度反應，造成皮膚溫度高達40oC。經為期四個月之暴露後發現，使用防曬袖套受試者之皮膚M-index隨累積暴露之紫外線能量增加出現下降，而未使用防曬袖套者則呈現上升趨勢，顯示M-index為反應長期日光紫外線危害之良好生理指標，同時防曬袖套之使用能適度降低皮膚黑色素之生成。
This study was conducted in two successive stages. In the first stage, the influence of environmental temperature and relative humidity, individually or jointly, on human skin physiology was investigated in a controlled environmental chamber. The results between users of sun-protective sleeves and non-users were compared to evaluate changes of physiological properties in response to incremental shift of thermal status in an UV-free environment attributable to sleeve use. In the second stage, sessions of out-of-door experiment were conducted periodically, each simulating a short-term, regular exercise, to evaluate changes in physiological properties and thermal sensation caused by solar UV irradiation in the users of protective sleeves vs. in the non-users. In each session, the subjects were required to stay in two distinct areas for receiving skin physiology measurement and thermal sensation survey, one under direct solar exposure and the other shaded by building. The results were quantified to show both the immediate and cumulative effects of solar UV exposure and the efficacy of sun-protective sleeves. The dose-response relationships between the investigated environmental variables and skin physiological indicators were established in both stages to support a final analysis on the reduction of solar UV health hazard attributed to the use of sun-protective sleeves.
As the results reported by the environmental chamber experiment show, the use of protective sleeves inhibited the formation of water vapor in the form of TEWL increase on the dorsal skin of the left forearm at high environmental temperature (34oC). When the use of sunscreens and of sun-protective sleeves were compared, the sunscreens were found to maintain skin hydration and function as a permeable membrane in intimate contact with the skin, resulting in an elevated TEWL compared to the levels measured on the skin of sleeve users. The findings from the outdoor experiments indicate that the rediant heat was the primary variable controlling the response of skin physiology to the outdoor thermal environment. The change in skin moisture and TEWL was the apparent thermoregulatory mechanism involved in responding to a significant presence of radiant heat in the ambient environment, as expressed in the globe temperature. Under direct sunlight exposure, the air pocket confined within the protective sleeves and in direct contact with the skin became over-heated when the environmental temperature reached 34-36oC, developing a pseudo thermal environment that stimated thermoregulation to over-respond, resulting in an elevated skin temperature of up to 40oC. Following exposure of 4 months, the M-index of the sleeve users’ skin decreased whereas that of the non-users rose, suggesting that M-index was an ideal physiological indicator for observing the long-term effect of solar UV exposure and that the use of sun-protective sleeves adequately reduced melanogenesis due to excess solar UV irradiation. |
