觀點：重新思考北臺灣城市的降溫策略：白色屋頂、反射光與健康之間的平衡
Viewpoint:Rethinking Northern Taiwan’s Heat Relief: White Roofs, Reflected Light, and Health Balance
觀點：重新思考北臺灣城市的降溫策略：白色屋頂、反射光與健康之間的平衡
Original title: A push to cool Australian cities may inadvertently increase our skin cancer risk, unless we act, by Hugh Stanford & Joe Hurley, The Conversation
原文標題：推動為澳洲城市降溫的行動，若不採取對應措施，可能在無意間提高我們罹患皮膚癌的風險，原文作者：Hugh Stanford 與 Joe Hurley，載於《The Conversation》
Summary
原文摘要
Australia is a land of punishing sunshine, driving officials to seek cooler cities by lightening roofs and pavements.
澳洲日照強烈，官方因而致力於透過淺化屋頂與路面來打造更涼爽的城市。
While these “cool city” measures reduce heat absorption, they also risk bouncing more ultraviolet rays onto exposed skin.
然而，這些「涼爽城市」措施雖能減少熱量吸收，卻也可能將更多紫外線反射到裸露的皮膚上。
By brightening our built environment, we may unwittingly boost UV reflections in places where people assume they are safe, worsening the nation’s already high skin cancer rates.
透過使建築環境變得更明亮，我們可能在不知不覺中增加人們以為安全地帶的紫外線反射量，進一步惡化本已居高不下的皮膚癌發病率。
Urban heat islands—where asphalt, concrete, and dark rooftops store and radiate warmth—make daily life uncomfortable.
都市熱島效應，源於柏油、混凝土以及深色屋頂所儲存並釋放的熱量，導致日常生活不適。
Painting roofs white, planting shade trees, and adopting reflective materials promise relief: they cut energy bills, lower street temperatures, and offer respite from scorching noon sun.
刷白屋頂、種植遮蔭樹，以及採用反射性材料皆可帶來改善：它們能降低能源成本、降低街道溫度，並在炙熱的正午陽光下提供片刻清涼。
Yet this strategy relies on reflecting sunlight away, which inadvertently scatters harmful UV rays across footpaths, playgrounds, and other public spaces.
然而，這類策略依賴反射陽光，無意間也將有害的紫外線散射至人行道、遊樂場與其他公共空間。
People standing under partial shade or strolling near light-coloured walls could still catch UV exposure from unexpected angles. Australia’s struggle with skin cancer is no minor concern.
處於部分陰影下或走在淺色牆面旁的人，仍可能從意想不到的角度受到紫外線照射。澳洲在皮膚癌防治上的挑戰絕非小事。
The climate, combined with widespread outdoor activities and fair-skinned populations, results in some of the world’s highest melanoma rates.
氣候條件、普遍的戶外活動，再加上膚色較淺的人口組成，使得澳洲的黑色素瘤發病率居全球前列。
Past slip-slop-slap campaigns promoted sunscreen, hats, and protective clothing, but new reflective surfaces introduce another layer of risk.
先前的「Slip-Slop-Slap」活動宣導防曬乳、帽子與防護衣物，但新的高反射性表面又增加了一重風險。
According to emerging studies, reflected light from bright pavement or white roofs adds to direct sunlight, amplifying the danger for pedestrians—especially children—who often neglect sun-smart habits.
根據新興研究，亮色路面或白色屋頂反射的光線，將與直接照射的陽光相疊，加劇對行人的危害，尤其是那些常忽略防曬習慣的兒童。
How then can officials, engineers, and health experts find a balanced path? One approach is selecting which surfaces to lighten, focusing on rooftops that sit far above the reach of passers-by, rather than big pavements at ground level.
那麼，政府官員、工程師與衛生專家該如何找到平衡之道呢？其中一種作法，是精選需淺化的表面，將重點放在遠離行人高度的屋頂，而非行走範圍廣大的地面路面。
Rooftops do not bounce UV rays into people’s faces and can safely reflect much of the sun’s energy back into the atmosphere. By contrast, wide expanses of reflective concrete can turn sidewalks into sources of indirect UV exposure.
屋頂不會將紫外線直接反射到人臉上，因而能安全地將大部分太陽能量反射回大氣層。相較之下，大面積的高反射混凝土路面可能將人行道變成間接紫外線的來源。
Another tactic involves planting more street trees, installing shade sails, and positioning awnings to prevent reflections from hitting sensitive areas where people linger. Technological advances may help.
另一種策略則是植更多街樹、裝設遮陽帆布，以及在易停留區域設置遮雨棚，以防止反射光照射到敏感地帶。技術上的進步或許能提供助益。
Researchers are exploring coatings that repel infrared heat (the part most responsible for hot surfaces) without bouncing too many ultraviolet rays.
研究人員正積極開發一種能排斥紅外線熱能（最容易造成表面升溫的部分），卻不會反射過多紫外線的塗料。
Though not yet widespread, these coatings could let cities stay cooler without increasing skin cancer risks. Policymakers must also ensure that education campaigns keep pace with changes to urban design.
雖然尚未普及，這些塗料有望讓城市降溫的同時，不再推升皮膚癌風險。決策者也必須確保，公共教育能與城市設計的改變同步推進。
Many people wrongly assume that if the temperature is mild or they are not in direct sunlight, they face less UV danger. In reality, reflection can strike at any angle, including from light-coloured pavements or building walls.
許多人誤以為氣溫不高或未受到直射陽光，就代表紫外線風險降低。事實上，反射光可從任何角度襲來，包括淺色路面或建築牆面。
Above all, a careful balance is needed. Australians cannot live with endless sweltering streets, nor should they be forced to accept higher cancer threats in the name of “cool city” measures.
最重要的是，必須審慎拿捏各方平衡。澳洲民眾無法在炎熱難耐的街道中度日，也不該被迫接受以「涼爽城市」之名而帶來的更高癌症風險。
Through coordinated planning among engineers, designers, and health officials, along with steady public education, it is possible to diminish urban heat without exposing citizens to harmful UV reflections.
透過工程師、設計師與衛生機構的協同規劃，並配合持續的公共教育，確有機會在降低都市熱度的同時，避免讓市民暴露在有害紫外線反射下。
The goal is to create cities that are liveable, energy-efficient, and mindful of their invisible dangers, so that in seeking relief from the sun’s fierce heat, we do not invite an even sharper threat through reflected light.
目標在於打造宜居且具能源效率的城市，同時重視那些潛藏的危害，避免在努力趨避烈日高溫的過程中，反而讓反射光帶來更嚴峻的威脅。
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Rethinking Northern Taiwan’s Heat Relief: White Roofs, Reflected Light, and Health Balance
重新思考北臺灣城市的降溫策略：白色屋頂、反射光與健康之間的平衡
Northern Taiwan, with its dense metropolises and subtropical climate, spends much of the year under a relentless sun.
北臺灣都市密集、屬於亞熱帶氣候，大部分時間都在炙熱的陽光下度過。
Each summer, urban dwellers endure the “heat island” effect, in which concrete and asphalt trap warmth and keep temperatures elevated well into the evening.
每到夏季，都市居民都要忍受「熱島效應」的折磨，因為水泥與柏油持續吸熱，讓氣溫直到夜晚仍居高不下。
Crowded streets, towering high-rises, and heavy traffic intensify this sweltering reality. Unsurprisingly, officials and planners are determined to cool their cities.
擁擠的街道、高聳的建築與繁重的車潮更加劇了這炎熱的情況。毫不意外地，政府與都市規劃者都下定決心要為城市降溫。
Yet recent insights from Australia warn of an unforeseen hazard: while brightening roofs and pavements may reduce heat absorption, the added reflectivity can scatter ultraviolet (UV) rays, increasing the risk of skin damage.
然而，來自澳洲的最新觀察卻警示了一項意料之外的隱憂：雖然透亮屋頂與路面能降低熱量吸收，但其增強的反射度可能將紫外線（UV）四處散射，提升皮膚受損風險。
If city-cooling strategies in Northern Taiwan disregard this risk, they may resolve one predicament only to create another.
若北臺灣的城市降溫策略忽略了這項風險，可能在解決一個問題的同時，又製造出另一個難題。
A measured approach—combining ground-level shading, roof greening, and prudent material selection—stands as the most balanced way forward.
因此，結合地面遮蔭、屋頂綠化與謹慎的材料選擇，才是邁向均衡解方的最佳途徑。
Ground-Level Shading and the Threat of UV Reflection
地面遮蔭與紫外線反射的潛在威脅
City-cooling proposals often focus on roadways and sidewalks.
城市降溫計畫通常將焦點放在道路與人行道上。
By painting them lighter or installing reflective coatings, planners hope to bounce sunlight away before it can bake the surface. Lower street temperatures keep pedestrians more comfortable and reduce cooling costs.
透過將路面漆成較淺色，或使用反射性塗料，規劃者希望在陽光灼熱地表之前就先將其反射出去。較低的街道溫度能讓行人更舒適，也能減少空調成本。
But UV rays make little distinction between scorching tarmac and pale pavement. When they hit bright surfaces, they can ricochet unpredictably, exposing unsuspecting passers-by.
然而，紫外線並不會分辨灼熱的柏油與淺色路面；當它們照射到明亮表面時，會以不可預測的方式反射，讓毫無防備的路人暴露在紫外線下。
Northern Taiwan’s urban landscapes are cramped: narrow alleys and tall buildings can create an intricate web of reflections, sending stray beams into corners that would otherwise be in shadow.
北臺灣的都市環境空間狹窄：巷弄狹小、建築物高聳，可能形成錯綜複雜的反射網絡，將零散的光束引導至原本處於陰影的角落。
Shaded walkways, covered arcades, and tree-lined streets are thus crucial. They grant pedestrians respite from the blazing sun and block or diffuse harmful UV reflections.
因此，設置遮蔭走道、騎樓以及綠蔭街道，便顯得相當重要。這些設施能讓行人遠離烈日，並阻擋或分散有害的紫外線反射。
Strategic planting is especially helpful: street trees moderate temperature through evapotranspiration and also reduce UV scatter, softening the risk to those who linger outdoors.
有策略地種植綠蔭更是有助益：街道樹木透過蒸發散作用調節溫度，同時也能減少紫外線的散射，降低室外逗留人群的風險。
Rooftop Measures: Reflective Coatings vs. Greenery
屋頂降溫策略：反射塗層與綠化之比較
Above the streets, rooftops form a vast canvas for city-cooling projects.
在街道之上，屋頂就像一幅供城市降溫計畫使用的巨大畫布。
Across Taiwan, countless concrete rooftops absorb large amounts of heat, forcing building occupants to ramp up air-conditioning.
在臺灣各地，無數水泥屋頂吸收大量熱能，迫使建築使用者必須提高冷氣用量。
Proponents of “cool roofs” urge reflective membranes or lighter-coloured tiles, aiming to channel heat away from buildings. In principle, these methods help cut energy bills and mitigate the heat island effect.
主張「涼爽屋頂」的人鼓勵使用反射膜或淺色磁磚，希望能將建築表面的熱量反射出去。理論上，這些作法確實能降低能源開支並舒緩熱島效應。
Yet officials must be aware that highly reflective rooftops may direct UV rays onto neighbouring properties. Where elevations vary sharply—common in hilly Northern Taiwan—light from one rooftop could bounce down into balconies or street-level windows.
然而，政府單位必須留意到，高度反射的屋頂可能將紫外線導向鄰近建物。在地勢起伏較大的北臺灣，來自某個屋頂的反射光線可能會反射到鄰近的陽臺或一樓窗戶。
Green roofs present an appealing alternative. By planting vegetation atop buildings, we can filter out a good deal of solar energy without sending large amounts of UV light into the air.
綠屋頂則提供了另一種具吸引力的選擇。透過在建物頂層種植植栽，我們能過濾掉大量太陽能量，而不會將大量紫外線反射到空中。
Plant canopies and soil layers absorb heat, enhance local biodiversity, and even improve air quality.
植物覆蓋與土壤層能吸收熱量，促進在地生物多樣性，甚至改善空氣品質。
Nevertheless, green rooftops demand thorough upkeep: they require appropriate drainage, irrigation, and structural checks to handle Taiwan’s frequent downpours and typhoons. Not every building can support a layer of soil and vegetation.
然而，綠屋頂也需要完善的維護：必須有適當的排水、灌溉與結構檢查，才能應對臺灣頻繁的豪雨與颱風。並非所有建築都能承受土壤與植栽的重量。
In older neighbourhoods, structures may not be strong enough to bear the weight. Even so, policymakers should encourage green roof adoption where it is feasible, offering subsidies or tax incentives.
在較老舊的社區，建築結構可能不足以支撐這種負荷。即便如此，決策者仍應在可行的地區推廣綠屋頂，並提供補助或稅務優惠。
If widely implemented, this practice could greatly reduce rooftop heat absorption and lessen reflected UV.
若能廣泛推行，綠屋頂將大幅降低屋頂吸收熱量與反射紫外線的程度。
Selecting Materials and Colours Wisely
謹慎選擇材料與顏色
Cities in warmer climates tend to opt for light or white surfaces in their roofs and pavements. These reflect sunlight well, lowering ambient temperatures.
在較溫暖的氣候地區，城市往往會選擇淺色或白色的屋頂與路面。這些表面能有效反射陽光，進而降低周圍的溫度。
But if the reflective index is too high, more UV radiation bounces around, potentially harming people. One solution is to use materials with advanced coatings designed to reflect infrared (the key contributor to heat) without scattering excessive UV.
然而，若反射率過高，更多紫外線將被彈射到各處，可能傷害到民眾。其中一個解方是使用先進塗料的材料，這些塗料主要反射造成熱量的紅外線，同時避免反射過多紫外線。
Though still in development, these coatings might allow Northern Taiwan’s buildings to stay cooler while minimising glare. Similarly, gentler hues—light grey, pale green, or other muted shades—can help strike a middle ground.
儘管仍在開發中，這些塗層可能會讓台灣北部的建築物保持涼爽，同時最大限度地減少眩光。同樣，柔和的色調——淺灰色、淺綠色或其他柔和的色調——可以幫助達成中間立場。
Such surfaces reflect part of the solar spectrum while preventing intense UV scatter. Finishes that are matte or textured may disperse reflected light more softly.
這類表面能反射部分太陽光譜，同時避免強烈的紫外線散射。啞光或具紋理的表面處理則能更柔和地分散反射光。
Still, Taiwan’s humidity and monsoon-like rains complicate these choices: some coatings may peel or lose effectiveness in constant wetness. That is why careful testing and maintenance—particularly on rooftops—are essential.
然而，臺灣的高濕度與季風型豪雨讓選材更為複雜：某些塗料可能在潮濕環境中剝落或效用下降。這也是為何要在使用前謹慎測試並定期維護，尤其是屋頂部位，至關重要。
Over time, materials degrade, altering their reflective properties and requiring periodic updates.
隨著時間推移，材料會老化，其反射特性也會改變，因此需要定期更換或升級。
Education and Public Awareness
教育與公眾意識
Even with the most sophisticated materials, the public must stay alert to the dangers of indirect UV. If cooler pavements or rooftops lead people to assume the sunlight is harmless, they may forego hats or sunscreen.
即使擁有最先進的材料，大眾仍需保持警覺，避免忽略間接紫外線的危害。若較涼爽的路面或屋頂讓人誤以為陽光無害，他們可能就不再使用帽子或防曬用品。
In truth, scattered UV rays remain potent, especially in bright midday conditions. In Northern Taiwan, cloud cover can be misleading, as the sun’s rays can slip through gaps and bounce off lighter surfaces.
事實上，散射的紫外線依舊威力不減，特別是在正午強光下。在北臺灣，雲層覆蓋常讓人麻痺，太陽光能穿透雲縫並從淺色表面反射。
An integrated outreach campaign could remind residents that city-cooling policies do not neutralise UV exposure. Rather, simple precautions—wide-brimmed hats, parasols, long-sleeved clothing—remain as relevant as ever.
一項整合性的宣導計畫可以提醒居民，城市降溫政策並不代表能消除紫外線的威脅。事實上，簡單的防護措施，如寬邊帽、陽傘與長袖衣物，依舊不可或缺。
Schools play an invaluable role here. By teaching children about the sun’s angles and the science of reflection, we instil lifelong protective habits.
學校在此扮演不可或缺的角色，透過教授孩童太陽角度與反射科學，能為他們建立終身受用的防護習慣。
Shopkeepers, too, could hang advisories or offer shaded seating, fostering an environment of shared responsibility. The more everyday citizens understand about indirect sunlight, the less likely they are to be caught off guard by reflected beams.
店家也可以張貼提醒或提供遮蔭座位，打造一個共擔責任的環境。一般市民對間接陽光瞭解越多，就越不會被反射光束所打個措手不及。
Balancing Comfort, Environment, and Health
在舒適度、環境與健康之間取得平衡
While the impetus to cool Northern Taiwan’s cities is vital—especially given intensifying summers—urban design rarely offers an absolute panacea.
儘管為北臺灣城市降溫至關重要，特別是在夏季日益嚴峻的情況下，但都市設計很難提供一勞永逸的萬靈藥。
Improved cooling can create new challenges if applied without foresight. Lighter streets, for instance, could reflect enough UV to cause an uptick in skin complaints, particularly among delivery workers, street vendors, or seniors unable to limit their outdoor time.
若缺乏前瞻規劃，降溫手段也可能引發新的問題。例如，淺色路面可能反射足以造成皮膚問題的紫外線，對外送員、街頭攤販或無法減少戶外活動的銀髮族尤其有害。
If rooftop measures fail to consider reflectivity angles, neighbouring buildings might face additional glare, prompting complaints or health concerns. Green roofs, though less reflective, demand more investment to maintain.
若屋頂降溫措施忽略了反射角度，鄰近建物可能面臨額外的眩光，衍生民怨或健康疑慮。雖然綠屋頂反射度較低，但需要更多的後續投資與維護。
They also hinge on building owners’ willingness and ability to sustain a rooftop garden. Advanced coatings promise an elegant compromise but must be tested in the field, accounting for Taiwan’s high humidity, typhoon patterns, and potential wear-and-tear.
這也取決於建物所有人是否願意且有能力維持屋頂花園。先進塗料雖能提供看似完美的折衷方案，但仍需經實地測試，考量臺灣的高濕度、颱風型態及可能的磨損。
Meanwhile, tree planting programmes must navigate congested sidewalks, underground utilities, and heavy foot traffic. Each measure thus requires a thoughtful application, shaped by expert input from architects, environmental scientists, and healthcare professionals.
同時，街樹種植計畫還需面對擁擠的人行道、地下管線與龐大的人潮流量。因此，每項作法都須經過審慎評估，並結合建築師、環境科學家與醫療專業人士的意見。
Moving Forward With Caution and Resolve
謹慎而堅定地前行
A robust approach might begin with pilot programmes on select buildings or neighbourhood blocks.
一個堅實的作法可以從幾棟建築或特定街區的試點計畫開始。
Local councils could monitor temperature drops, changes in energy consumption, and shifts in UV exposure. If problems arise—like unanticipated glare or peeling surfaces—planners can adjust the scheme before rolling it out citywide.
地方政府可追蹤溫度下降幅度、能源消耗的變化，以及紫外線曝露程度的轉變。若出現問題，例如意外的眩光或塗層剝落，規劃者可在全面推行前先行調整。
Building codes, too, could be revised in stages, mandating certain reflectivity limits or green-roof coverage for new developments.
也可以逐步修訂建築法規，規定新開發案須符合特定反射度或綠屋頂覆蓋率。
Where old structures are renovated, property owners might be given incentives or rebates to adopt moderate-reflectivity roofs or partial roof gardens. Throughout this process, local authorities must keep the public informed.
對於老舊建物的翻修，則可提供誘因或補助，鼓勵業主採用中度反射性屋頂或部分綠化的屋頂花園。在此過程中，地方政府務必讓民眾持續掌握資訊。
Declaring that reflective streets and bright roofs “solve” the heat problem could lull citizens into ignoring UV risks. Instead, the narrative should stress trade-offs: to ease urban heat, we may use materials and designs that alter how sunlight behaves.
宣稱反光街道和明亮的屋頂「解決」了高溫問題可能會讓公民忽視紫外線風險。相反，敘述應該強調權衡：為了緩解城市熱量，我們可以使用改變陽光行為的材料和設計。
Accordingly, there is a renewed need for shading, protective clothing, and surveillance of unexpected glare.
因此，更需重視遮蔭、防護衣物，以及對意外強光的防範。
City-cooling measures also tie into broader sustainability goals. Cutting down on heat retention lowers energy demand, thus reducing greenhouse gas emissions.
城市降溫措施也與更宏觀的永續目標相互連結。減少熱能積聚即可降低能源需求，也能減少溫室氣體排放。
Green roofs, beyond moderating temperature, bolster biodiversity and promote mental well-being. Shaded sidewalks make walking and cycling more appealing, shrinking both traffic and air pollution.
綠屋頂除了降溫外，還能增進生物多樣性並提升心理健康。有遮蔭的人行道令步行與騎車更具吸引力，進一步減少交通量與空氣汙染。
In essence, Northern Taiwan’s leaders face a choice: either address the heat island effect in isolation or tackle it through a holistic strategy that weighs comfort, ecology, and health side by side.
總的來說，北臺灣的領導者正面臨抉擇：要麼只孤立地處理熱島效應，要麼透過綜合策略，將舒適度、生態與健康並重考量。
Conclusion
結論
As Northern Taiwan races to cope with rising temperatures, it must not lose sight of the hidden costs of reflectivity.
當北臺灣全力因應逐年攀升的氣溫時，絕不能忽略高反射度可能帶來的隱藏代價。
Lessons from Australia illustrate that a single-minded quest for cooler streets and rooftops can pave the way for heightened UV exposure, impacting people who rely on outdoor spaces the most.
從澳洲的案例可看出，若只一味追求降溫的街道與屋頂，反而可能大幅增加紫外線曝露，尤其衝擊那些經常在戶外活動的人。
Fortunately, a balanced approach—combining moderate reflectivity, rooftop greenery, shaded walkways, and public education—can bring relief without sowing fresh hazards.
所幸，結合適度反射、屋頂綠化、遮蔭走道與公眾教育的綜合策略，能在降低高溫的同時避免新危害的產生。
Through thorough testing, collaborative policymaking, and widespread awareness campaigns, the region can reimagine its cityscape as both cooler and safer.
透過完整的測試、協同的決策制定以及廣泛的宣導計畫，北臺灣能在城市面貌上重新定位，讓環境同時更涼爽也更安全。
In that way, Northern Taiwan will prove that clever urban design does not have to pick between comfort and health: each can thrive, provided we are vigilant about the forces we unleash in the name of progress.
如此一來，北臺灣將展現出聰明的城市設計無需在舒適與健康之間二擇一；只要我們對以進步之名所帶來的種種效應保持警覺，兩者皆能兼得。
