空氣污染讓人鬱悶還讓人笨?大綱
This month, the Indian Medical Association declared a public health emergency in New Delhi because of high levels of air pollution. Schools were shut and emergency traffic restrictions put in place.
11月，印度醫學協會(Indian Medical Association)宣佈由於空氣污染嚴重，新德里進入公共健康緊急狀態。學校停課，緊急交通限制措施出爐。
Air pollution in New Delhi is nearly 30 times the level considered safe by the World Health Organization, causing more damage to the lungs than smoking two packs of cigarettes a day.
新德里的空氣污染程度超出世界衛生組織(WHO)安全上限近30倍，其對肺的損害超過每日吸兩包香菸。
New Delhi is far from alone. Our research into the impact of air pollution in China shows that, in addition to the more obvious physical toll, air pollution can also have serious negative effects on mental health and cognition, significantly reducing a person’s happiness and their scores in verbal and mathematical tests.
新德里遠非唯一一個。針對中國空氣污染影響的一項研究顯示，除了更明顯的身體傷害，空氣污染還可能給心理健康和認知能力帶來嚴重負面影響，從而顯著降低人們的幸福感以及他們在語文和數學測試中的得分。
Such deleterious mental effects have serious negative consequences for livelihoods and human capital development, suggesting that development strategies should go beyond the traditional focus of boosting GDP in the developing word.
這類有害的心理影響對人們的生計和人力資本發展具有嚴重負面後果，似乎表明，發展戰略應超越對提高發展中國家國內生產總值(GDP)的傳統關注。
India’s recent pollution emergency is the most dramatic incidence of hazardous air pollution, but smoggy skies have been a cause of growing concern in most developing countries.
印度最近的污染緊急狀態是最具戲劇性的有害空氣污染事件，但霧濛濛的天空一直是讓多數發展中國家越來越擔憂的一件事。
Major cities across the developing world — from Thailand, to Brazil, to Nigeria — frequently experience pollution at several times the WHO safe limits. In fact, 98 per cent of cities with more than 100,000 residents in low and middle-income countries fail to meet the WHO’s air quality guidelines.
發展中國家（從泰國、巴西到尼日利亞）大城市的空氣污染程度經常是WHO安全上限的好幾倍。實際上，在中低收入國家的居民超過10萬的城市中，有98%達不到WHO的空氣質量標準。
China’s extreme levels of air pollution are well recognised, and examining the effects provides clear warnings for other countries seeking fast growth through rapid industrialisation.
中國的極端空氣污染水平是公認的，考察其影響，將爲尋求通過快速工業化實現快速增長的其他國家提供明確警告。
We used nationally representative longitudinal surveys on mental health and cognition, matched with daily air quality data for the time and place of interviews, to see what pollution does in a given time to individual happiness and cognitive performance. Because each person in our survey was observed multiple times, we can control for the effect of individual characteristics on the outcome variables.
我們利用具有全國代表性的精神健康和認知縱向調查，結合訪談當時當地的每日空氣質量數據，考察了給定時間污染對個人幸福感和認知表現的影響。由於我們在調查中對每個受訪者都進行了多次觀察，我們能夠控制個體特徵對調查結果變量的影響。
We found that worsening air quality in China led to a decrease in happiness that day equivalent to about 10 per cent of the reduced happiness one would experience from a negative major life event such as divorce.
我們發現，中國不斷惡化的空氣質量造成的當日幸福感下降程度，相當於遭遇離婚等負面人生大事的10%左右。
The poor air quality across much of China that has accompanied rapid industrialisation and breakneck GDP growth could help to explain why several surveys have found stagnating or falling happiness in China since 2004.
在中國很多地區，糟糕的空氣質量伴隨着快速工業化以及迅猛GDP增長，這可能有助於解釋爲什麼有多項調查發現，自2004年以來中國的幸福感出現停滯或下降。
Air pollution also significantly inhibits cognitive performance. We found that individuals exposed to polluted air when taking tests scored lower on both verbal and maths tests than when they were conducted under a clear sky.
空氣污染還顯著抑制了認知表現。我們發現，在接受測試時處於空氣污染環境的個人在語文和數學測試中的得分，低於他們在晴朗天空下接受測試的結果。
The cumulative effect of pollution on test scores is even more pronounced than the immediate effect. An increase in the mean air pollution index for three years before testing had seven times the negative impact on scores than did a higher air pollution index on the testing day alone.
污染對於測試得分的累積影響甚至比即時影響還要明顯。如果在測試之前的3年期間平均空氣污染指數已然提高，其對得分的負面影響，是空氣污染水平僅僅在測試當天較高的7倍。
The worse cumulative impact suggests that short-term measures to reduce pollution at times when enhanced mental capacity is needed, would do little to address the longer-term effects of exposure to harmful air.
累積影響更嚴重似乎表明，在需要較強智力時採取短期措施減少污染，基本上無助於解決暴露於有害空氣的較長期影響。
Similarly, though the effects on mental capacity were stronger for outdoor workers than for indoor workers, studies have shown that the smallest and most harmful air pollutants can, and do, enter buildings, so simply retreating indoors cannot spare us the ill effects.
同時，儘管空氣污染對戶外工作者智力的影響超過室內工作者，但不止一項研究發現，顆粒最小、最有害的空氣污染物可以（而且確實會）進入建築物，因此只是躲在室內並不能讓我們擺脫有害影響。
Even though many of our findings show the connection between pollution and mental health in the moment, the high number of high pollution days each year in many developing countries suggest that these transitory effects could become more permanent.
儘管我們的很多調查發現顯示，污染與心理健康之間的關係是暫時的，但很多發展中國家每年嚴重污染天數之多似乎表明，這類短暫影響可能會變得更具永久性。
The stronger cumulative than immediate effect of pollution on cognitive abilities indicates that short-term measures such as restricting traffic or discouraging citizens to go outdoors will not be enough to clear the haze from our minds and lift our spirits.
污染對認知能力的累積影響比即時影響更強烈說明，限制交通或勸市民不要外出等短期措施，不足以驅散我們頭腦中的一團霧水，並讓我們精神振作。
More broadly, policymakers must consider the trade-offs of economic growth at the expense of our environment for both our physical and our mental health.
更廣泛地說，政策制定者在掂量經濟增長與環境退化之間的取捨時，必須考慮我們的身體和心理健康兩方面。
Rapid economic development in recent years has brought millions out of poverty, drastically reducing hunger, disease and mortality. But in much of the world this rapid growth has brought with it hazardous levels of pollution.
近年的快速經濟發展讓數以百萬計的人脫離貧困，大大減少了飢餓、疾病和死亡率。但在世界的很多地區，這種快速增長也帶來了有害的空氣污染。
Previous research has linked cumulative exposure to pollution to Alzheimer’s disease and other forms of dementia, as well as poor stock market performance, increased crime and reduced life expectancy.
以往的研究還發現，長期暴露於污染與阿爾茨海默病和其他老年癡呆病症；與股市表現低迷、犯罪率上升和預期壽命變短存在關聯。
Such negative side effects of industrial growth have measurable impacts on livelihoods and general welfare. As developing nations strive to improve the lives of their citizens, the downsides of growth strategies should be part of the calculation.
工業增長造成的這類負面副作用，對人們的生計和福祉有着可衡量的影響。隨着發展中國家努力改善人民生活，增長戰略的弊端應該是考量的一部分。
Xiaobo Zhang is a senior research fellow at the International Food Policy Research Institute and professor of economics in the National School of Development at Peking University.
本文作者是國際食物政策研究所(IFPRI)高級研究員、北京大學國家發展研究院(National School of Development)經濟學教授
