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 restrictions¹ put in place.

11月，印度医学协会(Indian Medical Association)宣布由于空气污染严重，新德里进入公共健康紧急状态。学校停课，紧急交通限制措施出炉。

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.

新德里的空气污染程度超出世界卫生组织(WHO)安全上限近30倍，其对肺的损害超过每日吸两包香烟。

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 toll², 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.

新德里远非唯一一个。针对中国空气污染影响的一项研究显示，除了更明显的身体伤害，空气污染还可能给心理健康和认知能力带来严重负面影响，从而显著降低人们的幸福感以及他们在语文和数学测试中的得分。

Such deleterious mental effects have serious negative consequences for livelihoods³ and human capital development, suggesting that development strategies should go beyond the traditional focus of boosting GDP in the developing word.

这类有害的心理影响对人们的生计和人力资本发展具有严重负面后果，似乎表明，发展战略应超越对提高发展中国家国内生产总值(GDP)的传统关注。

India’s recent pollution emergency is the most dramatic incidence of hazardous⁴ air pollution, but smoggy skies have been a cause of growing concern in most developing countries.

印度最近的污染紧急状态是最具戏剧性的有害空气污染事件，但雾蒙蒙的天空一直是让多数发展中国家越来越担忧的一件事。

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.

发展中国家（从泰国、巴西到尼日利亚）大城市的空气污染程度经常是WHO安全上限的好几倍。实际上，在中低收入国家的居民超过10万的城市中，有98%达不到WHO的空气质量标准。

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.

中国的极端空气污染水平是公认的，考察其影响，将为寻求通过快速工业化实现快速增长的其他国家提供明确警告。

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 cognitive⁵ performance. Because each person in our survey was observed multiple times, we can control for the effect of individual characteristics on the outcome variables.

我们利用具有全国代表性的精神健康和认知纵向调查，结合访谈当时当地的每日空气质量数据，考察了给定时间污染对个人幸福感和认知表现的影响。由于我们在调查中对每个受访者都进行了多次观察，我们能够控制个体特征对调查结果变量的影响。

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.

我们发现，中国不断恶化的空气质量造成的当日幸福感下降程度，相当于遭遇离婚等负面人生大事的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 stagnating⁶ or falling happiness in China since 2004.

在中国很多地区，糟糕的空气质量伴随着快速工业化以及迅猛GDP增长，这可能有助于解释为什么有多项调查发现，自2004年以来中国的幸福感出现停滞或下降。

Air pollution also significantly inhibits⁷ 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.

空气污染还显著抑制了认知表现。我们发现，在接受测试时处于空气污染环境的个人在语文和数学测试中的得分，低于他们在晴朗天空下接受测试的结果。

The cumulative⁸ effect of pollution on test scores is even more pronounced than the immediate⁹ 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.

污染对于测试得分的累积影响甚至比即时影响还要明显。如果在测试之前的3年期间平均空气污染指数已然提高，其对得分的负面影响，是空气污染水平仅仅在测试当天较高的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.

累积影响更严重似乎表明，在需要较强智力时采取短期措施减少污染，基本上无助于解决暴露于有害空气的较长期影响。

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 pollutants¹⁰ can, and do, enter buildings, so simply retreating indoors cannot spare us the ill effects.

同时，尽管空气污染对户外工作者智力的影响超过室内工作者，但不止一项研究发现，颗粒最小、最有害的空气污染物可以（而且确实会）进入建筑物，因此只是躲在室内并不能让我们摆脱有害影响。

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.

尽管我们的很多调查发现显示，污染与心理健康之间的关系是暂时的，但很多发展中国家每年严重污染天数之多似乎表明，这类短暂影响可能会变得更具永久性。

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 haze¹¹ from our minds and lift our spirits.

污染对认知能力的累积影响比即时影响更强烈说明，限制交通或劝市民不要外出等短期措施，不足以驱散我们头脑中的一团雾水，并让我们精神振作。

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.

更广泛地说，政策制定者在掂量经济增长与环境退化之间的取舍时，必须考虑我们的身体和心理健康两方面。

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.

近年的快速经济发展让数以百万计的人脱离贫困，大大减少了饥饿、疾病和死亡率。但在世界的很多地区，这种快速增长也带来了有害的空气污染。

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 expectancy¹².

以往的研究还发现，长期暴露于污染与阿尔茨海默病和其他老年痴呆病症；与股市表现低迷、犯罪率上升和预期寿命变短存在关联。

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.

工业增长造成的这类负面副作用，对人们的生计和福祉有着可衡量的影响。随着发展中国家努力改善人民生活，增长战略的弊端应该是考量的一部分。

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.

本文作者是国际食物政策研究所(IFPRI)高级研究员、北京大学国家发展研究院(National School of Development)经济学教授