?[By Jiao Haiyang/China.org.cn]

Editor's note: A new study says air pollution has shortened the life expectancy of Chinese in the north by 5.5 years. Although the details of the finding are open to academic debate, Dr Steinbock's article rightly points to the urgent need for China to go green.

All global megacities need robust growth and rising income levels. Over time, no megacity can rely on growth at the expense of life expectancies.

According to a new pioneering study, air pollution in northern China has caused the loss of 2.5 billion years of aggregate human life expectancy in the 1990s.

In the past, comparable studies on pollution effects in China have relied on long-term parallels in the United States and Europe. Furthermore, the impact effects have been largely qualitative, meaning no numbers.

In contrast, the new study - which was co-authored by Chinese (Yuyu Chen, Hongbin Li), Israeli (Avraham Ebenstein) and US researchers (Michael Greenstone) - is based on long-term mainland data and it puts numbers on projections.

Due to pollution impact, Chinese in the north have not only suffered from higher rates of lung cancer, heart attacks and strokes, but their life expectancy has been shortened by an average of 5.5 years.

Tale of two cities

In Shanghai, a lovely, relatively pollution free summer day translates to a "moderate" air quality index of 60-100, which causes respiratory symptoms to only sensitive individuals. However, "unhealthy" levels for sensitive groups (AQI, 101-150) and for all residents (AQI, 151-200) are not exactly uncommon either.

In northern China, the toxic smog became an issue of national concern in January, when air pollution soared to record levels in Beijing, compelling residents to hoard face masks and air filters.

As pollution soared beyond the air quality index and particulate matter levels rose above 700 micrograms per cubic meter, the smog reduced visibility across the city.

The facts have been "known" in the past. But the new estimates are less reliant on Western experiences or speculative projections.

What the new study confirms is that a high level of air pollution can reduce the lives of people who are exposed to it. The adverse impact is due to the particulates generated by burning coal.

Relying on a quasi-experimental method, the researchers discovered very different life expectancy figures for an otherwise similar population south of the Huaihe River, where government policies did not cover for the areas to have coal-powered central heating.

The bottom line is that your life expectancy depended significantly on which side of the river you happened to live.

The study also includes a generalized metric that is applicable to any country's environment. The message of the metric is alarming. Basically, it says that every additional 100 micrograms of particulate matter per cubic meter in the atmosphere lowers life expectancy at birth by three years.

Some lessons

Assuming the conclusions of such studies are valid, what are the implications for emerging global mega cities, such as Shanghai?

First of all, economic growth and detrimental pollution come with trade-offs. Rapid growth that relies on pollutants has significant, adverse long-term consequences.

In Shanghai, these facts underscore the urgency of the transition from cost-efficiencies to innovation-driven growth.

Second, in the past three decades, cost-efficient off-shoring has resulted in great profits to investors, but led to the "hollowing-out" of the US industrial base. In contrast, Shanghai has sought to retain a thriving manufacturing base.

By the same token, Shanghai should not only upgrade old polluting industries and move toward new less-polluting service industries, but it should also prioritize those emerging areas that rely on green and clean technologies.

Third, pollution recognizes no borders, as even Singaporeans recently found out as their pollution soared to hazardous levels (AQI, above 400), due to illegal fires from slash-and-burn land clearing in Indonesia.

Similarly, Shanghai occasionally suffers from heavy pollution from proximate regions.

Consequently, protecting the mega city requires not just policies targeting cities and municipalities, but the entire region.

One of the most important characteristics of any global mega city is its high-level human capital. That, in turn, translates to a high degree of human development, which is typically based on education, income and life expectancy.

While educational aspirations and rising incomes are necessary for human development, they are not sufficient.

High quality of life cannot be based on shortened life spans.

Dan Steinbock is the research director of international business at the India, China and America Institute (USA) and a visiting fellow at the Shanghai Institute for International Studies (China).