While global financial markets remain focused on the credit crunch in the US, another market-rattling problem could be brewing thousands of miles away – in China.

Many investors expect a post-Olympic economic slowdown in China, as infrastructure spending slows and activities related to the run-up to the games wane. But a pullback could materialise before the Olympics, not after.

A pre-Olympic slowdown may be on the cards if the government is forced to act aggressively to reduce pollution in and around Beijing. As any visitor to Beijing quickly realises, air pollution is an acute problem, and one China wants to tackle swiftly, lest its Olympic coming-out party is shrouded in smog.

Because of the Olympics, China has worked hard to go green. Around Beijing, various polluting industries have either been relocated or refitted with more energy-efficient technologies. Coal-burning plants have been converted to cleaner fuels, and more stringent vehicle emission standards have been instituted. Sizeable funds have been pumped into Beijing's public transport. As a result, the air quality has improved.

However, doubts persist about China's environment, and for good reason. The challenge before the nation is herculean, considering that China is home to 16 of the world's 20 most polluted cities. As much as 10 per cent of China's farmland is polluted; roughly 700m of China's people drink water contaminated with waste. In 2007, China surpassed the US to become the world's largest emitter of greenhouse gases.

In Beijing, soaring car ownership and the lingering presence of many heavy industries are the main causes of air pollution. In addition, Beijing is surrounded by mountains that prevent pollutants from dispersing and is subject to severe sandstorms.

Against this backdrop, the United Nations has warned that high levels of air pollution are a “legitimate concern” for anyone participating in the games. The International Olympic Committee has also expressed its concerns and has said that some events may have to be rescheduled. Haile Gebrselassie, the men's marathon world record holder, is threatening not to run if conditions are not safe. All of the above has not been lost on Chinese officials. According to Bloomberg, the government has already decided to close several coal-fired power plants, cement factories and chemical manufacturers about a month before the games.

Similarly, factories producing steel, building materials and other pollution-generating commodities may be shut down or have their production limited prior to the Olympics. Also, the government is expected to ban more than 1m cars from the capital's streets before and during the games. Construction activity is expected to be curbed sooner rather than later.

To what extent these measures slow the pace of real growth in Beijing in particular and China in general remains uncertain. Yet there is little doubt that should the government mandate a two- or three-month, pre-Olympic reduction in industrial output, the general economy will feel some of the pain. The macro impact would not be insignificant, since Beijing and China's north-east account for about 30 per cent of the nation's industrial production.

In the end, the more China struggles to improve its environment, the greater the potential for more draconian measures. The games are too symbolic for China not to act aggressively. Hence, if the air does not start to improve by the spring, China may have no choice but to slam on the industrial brakes.

Such a scenario would stun a global financial community long-accustomed to China growing by 10 per cent or more a year. In particular, a pre-Olympic slowdown could result in a deflationary shock to the global commodity markets, triggering an abrupt decline in commodity prices. In turn, real growth in many high-flying commodity nations would weaken. The upshot: weaker global growth and softer global earnings in 2008.

All of the above is another way of saying that there is a great deal riding on China and its battle to clean the air before this August.

The writer is chief market strategist at Bank of America

尽管全球金融市场仍在关注美国的信贷危机，但在数千英里外的中国，另一个令市场不安的问题可能正在酝酿之中。

许多投资者预计，在奥运会之后，随着基础设施支出放缓，奥运会相关活动退潮，中国的经济增长将会减速。但是，这种减速可能在奥运会之前就会成为现实，而非在奥运会之后。

如果中国政府被迫采取激进手段，减少北京及周边地区的污染，那么奥运之前的经济减速就会成为可能。任何前往北京的人都会很快意识到，空气污染是一个严重问题，也是中国希望迅速解决的问题，以免奥运会的开幕式笼罩在雾霭之中。

由于奥运会，中国已采取了大量环保措施。在北京周边，各类污染企业要么已经搬迁，要么进行了技术改造，改用能效更高的技术。燃煤工厂已转向更清洁的燃料，更严格的汽车排放标准也已经制定出来。政府还向北京的公共交通投入了大量资金。这些措施的结果是，北京的空气雷竞技百科 已有所改善。

不过，人们仍然对中国的环境持怀疑态度，而且理由充分。鉴于在全球20个污染最严重的城市中，中国就占了16个，因此中国面临的挑战非常巨大。中国多达10%的农田被污染；大约7亿中国人的饮用水中含有污物。2007年，中国取代美国成为全球最大的温室气体排放国。

在北京，汽车保有量不断飙升，许多重工业企业迟迟没有搬迁，成为空气污染的主要原因。此外，北京四周环山，不利于污染物的扩散，并且北京遭遇严重的沙尘暴袭击。

在这种背景下，联合国已经发出警告，对任何参加奥运赛事的人来说，严重的空气污染都是一个“合理的担忧”。国际奥委会(International Olympic Committee)也表达了自己的担忧，并且表示，一些赛事可能不得不改期。男子马拉松项目世界纪录保持者海利?盖布雷塞拉西(Haile Gebrselassie)威胁称，如果环境不安全，他将拒绝参赛。中国官员注意到了上述所有情况。据彭博(Bloomberg)报道，中国政府已经决定，在奥运会前一个月左右，将关闭数家燃煤发电厂、水泥厂和化工厂。

同样，在奥运会前，钢铁、建筑材料以及其它致污大宗商品制造厂可能也将关闭或是限产。此外，在奥运会举办之前和期间，预计中国政府将限制逾100万辆汽车驶上首都街道。预计建筑活动受到限制的时间只会提早，而不是推迟。

这些措施将在多大程度上放缓北京乃至整个中国的实际增长步伐，目前仍不能确定。不过，几乎没有人怀疑，如果中国政府要求在奥运会前减少两三个月的工业产出，整体经济将会受到一定程度的影响。宏观影响可能不容忽视，因为北京和中国东北地区的工业产出约占全国总产出的30%。

总而言之，中国越是努力改善环境，实施更严厉措施的几率就越大。奥运会的象征意义之高，让中国不得不积极采取行动。因此，如果到今年春季，空气雷竞技百科 还没有开始改善，中国或许将别无选择，只能对工业猛踩刹车。

对于长期以来已习惯于中国年增长率在10%以上的全球金融市场来说，这种情形可能会让它们目瞪口呆。特别是，奥运会前的中国经济增速放缓，可能对全球大宗商品市场形成通缩冲击，引发大宗商品价格突然下跌。进而，许多大宗商品生产国的实际增长可能走软。其结果是：2008年全球增长走弱，全球业绩走软。

上述种种情况从另一个侧面表明，有很多因素依赖于中国以及中国在今年8月份前净化空气的努力。