By Rogerio Wassermann
BBC Brasil, Beijing
Thick smog on the ring road in Beijing
China's unprecedented economic growth over the past 30 years has come at a huge cost to the environment.
The damage has not only been to the air the Chinese breath or the water in their rivers, but also to its reputation across the world.
But there are signs that China may now be serious about tackling pollution to prove to the world that it can develop while causing less damage to the environment.
BBC Brasil travelled to China, which recently overtook the United States as the world's biggest emitter of carbon dioxide, as part of its series looking at where the BRIC economies - Brazil, Russia, India and China - will be in 2020.
China is today the world's biggest consumer of coal, the cheapest yet most polluting source of energy.
The country uses a quarter of the world's coal reserves and depends on it to provide more than two thirds of its energy needs.
The rapid growth has also altered old Chinese habits that used to be environmentally friendly.
As soon as you walk out from your hotel onto the street of Beijing you realise that the typical image of Chinese city streets being packed with bicycle-riding commuters is becoming a thing of the past.
How pollution affects China
20 of the 30 most polluted cities in the world are in China
400,000 people die of pollution related diseases each year
One third of Chinese territory is affected by acid rain
Bumper to bumper, the people of Beijing crawl to work in their cars. Each car belching out fumes into the atmosphere.
In Beijing alone, the number of cars has tripled over the past decade, with more than 1,000 new vehicles arriving on the streets of the capital every day.
In discussions for the post-Kyoto global climate treaty, China now accepts the need for mandatory targets to reduce greenhouse gasses, but with the condition that stricter rules should be applied to developed countries.
"China is no longer a closed country," says Tom Wang, spokesman for Greenpeace in Beijing.
"To keep its economic growth and its place as an important player on the international scene, it needs to acknowledge what other countries are saying about it."
According to Mr Wang, environmental damage costs the country up to 5% of its economic output each year.
The biggest victims of the pollution are the Chinese themselves.
One woman in Beijing complained about the low cloud that floats above the city centre.
A man complained about a "constant inexplicable cough".
According to the World Bank, of the 30 most polluted cities in the world, 20 are in China.
Each year more than 400,000 people die of pollution-related illnesses.
But when BBC Brasil visited Wang Xiaoming of Beijing's Environmental Protection Bureau, the mood was upbeat.
To get to the main office you walk over a glass floor under which is a model of the city showing where its monitoring points are.
Mr Wang's office is full of computer screens being studied by technicians.
He points proudly at one of the screens, which shows that pollution in the city is better than the level considered to be safe by the World Health Organisation.
And that's not all. Mr Wang says the trend for pollution has been down in the city for some time.
You walk over a model of Beijing at the Environmental Protection Bureau
According to Mr Wang, last year Beijing had 274 of what are called "blue sky days", which is when the pollution level is under the maximum level considered acceptable by the WHO. In 2007, they had 246 days of blue sky days while in 1998 they only had 100.
But it is not only air quality that is a matter of concern.
Many of the country's rivers are polluted with heavy metals, spoiling the water used for irrigation and contaminating the food chain.
Around a third of the Chinese territory is affected by the acid rain caused by pollution. The rain has a direct impact on the country's food production.
The Chinese government has started to act on these issues, mainly because environmental damage poses a threat to the economic growth of the country.
Last year the Beijing Olympics served as a platform for the Chinese government to show the world that it cares about the environment.
All of the buildings designed for the Games had "green" features such as solar power and systems for collecting rain water.
In addition, restrictions were set to limit emissions from polluting industries, and a rota-based system was put in place to reduce by half the amount of cars on the streets of Beijing.
These measures achieved what had seemed impossible: blue skies during the two weeks of the Games.
The measures adopted during the Olympics, although limited in their reach, proved the country is capable of fighting against its environmental problems if there is political will.
For David Dollar, director of the World Bank in China, the country has achieved some progress in this area, although it still faces serious problems.
"If we had had this conversation a year ago, I would have said that environmental issues were the greatest challenge faced by China and the biggest threat to the country's growth in the long term," says Dollar.
"However, what is little known is that there has been a great deal of progress on the environmental front in the last ten years. China is one of a few countries in the world that have been rapidly increasing their forest cover. It is managing to reduce air and water pollution," says Dollar.
If China can develop alternative energy sources and reduce emissions, the country might in 2020 be an example of how economic development and environmental protection can work together.