Du Yunpeng remembers that he and his classmates still had to do daily calisthenics on the roof of their school building when sandstorms hit the northern Chinese city of Tianjin many years ago.

"It was a painful experience," said Du, who this fall will be a junior at Amherst College in Massachusetts in the US.

Another city where he also spent his juvenile years offered more hardship. Qitaihe, in northeastern China's Heilongjiang province, is known for coal mining.

"The dust has caused many people to suffer from lung disease and cancer. Now the situation is turning better with more laws and regulations, yet the demand for coal also remains high," Du said with a sign of worry on his face.

"Man should be part of the Earth; we should not try to rule the world," the math and philosophy major told China Daily on Thursday in front of the China Pavilion near the main venue of Rio+20, the United Nations Conference on Sustainable Development.

Last Sunday, at a side event of Rio+20, Du was one of several members of the China Youth Climate Action Network who were talking about environmental activism among young Chinese. They also exchanged information with young people from the US and issued a joint declaration.

In collaboration with the Youthink Center, another group, they produced a China Youth Sustainable Development Action Report, which was delivered to Sha Zukang, secretary-general of Rio+20 and also the UN undersecretary-general for economic and social affairs.

"The youth should never feel that their voices are too low and the things they have been doing too small. Everything is possible in this world," said Wang Yanhuan, a member of Youthink Center and a student at Sun Yat-sen University in Guangzhou, in the southern province of Guangdong.

"Individual and sustainable development cannot be separated," said Wang, who paid 15,000 yuan ($2,380) in airfare to attend Rio+20 partly by free-lancing for newspapers back home.

As a major in tourism industry management, Wang said environmental protection, sustainable development and tourism all interact. She also wanted to see how a large event such as Rio+20 would affect tourism in Brazil.

Julian Wang, also a student at Amherst College, said young people are more skilled at using new technologies to spread information and raise awareness, citing examples of blogs, videos and social media tools.

"As youth, we may have less experience (than older generations), but we have more dreams, and we will always remember to make our dreams come true," he said.

Now majoring in political science and Asian studies, Wang said he would like to study international law, perhaps focusing on human rights and the environment, and then find a job with the United Nations.

For the past few days, Wang Yanhuan from Sun Yat-sen University has been asking people she met during Rio+20 to use one word to describe "the future we want". She found their thoughts vary widely. While an American businessman told her "hopeful", a man from Uganda said "equitable" and a 90-year-old Brazilian said, "Better future for more people."

Wang also believes that college students' imaginations are richer. "Once you graduate, you will have limitations because of jobs, time and mood," she said. "We are a blank paper - you can paint as much as you want."

Shane Zhao, another Amherst College student, said he discovered that young people from many countries were active at Rio+20 and that they received support from their governments.

"I know China is still a developing country and there might be not so many resources to support youth participation. I hope as the country grows stronger and the youth will have more opportunities to reach out. The whole society should show more support," he said.

Julian Wang said he hoped to see developed and developing countries trust each other more and be more united toward achieving the goal of sustainable development.

"China and the United States, which could play leadership roles, should communicate more," he said.

Contact the writers at larrylee@chinadailyusa.com and chenweihua@chinadailyusa.com