World Environment Day celebrations kicked off on Wednesday in Hangzhou, Zhejiang province, the host city of the annual general meeting of the China Council for International Cooperation on Environment and Development.

This year, the event was themed "Beat Air Pollution" and was aimed at helping people understand different types of pollution and how it affects their health.

China, with its growing green energy sector, has emerged as a climate leader, according to the United Nations Environment Programme.

By hosting World Environment Day 2019, the Chinese government was able to showcase its innovation and progress toward creating a cleaner environment.

The country has hosted World Environment Day before. In 1993 in Beijing, the theme was "Poverty and the Environment - Breaking the Vicious Circle". In 2002 in Shenzhen, the theme was "Give Earth a Chance".

The UN held the Conference on the Human Environment, the first international conference on environmental issues, in Stockholm, Sweden, from June 5-16, 1972.

The goal was for the international community to form a basic outline on environmental challenges and ways of solving them.

On Dec 15 that year, the UN General Assembly designated June 5 as World Environment Day in its resolutions.

It urged "governments and organizations in the UN system to undertake on that day every year worldwide activities, reaffirming their concern for the preservation and enhancement of the environment, with a view to deepening environmental awareness and to pursuing the determination expressed at the conference".

The UN Environment Programme, an agency dedicated to environmental issues, was also set up on the same day.

World Environment Day revolves around different themes every year in a different host country to let the public know of that year's urgent environmental concern.

Over the years, the event's themes included the depletion of the ozone layer, hazardous waste, population and the environment, toxic chemicals, desertification and global warming. It is a major tool and force for governments to take action. Over four decades, the event has been a global stage to promote environmental awareness in more than 100 countries with millions of people involved.

On that day, the UNEP presents the Champions of the Earth Award to several outstanding environmental leaders across the world. It is deemed as the UN's highest environmental honor. Laureates can inspire people and contribute in many ways, like scientific innovation, grassroots action, political leadership or entrepreneurial efforts.

Since 2005, China has had its own themes for World Environment Day. In 2008, the global theme was "Kick the habit! Toward a low-carbon economy", while China's was "Green Olympics and Environmentally-friendly Society".

According to the Ministry of Ecology and Environment, China's theme echoes that of the UN while revolving around the work of the ministry and focus of the nation.

Usually, celebration activities for the event are varied, inspiring and creative in China. On the day, competitions of photographs, paintings, writing on environmental issues and environmental knowledge are held among teenagers.

Books and posters are gifted to the public. Art exhibitions and environmental galas are also held to highlight green lifestyles.