China aims to eradicate severe smog by 2030, but more time and regulations are needed to make constant blue skies a reality, scientists from the Chinese Academy of Sciences said on Wednesday.

Coal-burning, car exhaust fumes and emissions from industrial production are the main causes of smog, therefore, implementing stricter laws on pollutant emissions, improving fuel efficiency and reshaping China's energy structure are crucial to improving the country's overall air quality, the scientists said at a smog research conference in Beijing.

Since 2013, the number of days with severe smog - defined as days when the air quality index is 300 or higher - has gradually decreased, said He Hong, a researcher at the academy's Institute of Urban Environment. China's national air quality has also improved, especially in Beijing and its surrounding regions, he said.