China's capital city Beijing has witnessed several days of blue sky in the past week, which led to photos of the unusual phenomenon becoming a hit on social media.

Authorities say more measures will be taken to maintain the so-called "Beijing Blue".

People have been sharing photos of the blue skies in Beijing on the Internet over the past few days.

Posts on the topic of "Beijing Blue Sky" have been viewed millions of times on social media.

Su Wei from the National Development and Reform Commission or NDRC says all parties need to work together to maintain the "Beijing Blue".

"The fine weather has lasted for quite a few days in Beijing. Meanwhile, the plants in surrounding areas are still doing good too. With our concerted efforts, I believe the fine weather will continue. The city's economic growth will be gradually decoupled from carbon emissions. We are working towards that goal."

The NDRC also says China aims to cut carbon intensity by 45% in 2020 compared to 2005 levels.

Carbon Intensity is often measured by the amount of energy used per unit of GDP.

Experts say the fine weather can to some extent be attributed to the coordinated mechanism of air pollution control in Beijing-Tianjin-Hebei region.

Zhao Hualin from Ministry of Environmental Protection says the overall design is important to the coordinated development of Beijing-Tian-Hebei region.

"The environment problems cannot be solved without an overall design of coordinated development. First, an environmental management mechanism should be established in this region. Second, enforcement regulations should be refined. Third, a collaborative funds mechanism should also be established in this region."

According to the Beijing Environmental Protection Bureau, the central authority has allocated 5.9 billion yuan to control air pollution in Beijing-Tian-Hebei and the surrounding areas.

China marked its third National Low-Carbon Day on June 15, two days ahead of "World Low-Carbon Day."

The theme of this year's Low-Carbon Day was "Low-Carbon cities: livable and sustainable".