Yuan Si, vice-chairman of the Environment Protection and Resources Conservation Committee

"PM 2.5 volume has reached more than 100 during the night while it only registers around 30 to 50 in the daytime."

"We noticed this phenomenon after collecting three days' PM 2.5 data (in the city). It's not easy to come to a conclusion due to the difficulty in obtaining evidence. We discussed during the return trip to Beijing why the peak is appearing at night rather than daytime in which most automobiles are on the road but contribute only 20 to 30 percent PM 2.5."

"We've discussed how to explain this issue, while the local government official told us there are discharges without authorization (in the city)."

Yang Dongliang, Minister of State Administration of Work Safety

"The situation on coal production safety is still tough and complicated. Successfully preventing a death is an achievement. The problem will not be ignored as long as accidents causing death exist.

"The nation is still confronted with grave and complicated challenges in coal mine work safety as the authorities aim to achieve a zero-death target."

Wan Gang, Minister of Science and Technology

"There were 49 technology start-ups established daily in Beijing's Zhongguancun Science Park last year, contributing to the "grassroots entrepreneurship and mass innovation" proposed by the government.

Video: Liu Zheng

Editing: Liu Zheng