BEIJING -- China saw a significant improvement in its ecological environment amid anti-pollution efforts and a push for green growth, an official said Wednesday.

Major pollutant discharge recorded a drastic drop, with the overall emissions of sulfur dioxide and nitrogen oxides and the demand for chemical oxygen in 2017 plunging by 72 percent, 34 percent and 46 percent, respectively, compared with the readings from 2007, said Zhao Yingmin, vice minister of ecology and environment, citing data from the communique of the second national survey on sources of pollution.

From 2007 to 2017, the country's production output expanded, while pollution emissions shrank drastically, pointing to a higher economic quality, according to Zhao.

During the period, among key pollution-intensive sectors, the paper-making sector saw its chemical oxygen demand sink by 84 percent, while the iron and steel and cement industries reported a 54 percent decrease in emissions of sulfur dioxide and 23 percent decrease in emissions of nitrogen oxides, respectively.

China carried out the second national survey on sources of pollution from 2017 to 2019 as part of its efforts to get a clear picture of pollutant sources in its effort to promote green development.