The Chinese government has introduced a tightened ban on solid waste imports, according to an official document.

Effective on December 31, 2018, 32 types of solid waste will be banned from imports, according to the document released by the Ministry of Ecology and Environment, the Ministry of Commerce, the National Development and Reform Commission, and the General Administration of Customs.

The newly added products include hardware, ships, auto parts, waste and scrap of stainless steel, titanium and wood.

China's imports of solid waste slumped further in the first 10 months of 2018 as the government stepped up enforcement on a ban on solid waste imports.

The country began importing solid waste as a source of raw materials in the 1980s and for years has been the world's largest importer, despite a weak capacity in garbage disposal. Some companies illegally bring foreign waste into the country for profit, posing a threat to the environment and public health.

Given rising public awareness and China's green development drive, the government last year decided to phase out and halt such imports by the end of 2019, except for those containing resources not substitutable.