BEIJING — China’s imports of solid wastes slumped further in the first seven months of 2018 as the government stepped up enforcement of a ban on solid waste imports.

Imports of plastic, paper, and metal waste totaled 11.83 million tons for January-July, down 54.4 percent from the same period last year, according to the General Administration of Customs.

In July alone, solid waste imports were 1.85 million tons, up from 1.52 million tons in June and 1.38 million tons in May.

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 its 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 that are not substitutable.

The government banned imports of 24 types of solid waste, including plastics and paper, and has imposed tough quality restrictions on other recyclable materials.