Apartment blocks are pictured on a hazy day in Wuqing district of Tianjin, China, December 10, 2016. REUTERS/Jason Lee

BEIJING (Reuters) - Beijing’s environmental watchdog is considering a ban on the use of trucks to transport coal and closing coal storage facilities in Tianjin, one of China’s busiest ports, a researcher with the agency said, in what would be a drastic move to tackle smog.

The city’s Environmental Protection Bureau has not made a formal proposal to the municipal government of Tianjin, Zhou Yangsheng, researcher with the agency told a coal industry briefing on late Monday.

He did not give an estimate on when a decision might be made on the move.

If implemented, it would be the latest in a series of extreme steps taken by the capital city government to cut air pollution in and around the smog-plagued capital Beijing.

The area surrounding the capital and its neighbor Tianjin in Hebei province is the most polluted in the world’s second-largest economy despite mounting efforts to control traffic and shut down coal-fired power plants and steel mills.

Tianjin port, China’s second largest by cargo volume, is the key hub for trading 100-million-tonnes a year of sea-borne coal and domestic coal that flows south from Inner Mongolia.

The proposal could reduce coal volumes at Tianjin by as much as 43 million tonnes, incurring a loss of 400 million yuan ($58 million) for the city, Yangsheng said, although ports in other parts of China would take the lost business.

Closing storage facilities and prohibiting trucks would also likely force shippers and traders to find alternative routes and modes of transport, like rail.

The municipal government of Tianjian did not respond to a request for comment on the proposal.