China is waging war on pollution, closing factories and targeting dirty coal-fired power plants, but its ports are pumping out pollution virtually unchecked, according to a report by a US environmental group.

The thousands of ships that ply China’s waterways are delivering a toxic cocktail of pollution, with just one ship capable of emitting the same pollution as half a million trucks each day, the report by the Natural Resources Defense Council (NRDC) said.

“China is paying a high price for pollution associated with shipping,” it said, citing studies in Hong Kong and Shenzhen.

“An estimated 1.2 million premature deaths in China in 2010 were caused by ambient air pollution, and shipping is a significant source of these air pollution and health problems…”

Seven of the world’s 10 largest ports are in China, with more than a quarter of the planet’s maritime cargo passing through China, and the heavily populated coastal cities such as Guangzhou, Shanghai and Shenzhen are among the most polluted.

“With ocean going ships allowed to burn fuel with sulphur levels that are 100 to 3 500 times higher than permitted in on-road diesel, one container ship cruising along the coast of China emits as much diesel pollution as 500 000 new Chinese trucks in a single day,” said the NRDC report.

Most ships at Chinese ports use cheap bunker fuel, which is high in sulphur, and port vehicles and equipment are powered by diesel fuel. The combined exhaust from ships and ports contain high levels of diesel particulate matter, oxides of nitrogen and oxides of sulphur, said the NRDC.

“These emissions are known to cause cancer and are associated with a wide range of respiratory and cardiovascular illnesses,” said the report.

But little has been done to stem shipping pollution on a national level in China, and only a few cities have begun drawing up plans to address the problem, according to the NRDC.

Hong Kong is enforcing strict low-sulfur standards for local vessels, while Shenzhen has announced clean-up plans.

Other port cities and regions like Shanghai, Qingdao, Guangdong, Jiangsu, and Shandong provinces have issued plans to promote shore power, electrification of port equipment, and the use of electric or natural gas-powered trucks.

But the report questions the effectiveness of such plans without detailed, and agreed to, goals, penalties and incentives by ports and city authorities.

Globally, environmental regulations for ships are overseen by the International Maritime Organisation (IMO). But while the IMO has cut pollution by implementing special emissions control zones in America and Europe, which use low-sulfur marine fuels as standard, Asia has been left untouched.

And the concern is that Chinese ports will be reluctant to implement pollution controls for fear of losing trade.

“Unless port cities cooperate on regional emission control measures, the fear that ships will shift to less regulated ports could prevent port cities from adopting stricter measures,” the report said.

“If regulation were to drive ships to other ports, such “leakage” would only shift pollution from one port to another and seriously undermine the overall effectiveness of clean port and shipping measures that have been adopted.”