新的航运规则旨在减少空气污染 但可能损害海洋

New shipping rules aimed at reducing air pollution will take effect in January 2020. The rules, put in place by the International Maritime Organization, or IMO, will change the kind of fuel that ships can use.

Ships, for the most part, will no longer be able to use fuels with a sulfur content above 0.5 percent. Current rules permit a sulfur content of around 3.5 percent.

The IMO's stated goal is to reduce air pollution.

However, experts and civil society leaders warn that the rules could have a bad side effect. Ship crews might dump more sulfur and nitrates into the ocean.

After January 2020, ships will still be able to use higher-sulfur fuel if they have pollution cleaning devices called scrubbers.

There are two kinds of scrubbers: open-loop scrubbers and closed-loop scrubbers. Open-loop scrubbers use water to remove sulfur coming through a ship's smokestack and pump the waste into the sea. Closed-loop scrubbers keep most of the water used in the cleaning process on the ship for disposal later at a port.

A few countries will ban the use of open-loop scrubbers. Singapore and Fujairah in the United Arab Emirates are two examples. China is also set to extend a ban on scrubber discharge to coastal areas.

"Were open-looped scrubbers ever a really good idea?" Bill Hemmings of the Clean Shipping Coalition asked industry figures at the IMO's headquarters in London.

Years of studies have examined whether open-loop scrubbers hurt human and marine life by putting dangerous chemicals into the water. The results, so far, have not been clear. The IMO has supported further study into the environmental impact of scrubbers.

"It's a bit of a blind spot, and the optics of it are not great," said Alan Gelder to the Reuters news agency. Gelder is vice president of refining at consulting company Wood Mackenzie

"Though some studies suggest the impact of open-loop scrubbing is going to be very small given the great volume of seas, which already contain many sulphates, what it's doing is solving air pollution by producing a marine pollutant instead."

The stated aim of the new rules is to improve human health.

A study last year said that ship pollution with current sulfur levels caused about 400,000 premature deaths from lung cancer and cardiovascular disease. The study, which appeared in the journal Nature, also said the pollution caused about 14 million cases of childhood asthma every year. After 2020, experts think those numbers will fall to about 250,000 and 6.4 million, respectively.

Some people, however, are still doubtful of the new rules.

One oil trader told the Reuters news agency that the "huge changes" might not be as helpful as some might think.

"In the end you can still buy a piece of kit that just dumps it [pollution] in the water," he said.

I'm John Russell.

Noah Browning reported on this story for Reuters. John Russell adapted it for Learning English. Mario Ritter Jr. was the editor.