Cleaner Shipping Fuels will Prevent Millions of Childhood Asthma Cases

A new study finds tighter fuel standards for ships will have a major impact on public health globally.

James Corbett, PhD

New regulations governing the fuels used by the shipping industry will have a major impact on public health, including a 3.6% cut in the number of childhood asthma cases globally.

The International Maritime Organization, the United Nations agency charged with regulating the shipping industry, will enact a new rule in 2020 that will limit the allowable amount of sulphur in shipping fuels to 0.5%, down from 3.5%. That translates into a reduction from 35,000 parts per million (ppm) of sulphur to just 5,000 ppm.

James Corbett, PhD, a professor of marine science and policy at the University of Delaware, led the study along with colleagues in Finland and New York. He told MD Magazine the shipping industry has been behind other industries when it comes to using cleaner fuels.

“Ships are the last sector burning this higher sulphur fuel and this regulation commits them to a course that will require that they begin to use cleaner fuels,” Corbett said.

The change, however, won’t come cheap for the shipping companies who now must buy cleaner fuels. Some estimates indicate costs could rise by 60% to 100%. That’s one reason why, when the rules were first finalized in 2020, the IMO included a clause that allowed for a five-year delay if it appeared the transition wouldn’t be technologically possible by 2020.

Fearing a delay, Corbett said he and his colleagues wanted to make a clear scientific case for why the IMO should stick with the 2020 deadlines. The science, it turns out, spoke volumes.

“This paper estimates health benefits that are much, much larger than had previously been estimated,” said Corbett, who published earlier papers on the health impacts of sulphur fuels back in 2007 and 2009. “What this suggests is that there are substantial payoffs — substantial health benefits — that help policymakers understand that this action to set a 0.5% sulphur content limit for global fuels is worth it.”

The new rules are estimated to cut ship-related mortality by 34% and ship-related morbidity by 54%, thanks to reduced rates of ship-related lung cancer and cardiovascular disease. The researchers calculated that the new rules will cut ship-related childhood asthma cases by 54% globally, from their current level of 14 million cases annually.

Corbett and colleagues made their calculations based on a model of ship traffic that incorporates satellite data, adjusted to account for expected growth. Another model was utilized to calculate the chemical impacts on air quality. Those data were then analyzed alongside country-specific health data from the Global Asthma Network and the World Health Organization.

Some of the biggest impacts will take place in parts of southeast Asia, Indonesia, and India. In the United States, the impact of the new regulations will be somewhat less, since the U.S. and Canada already have special rules in place that limit sulphur to an even tougher standard — 0.1% — within 200 nautical miles of the coast. Corbett said the new rules will bring something closer to uniformity and economic equity between the rules ships must follow near North America and the rules they must follow elsewhere.

Still, while the study shows the regulatory change will have a major benefit to public health, it also demonstrates that even the cleaner fuels will still have tremendous health impacts.

The study found shipping fuels will still lead around a quarter-million premature deaths annually, and 6.4 million cases of childhood asthma. And the impact won’t just be on the coasts, but inland as well.

The study also noted that reducing sulphur emissions will result in an increase in global warming, since the particles form sulphur dioxide emissions reflect sunlight and change the chemistry of clouds, both of which have the effect of slowing down warming. Using cleaner fuel will thus speed up global warming by about 3%, the researchers found.

“Even with cleaner marine fuels after 2020, shipping activity will continue to produce harmful air emissions and greenhouse gases,” researchers concluded. “Notwithstanding the first meaningful global fuel-sulphur controls since fleets converted from coal to petroleum byproducts, energy use in global trade is expected to increase, along with air emissions from shipping.”

The study, "Cleaner fuels for ships provide public health benefits with climate tradeoffs,” was published online in Nature Communications last week.

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