The study was led by University of Delaware’s James Corbett, and included an international team of researchers from the Finnish Meteorological Institute (FMI), Rochester Institute of Technology (RIT) in New York and Energy and Environmental Research Associates.

Using high-resolution emissions inventories, integrated atmospheric models, and health risk functions, we assess ship-related PM_2.5 pollution impacts in 2020 with and without the use of low-sulphur fuels. Cleaner marine fuels will reduce ship-related premature mortality and morbidity by 34 and 54%, respectively, representing a ~ 2.6% global reduction in PM_2.5 cardiovascular and lung cancer deaths and a ~3.6% global reduction in childhood asthma. Despite these reductions, low-sulphur marine fuels will still account for ~250k deaths and ~6.4 M childhood asthma cases annually, and more stringent standards beyond 2020 may provide additional health benefits.

—Sofiev et al.

Ship air pollution effects are greatest in areas where heavily travelled ship routes exist in, and next to, densely populated communities. Some key regions include China, Singapore, Panama, Brazil and coastlines of Asia, Africa and South America.

Reduction in annual PM2.5 concentrations in 2020 due to low-sulfur fuel standards. Model results showing the reduction in annual PM2.5 concentrations in micrograms per cubic meter due to the implementation of the International Maritime Organization’s global fuel sulfur standard in 2020. Sofiev et al. Click to enlarge.

Roughly 14 million annual cases of childhood asthma are estimated to be related to global ship pollution using current fuels. The change to cleaner ship fuels will reduce the ship-related childhood asthma cases by half.

Additionally, shipping pollution is estimated to contribute to 400,000 premature deaths from lung cancer and cardiovascular disease annually. This is about 7-8% of the global health burden caused by air pollution. Reducing ship sulfur emissions cuts these other global health related impacts, too, avoiding about one-third of the annual cardiovascular disease and lung cancer deaths from shipping air pollution.

Avoided mortality due to fuel sulfur standards. Map of avoided mortality (cardiovascular disease and lung cancer) from reduced ship PM2.5 emissions due to implementation of the IMO low-sulfur fuel standards in 2020. Annual avoided mortality minimum and maximum are 0 and 800, respectively. Sofiev et al. Click to enlarge.

Researchers used a state-of-the-art model of ship traffic based on satellite records to determine where ship activity was producing emissions, and adjusted to account for expected vessel emission growth rates by the year 2020. They used another high-resolution model to see how ship emissions would mix and chemically transform in the atmosphere, how they disperse and how they contribute to air quality where people live.

To compute how additional pollution from ships increases risk of disease for exposed populations, especially those living in coastal communities or along major shipping lanes and far inland in some nations like India, the team incorporated important underlying health information from the World Health Organization and Global Asthma Network.

Our results show that these regulations are beneficial, but also that more air pollution health benefits remain possible with less-polluting ships.

—James Winebrake, professor and dean at RIT

Refining industries will invest in the necessary technology to produce, and shipping will invest to adapt engine systems to use, the cleaner fuels. These costs will be borne by consumers in the prices of goods they buy. Corbett believes that improved global health is worth the investment.

While the health benefits are clear, the research also quantifies tradeoffs in terms of climate.

Sulfur dioxide emissions from ships create small particles. These sulphur containing particles reflect sunlight and help form brighter clouds, creating a global effect—radiative cooling—that temporarily diminishes the warming effects of carbon dioxide.

Lower sulphur fuels also reduce radiative cooling from ship aerosols by ~80%, equating to a ~3% increase in current estimates of total anthropogenic forcing. Therefore, stronger international shipping policies may need to achieve climate and health targets by jointly reducing greenhouse gases and air pollution.

—Sofievet al.

Direct radiative forcing due to low-sulfur fuel standards. Direct radiative forcing in mW m−2 at the top of the atmosphere from scattering sulphate and nitrate aerosols due to implementation of the IMO low-sulfur fuel standards for ships. Global mean is 3.9 mW m−2. Sofiev et al. Click to enlarge.

At the same time, shipping activity is expected to increase with global trade and continue to produce harmful air emissions and greenhouse gases. Despite the upcoming reductions, low-sulfur marine fuels will still account for approximately 250,000 deaths and 6.4 million childhood asthma cases annually, so more stringent standards beyond 2020 may be needed to provide additional health benefits.

This study was funded in part by ClimateWorks Foundation, the Academy of Finland, with in-kind support from the Finnish Meteorological Institute and Energy and Environmental Research Associates, LLC.

Resources

• Mikhail Sofiev, James J. Winebrake, Lasse Johansson, Edward W. Carr, Marje Prank, Joana Soares, Julius Vira, Rostislav Kouznetsov, Jukka-Pekka Jalkanen & James J. Corbett (2018) “Cleaner fuels for ships provide public health benefits with climate tradeoffs” Nature Communications Volume 9, Article number: 406 doi: 10.1038/s41467-017-02774-9