In a study appearing this month in the journal Environmental Science and Technology, MIT researchers report that emissions from cars, trucks, planes and powerplants cause 13,000 premature deaths in the United Kingdom each year.
The researchers analyzed data from 2005, the most recent year for which information is available. They found that among the various sources of emissions in the country, car and truck exhaust was the single greatest contributor to premature death, affecting some 3,300 people per year. By comparison, the researchers note, fewer than 3,000 Britons died in road accidents in 2005.
The researchers found that emissions originating elsewhere in Europe cause an additional 6,000 early deaths in the U.K. annually; U.K. emissions that migrate outside the country, in turn, cause 3,100 premature deaths per year in other European Union nations. In some areas on the periphery of the U.K. — such as northern Scotland — almost all air pollution comes from the rest of Europe, the researchers say.
MIT’s Steven Barrett and his co-author Steve Yim began the study in light of recent events in the U.K.: London is currently in violation of air quality standards set by the E.U., and the British government may face significant E.U. fines if it fails to address its air pollution.
“We wanted to know if the responsibility to maintain air quality was matched by an ability to act or do something about it,” says Barrett, the Charles Stark Draper Assistant Professor of Aeronautics and Astronautics at MIT. “The results of the study indicate there is an asymmetry there.”
Dust in the wind
Barrett worked with MIT postdoc Steve Yim to analyze emissions data provided by the British government. The team divided the country’s emissions into sectors, including road transport; power generation; commercial, residential and agricultural sources; and other transport, such as shipping and aviation.
The group then simulated temperature and wind fields throughout the country using a weather research and forecasting model similar to those used to predict short-term weather. Barrett and Yim entered emissions data into the model to see how weather might disperse the emissions. They then ran another simulation — a chemistry transport model — to see how emissions from different sectors interacted.
Finally, the group overlaid their simulation results on population density maps to see which locations had the greatest long-term exposure to combustion emissions. Barrett observed that most of the emissions studied were composed of particles less than 2.5 microns in diameter, a size that epidemiologists have associated with premature death.
After road transport, the researchers found that emissions from shipping and aviation were the second greatest contributor to premature deaths, causing 1,800 early deaths annually, followed by powerplant emissions, which cause an estimated 1,700 premature deaths each year.
Barrett and Yim found that powerplant emissions have larger health impacts in northern England, where emissions from five major plants tend to congregate. In London, the researchers found that shipping and aviation emissions had a greater impact on health, possibly due to the proximity of major airports to the city.
Emissions from the country’s powerplants, which are mostly northeast of major cities and emit pollution well above ground level, are less damaging to the general population than other sources of pollution, Barrett says. In contrast, he says emissions from cars and trucks, which occur closer to where people live and work, pose a more serious risk to human health.
“People have a number of risk factors in their life,” Barrett says. “Air pollution is another risk factor. And it can be significant, especially for people who live in cities.”
Fintan Hurley, scientific director of the Institute of Occupational Medicine in Edinburgh, Scotland, says the group’s findings provide a detailed analysis of the sources of air pollution in the country. Hurley led a similar study by the Committee on the Medical Effects of Air Pollution, and says Barrett’s results are in line with that analysis. The implications, he adds, go beyond Britain’s borders.
“It’s helpful to have a detailed analysis of effects in the U.K., but outdoor air pollution from combustion sources is an important public health issue worldwide,” Hurley says. “With outdoor air pollution everybody is exposed, because fine particles and gases also penetrate indoors. It’s possible for individuals to do some things to limit their personal exposures, but the main need is to act together to reduce emissions.”
(Jennifer Chu, MIT News Office)
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The original research article is available at DOI: 10.1021/es2040416.
A new MIT-led study has been released that assesses the economic and environmental costs and benefits of desulfurizing jet fuel.
Aircraft emissions can reduce air quality, leading to adverse health impacts including increased risk of premature mortality. A technically viable way to mitigate the health impacts of aviation is the use of desulfurized jet fuel, as has been done with road transportation in many jurisdictions. To attain levels of 15 ppm – a measure of the sulfur concentration in fuel – from the current average levels of 400-800 ppm would increase the cost of jet fuel by 1.6-6.6 ¢/gal, i.e. an increase in the cost of a gallon of just over 1% at 2011 prices.
Although the environmental implications are complex, the MIT-led research indicates transitioning to an ultra-low sulfur jet fuel is likely to prevent 1000-4000 premature mortalities per year (if implemented globally), but may increase globally averaged climate warming caused by aviation by 1-8%.
Commercial aviation fuel (Jet A/A-1) contains sulfur at concentrations of 400-800 ppm, although there is significant variation. By contrast, US road transportation fuel is subject to an ultra-low sulfur fuel standard of 15 ppm, which is about 97% less than jet fuel. Other jurisdictions including Australia, Canada, New Zealand, Mexico, Japan, India, Argentina, Brazil, Chile, Peru and the European Union have instituted similar standards for road transportation. Marine fuels are being subjected to increasingly stringent standards too, but marine bunker fuels have higher sulfur content than aviation or road transportation fuels.
Sulfur in fuel results in the emission of SOx (sulfur oxides) upon combustion. SOx is predominantly a gas when emitted, but gets converted in the atmosphere to a form of fine particulate matter (i.e. small particles) called sulfate. Sulfate particles predominantly scatter solar radiation, some of it back into space, therefore offsetting a fraction of global warming, although whether this is climatically beneficial or not is a subject of continuing research. A second important effect of SOx emissions is to increase the amount of fine particles that people inhale. There has been substantial quantitative evidence collected over decades that links human exposure to fine particulate matter to an increased risk of premature mortality and other adverse health effects. Finally, SOx emissions result in acid rain and associated damages.
Jet fuel can be desulfurized in the same way as road transportation fuels. Jet fuel is chemically very similar to diesel and there are no significant technical challenges in doing this, although a corrosion inhibitor/lubricity improver (CI/LI) may need to be added to the resultant fuel in order to prevent excessive component wear within engine fuel pumps. This is done routinely in the military and the cost is negligible compared to the cost of desulfurization. This hydrodesulfurization process will increase the cost of fuel by just over 1% at present-day prices, which maps to an industry total $1.3-3.8bn per year (in 2006 US$) if implemented globally, or $0.5-1.4bn per year for the US alone.
The dominant adverse environmental result of desulfurization is that removing sulfur from fuel results in increased CO2 emissions because hydrodesulfurization involves the release of relatively small amounts of CO2 and consumes additional energy. A second potentially adverse effect is that the reflection of solar radiation into space by sulfate particles would be reduced. In combination, these are estimated to increase the globally-averaged climate warming caused by the production and use of a gallon of jet fuel by 1-8% if it is desulfurized.
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