Commercial ships spew half as much particulate pollution as wo...( Globally commercial ships emit almos...)

Globally, commercial ships emit almost half as much particulate pollution into the air as the total amount released by cars, according to a new study. Ship pollutants affect both the Earth's climate and the health of people living along coastlines.

The study is the first to provide a global estimate of maritime shipping's total contribution to air particle pollution based on direct measurements of emissions. The authors estimate that worldwide, ships emit 0.9 teragrams, or about 2.2 million pounds, of particulate pollution each year. Shipping also contributes almost 30 percent of smog-forming nitrogen oxide gases.

"Since more than 70 percent of shipping traffic takes place within 250 miles of the coastline, this is a significant health concern for coastal communities," says lead author Daniel Lack, a researcher at the National Oceanic and Atmospheric Administration (NOAA)'s Earth System Research Laboratory in Boulder, Colorado. He and his colleagues reported their findings on 25 February 2009 in the Journal of Geophysical Research Atmospheres, a publication of the American Geophysical Union (AGU).

Earlier research by one of the study's authors, James Corbett, of the University of Delaware, in Newark, linked particulate pollution to premature deaths among coastal populations.

Commercial ships emit both particulate pollution and carbon dioxide. Carbon dioxide from ships makes up roughly three percent of all human-caused emissions of the gas. But particulate pollution and carbon dioxide have opposite effects on climate. The particles have a global cooling effect at least five times greater than the global warming effect from ships' carbon dioxide emissions, Lack says.

Lack is also with the Boulder-based Cooperative Institute for Research in Environmental Sciences, which is jointly supported by NOAA and the University of Colorado, Boulder.

During the summer of 2006, Lack and colleagues, aboard the N
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