Atmospheric scientists recognize the long-distance transport of air pollutants. When we used leaded gasoline, we saw elevated levels of airborne lead in cities, but also in the Greenland ice pack, thousands of miles away. And past shutdowns of coal-fired power plants in the Midwest resulted in lower nitric oxide concentrations in the eastern U.S.
New studies show that emissions of ammonia and other air pollutants from agriculture are carried by winds to states far removed from our agricultural heartland. Ammonia is released in the use of nitrogen fertilizer and as a result of the decomposition of manure from barnyard animals.
In the atmosphere, ammonia reacts with nitric oxide, sulfur dioxide, and other industrial pollutants to form small particles, known as aerosols. These are often less than 2.5 microns in diameter, so easily inhaled by humans. A variety of studies have linked small particle exposure to respiratory and cardiovascular disease.
The new study compares the value of agricultural exports from the U.S. to the estimated health care costs in states downwind from Midwestern growers. The comparison is not pretty. Higher health care costs exceed the net export value of food crops from the U.S. Moreover, the distribution of costs and benefits is uneven. The farmland states of the Great Plains reap most of the benefits of agriculture, whereas northeastern states pay for most of the incremental health care.
We should support regional regulatory policies on agricultural air pollutants to reduce the costs to our society and spread them more evenly across regions of source and sink.
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Web Links
See Paulot and Jacob (2014). Hidden cost of U.S. agricultural exports: Particulate matter from ammonia emissions. Environmental Science and Technology.
Photo, taken on June 5, 2012, courtesy of Artur Staszewski via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio. Support for Earth Wise comes from the Cary Institute of Ecosystem Studies in Millbrook, NY.