Agriculture top source of fine particulates — study

Source: Sean Reilly, E&E reporter • Posted: Tuesday, May 17, 2016

Farming operation emissions are now the single biggest human source of fine particulate pollution in much of the United States, Europe and China, researchers from Columbia University and NASA conclude in a new study.

In the United States, for example, food production contributes to as much man-made fine particulate pollution as all other human activities combined, according to the study published online today in Geophysical Research Letters. In China, livestock and fertilizer account for 45 percent of such pollution, while in Europe, the ratio is about 55 percent.

“At present, agricultural pollution dominates over wide areas in Europe, the central U.S. and in regions west of Beijing,” the study says.

The reason mainly lies in the form of ammonia, a nitrogen compound that ends up in the atmosphere as a gas resulting from livestock waste and fertilizer use. It then combines with nitrogen oxides and sulfates produced by coal-fired power plants and other sources to form the fine particulates that are no more than 2.5 micrometers in diameter — or one-thirtieth the size of a human hair — and are technically known as PM2.5, according to a news release from Columbia’s Earth Institute.

U.S. EPA links particulate pollution to a wide range of health effects, including early death in people with heart and lung disease, aggravated asthma, and irregular heartbeat.

But if fertilizer use is almost certain to continue growing to meet food production needs, the fact that farm-related emissions have to combine with other pollutants to create particulates is “good news,” Susanne Bauer, the study’s lead author, said in the release. Tighter limits on power plant releases and other factors meant farm emissions will eventually be “starved” of the industrial pollutants needed to create PM2.5, according to the release.

“Globally, almost all near-surface PM 2.5 in populated areas [will originate] from natural sources, such as desert dust and biomass burning, except for some industrial areas in Africa and northern India,” the study says.

While other studies have documented the contribution of agricultural releases to fine particulate formation, the new study is possibly the first to look at the worldwide impact and to forecast future trends, the news release said.