20 August 2004

Invasion of the Eastern Blob

Forrest M. Mims III

Last week I was in a jet that had to punch through a thick layer of murky haze as it left San Antonio, Texas, on the way to Atlanta, Georgia, and Baltimore, Maryland.

The ground between San Antonio and Baltimore was obscured by a thick layer of murky haze.

The purpose of the trip was to speak about citizen science at NASA's Goddard Space Flight Center. After the talk, Brent Holben, director of the AERONET network of robotic sun photometers, took me to a roof to see his sunlight instruments. The haze was so thick we spent as much time looking at it as we did the instruments.

This haze is what I have named the Eastern Blob. It's a chemical soup of air pollution that persistently blankets much of the Eastern US. Much, perhaps most, is caused by the huge coal-burning power plants of the Ohio Valley and the Federal government's Tennessee Valley Authority. The rest comes from agriculture fires, automobile exhaust, factories and vegetation.

Coal contains sulfur, mercury, lead and a host of other noxious materials. Power plants that burn coal release this stuff into the atmosphere.

The sulfur becomes tiny sulfate particles that form a thick blanket of haze. The burning process also forms nitrogen dioxide, which forms ozone in the presence of sunlight.

When these emissions drift over clean areas hundreds of kilometers away, their air is immediately polluted. They then come under the Federal Clean Air Act and are held to the same standards as the regions that emitted the pollution in the first place. Local regulators tell people to stop fueling cars and mowing lawns, steps that have only a trivial impact on ozone.

Coal is cheap and plentiful. Cleaning up coal-burning power plants is very costly. Yet huge benefits will occur when coal-burning power plants are modernized.

This was dramatically proved during the August 2003 electrical blackout across the North Eastern United States. Scientists from the University of Maryland flew a plane equipped with air sampling instruments across areas affected by the blackout. They found that ozone was reduced by an astonishing 38 parts per billion. Visibility was increased by more than 40 km.

Dr. Lackson Marufu led this important experiment. In a recent paper published in Geophysical Research Letters, Marufu and his co-authors concluded that "... emissions from power plants hundreds of kilometers upwind play a dominant role in regional haze and ozone production." (See Lackson T. Marufu, et al., in The 2003 North American electrical blackout: An accidental experiment in atmospheric chemistry, Geophysical Research Letters 31, L13106, doi:10.1029/2004GL019771,15 July 2004.)

These results were completely unexpected by air quality regulators, who must now try to learn why their models and data have misled them and the rest of us.

Forrest M. Mims III and his science are featured online at http://www.forrestmims.org/.

This feature was originally published in Forrest Mims's weekly science column in the Seguin Gazette-Enterprise, Seguin, Texas. The column is written for a general audience.