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Air Pollution Tops Other Sources of Contamination in Tampa Bay

More than half the nitrogen entering Tampa Bay is coming from air pollution, primarily from cars and power plants, according to important research conducted by a regional team of scientists.

The recently completed research, called the Bay Region Atmospheric Chemistry Experiment (BRACE), compiles data from a landmark multi-year study that involved scientists from the U.S. Environmental Protection Agency, the University of South Florida, the Tampa Bay Estuary Program and other federal, state and local environmental agencies.

The research quantified the sources and relative contributions of air pollution, also known as atmospheric deposition, to Tampa Bay. It also examined the potential effects of existing and proposed air quality regulations on nitrogen loadings to Tampa Bay.

“It’s a very complex study,” said Lindsay Cross, environmental science and policy manager for the estuary program. “Atmospheric deposition comes from a wide variety of sources — including cars, power plants, fertilizer plants, airplanes, agricultural operations, lawn mowers, and even lightning. Determining where it comes from and how it gets to Tampa Bay was like a giant chemistry experiment.”

Overall, power plants and industries are responsible for the bulk of the air emissions in our area because they release emissions from tall stacks that travel great distances. However, emissions from automobiles and trucks have a larger impact locally, because those emissions are generated low to the ground. “Local mobile sources – including cars and trucks — have a disproportionate impact because they’re generated closer to the ground and are less likely to be carried out of the watershed by wind,” Cross said.

Additionally, Cross said, a large portion of our air pollution comes from outside the Tampa Bay area, from an “airshed” that stretches north to Atlanta and south to Cuba.

Along with identifying the impact of automobile emissions, key findings from BRACE include:

  • Atmospheric sources now account for four times as much nitrogen loading to Tampa Bay as discharges from municipal sewage treatment plants and industry combined.
  • About 17% of the nitrogen loading to Tampa Bay comes from direct deposition on the bay itself, while 40% comes from air pollution that falls on the watershed and is washed to the bay in stormwater.
  • Two-thirds of the nitrogen deposition is contained in dust particles; one-third comes with rainfall.

Local and national regulations already are resulting in cleaner air. For example, local power plant upgrades, including replacing coal-burning plants with natural gas facilities and installing nitrogen reduction equipment on smoke stacks, resulted in a 95-ton per year decline in nitrogen between 2002 and 2012.

If fully implemented by 2020, the federal Clean Air Interstate Rule — requiring 27 Eastern states to reduce pollution from both mobile and stationary sources — could bring about a 24% reduction in nitrogen deposition to Tampa Bay. And new federal standards for automobile fuel efficiency will lead to cleaner cars on our roadways in coming years.

Individuals play an important role in improving our air and water quality. How we drive, what we drive and how much we drive all impact our environment and our wallet. Getting out of our cars is becoming easier, as regional transit options are expanded through ridesharing, designated bicycle lanes, and improved bus rapid transit. Many of these initiatives are led by the Tampa Bay Area Regional Transit Authority (TBARTA).

“There is a lot more discussion among elected officials and business leaders about transportation, from both an economic development perspective as well as the environmental issue,” said Amy Ellis, TBARTA communications director. “Any of the alternatives to driving alone in a car is going to help reduce emissions that end up in Tampa Bay.”

Learn more:,
the Tampa Bay Estuary Program’s citizen report on atmospheric deposition for online ride-matching of carpoolers and bikers – plus the “guaranteed ride home” for emergencies for more information about electric car charging stations in the region, an earlier cover story about the BRACE report on atmospheric deposition