Satellite-observed US power plant NOx emission reductions and their impact on air quality

Nitrogen oxide (NOx) emissions resulting from fossil fuel combustion lead to unhealthy levels of near-surface ozone (O-3). One of the largest U. S. sources, electric power generation, represented about 25% of the U. S. anthropogenic NOx emissions in 1999. Here we show that space-based instruments observed declining regional NOx levels between 1999 and 2005 in response to the recent implementation of pollution controls by utility companies in the eastern U. S. Satellite-retrieved summertime nitrogen dioxide (NO2) columns and bottom-up emission estimates show larger decreases in the Ohio River Valley, where power plants dominate NOx emissions, than in the northeast U. S. urban corridor. Model simulations predict lower O-3 across much of the eastern U. S. in response to these emission reductions.