Observation-Based Assessment of the Impact of Nitrogen Oxides Emissions Reductions on Ozone Air Quality over the Eastern United States
- 1 July 2007
- journal article
- Published by American Meteorological Society in Journal of Applied Meteorology and Climatology
- Vol. 46 (7), 994-1008
- https://doi.org/10.1175/jam2523.1
Abstract
Ozone is produced by chemical interactions involving nitrogen oxides (NOx) and volatile organic compounds in the presence of sunlight. At high concentrations, ground-level ozone has been shown to be harmful to human health and to the environment. It has been recognized that ozone is a regional-scale problem and that regionwide control strategies would be needed to improve ozone air quality in the eastern United States. To mitigate interstate transport of ozone and its precursors, the U.S. Environmental Protection Agency issued a regional rule in 1998 known as the “NOx State Implementation Plan (SIP) Call,” requiring 21 states in the eastern United States to reduce their summertime NOx emissions by 30 May 2004. In this paper, the effectiveness of the new emission control measures mandated by the NOx SIP Call is assessed by quantifying the changes that occurred in the daily maximum 8-h ozone concentrations measured at nearly 50 locations, most of which are rural (33 sites of the Clean Air Status and Trend Network and 16 sites of the Air Quality System), over the eastern United States. Given the strong dependence of ozone formation and accumulation on meteorological conditions, the incidence of the latter is first mitigated, and meteorologically adjusted ozone concentrations are extracted using a multiple regression technique. By examining the differences between the cumulative distribution functions of the meteorologically adjusted ozone concentrations, it is shown that ozone concentrations in the eastern United States are now on average 13% less than those prior to the NOx SIP Call. Using back-trajectory analyses, it is also shown that emission controls on the electricity-generating units located in the Ohio River Valley have contributed toward the improvement of ozone air quality in downwind regions, especially east and northeast of the Ohio River Valley.Keywords
This publication has 17 references indexed in Scilit:
- Long-term trends of primary and secondary pollutant concentrations in Switzerland and their response to emission controls and economic changesAtmospheric Environment, 2001
- Long-term changes of ozone and traffic in BilbaoAtmospheric Environment, 2001
- Interpreting the Information in Ozone Observations and Model Predictions Relevant to Regulatory Policies in the Eastern United StatesBulletin of the American Meteorological Society, 2000
- A trajectory-clustering-correlation methodology for examining the long-range transport of air pollutantsAtmospheric Environment, 1998
- Evaluating the Effectiveness of Ozone Management Efforts in the Presence of Meteorological VariabilityJournal of the Air & Waste Management Association, 1998
- Moderating the Influence of Meteorological Conditions on Ambient Ozone ConcentrationsJournal of the Air & Waste Management Association, 1996
- On the Assessment of Ozone Control Policies for the Northeastern United StatesPublished by Springer Science and Business Media LLC ,1996
- Detecting and Tracking Changes in Ozone Air QualityAir & Waste, 1994
- Meteorologically adjusted ozone trends in urban areas: A probabilistic approachAtmospheric Environment. Part B. Urban Atmosphere, 1993
- A characterization of the spatiotemporal variability of non-urban ozone concentrations over the eastern United StatesAtmospheric Environment. Part A. General Topics, 1993