Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 18, 3563-3587, 2018
https://doi.org/10.5194/acp-18-3563-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
12 Mar 2018
Analysis of the distributions of hourly NO2 concentrations contributing to annual average NO2 concentrations across the European monitoring network between 2000 and 2014
Christopher S. Malley1, Erika von Schneidemesser2, Sarah Moller3, Christine F. Braban4, W. Kevin Hicks1, and Mathew R. Heal5 1Stockholm Environment Institute, Environment Department, University of York, York, UK
2Institute for Advanced Sustainability Studies, Potsdam, Germany
3National Centre for Atmospheric Science (NCAS), Department of Chemistry, University of York, York, UK
4NERC Centre for Ecology & Hydrology, Penicuik, UK
5School of Chemistry, University of Edinburgh, Edinburgh, UK
Abstract. Exposure to nitrogen dioxide (NO2) is associated with negative human health effects, both for short-term peak concentrations and from long-term exposure to a wider range of NO2 concentrations. For the latter, the European Union has established an air quality limit value of 40 µg m−3 as an annual average. However, factors such as proximity and strength of local emissions, atmospheric chemistry, and meteorological conditions mean that there is substantial variation in the hourly NO2 concentrations contributing to an annual average concentration. The aim of this analysis was to quantify the nature of this variation at thousands of monitoring sites across Europe through the calculation of a standard set of chemical climatology statistics. Specifically, at each monitoring site that satisfied data capture criteria for inclusion in this analysis, annual NO2 concentrations, as well as the percentage contribution from each month, hour of the day, and hourly NO2 concentrations divided into 5 µg m−3 bins were calculated.

Across Europe, 2010–2014 average annual NO2 concentrations (NO2AA) exceeded the annual NO2 limit value at 8 % of > 2500 monitoring sites. The application of this chemical climatology approach showed that sites with distinct monthly, hour of day, and hourly NO2 concentration bin contributions to NO2AA were not grouped into specific regions of Europe, furthermore, within relatively small geographic regions there were sites with similar NO2AA, but with differences in these contributions. Specifically, at sites with highest NO2AA, there were generally similar contributions from across the year, but there were also differences in the contribution of peak vs. moderate hourly NO2 concentrations to NO2AA, and from different hours across the day. Trends between 2000 and 2014 for 259 sites indicate that, in general, the contribution to NO2AA from winter months has increased, as has the contribution from the rush-hour periods of the day, while the contribution from peak hourly NO2 concentrations has decreased. The variety of monthly, hour of day and hourly NO2 concentration bin contributions to NO2AA, across cities, countries and regions of Europe indicate that within relatively small geographic areas different interactions between emissions, atmospheric chemistry and meteorology produce variation in NO2AA and the conditions that produce it. Therefore, measures implemented to reduce NO2AA in one location may not be as effective in others. The development of strategies to reduce NO2AA for an area should therefore consider (i) the variation in monthly, hour of day, and hourly NO2 concentration bin contributions to NO2AA within that area; and (ii) how specific mitigation actions will affect variability in hourly NO2 concentrations.

Citation: Malley, C. S., von Schneidemesser, E., Moller, S., Braban, C. F., Hicks, W. K., and Heal, M. R.: Analysis of the distributions of hourly NO2 concentrations contributing to annual average NO2 concentrations across the European monitoring network between 2000 and 2014, Atmos. Chem. Phys., 18, 3563-3587, https://doi.org/10.5194/acp-18-3563-2018, 2018.
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This study quantifies the contribution of hourly nitrogen dioxide (NO2) variation to annual NO2 concentrations at > 2500 sites across Europe. Sites with distinct monthly, hour of day, and hourly NO2 contributions to annual NO2 were not grouped into specific European regions. Within relatively small areas there were sites with similar annual NO2 but with differences in these contributions. Therefore, measures implemented to reduce annual NO2 in one location may not be as effective in others.
This study quantifies the contribution of hourly nitrogen dioxide (NO2) variation to annual NO2...
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