Long-term trends of primary and secondary NO2 production in the Athens area. Variation of the NO2/NOx ratio

Mavroidis, I; Chaloulakou, A

dc.contributor.author	Mavroidis, I	en
dc.contributor.author	Chaloulakou, A	en
dc.date.accessioned	2014-03-01T01:35:57Z
dc.date.available	2014-03-01T01:35:57Z
dc.date.issued	2011	en
dc.identifier.issn	1352-2310	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/21260
dc.subject	Diesel exhaust after-treatment	en
dc.subject	NO2 air quality standards	en
dc.subject	NO2/NOx ratio	en
dc.subject	NOx emissions reduction	en
dc.subject	Photochemical oxidant	en
dc.subject	Primary NO2	en
dc.subject	Traffic-related air pollutants	en
dc.subject.classification	Environmental Sciences	en
dc.subject.classification	Meteorology & Atmospheric Sciences	en
dc.subject.other	Diesel exhausts	en
dc.subject.other	NOx Emissions	en
dc.subject.other	Photochemical oxidants	en
dc.subject.other	Primary NO	en
dc.subject.other	Traffic-related	en
dc.subject.other	Air quality	en
dc.subject.other	Air quality standards	en
dc.subject.other	Automobiles	en
dc.subject.other	Concentration (process)	en
dc.subject.other	Emission control	en
dc.subject.other	Ozone	en
dc.subject.other	Photochemical reactions	en
dc.subject.other	Pollution	en
dc.subject.other	Time series	en
dc.subject.other	Nitrogen oxides	en
dc.subject.other	nitric oxide	en
dc.subject.other	nitrogen oxide	en
dc.subject.other	ozone	en
dc.subject.other	air quality	en
dc.subject.other	atmospheric pollution	en
dc.subject.other	diesel	en
dc.subject.other	emission inventory	en
dc.subject.other	long range transport	en
dc.subject.other	net ecosystem production	en
dc.subject.other	nitrous oxide	en
dc.subject.other	oxidant	en
dc.subject.other	photochemistry	en
dc.subject.other	pollutant transport	en
dc.subject.other	spatiotemporal analysis	en
dc.subject.other	standard (regulation)	en
dc.subject.other	time series	en
dc.subject.other	traffic emission	en
dc.subject.other	urban area	en
dc.subject.other	urban atmosphere	en
dc.subject.other	air monitoring	en
dc.subject.other	air pollutant	en
dc.subject.other	air quality standard	en
dc.subject.other	article	en
dc.subject.other	atmosphere	en
dc.subject.other	catalyst	en
dc.subject.other	concentration (parameters)	en
dc.subject.other	diesel engine	en
dc.subject.other	exhaust gas	en
dc.subject.other	filter	en
dc.subject.other	Greece	en
dc.subject.other	oxidation	en
dc.subject.other	photochemistry	en
dc.subject.other	priority journal	en
dc.subject.other	season	en
dc.subject.other	time series analysis	en
dc.subject.other	urban area	en
dc.subject.other	Athens [Attica]	en
dc.subject.other	Attica	en
dc.subject.other	Greece	en
dc.title	Long-term trends of primary and secondary NO2 production in the Athens area. Variation of the NO2/NOx ratio	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.atmosenv.2010.11.006	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.atmosenv.2010.11.006	en
heal.language	English	en
heal.publicationDate	2011	en
heal.abstract	This paper examines the contribution of primary and secondary NO2 production in NOx concentrations and offers a comprehensive analysis of the long-term trends of NOx, NO2 and O-3 concentrations, as well as of the NO2/NOx ratio, in the Athens urban conurbation. Long-term pollutant concentration time series show that NO2 concentrations in Athens have decreased since 1987 but at a slower rate than those of NOx, resulting to an increasing NO2/NOx concentration ratio. However, this increasing trend is much smaller than those observed in urban areas of other European countries. The possible causes of this trend are examined and especially the interaction with ozone and the amount of direct NO2 traffic emissions. The results indicate that the increasing NO2/NOx ratio in the Athens area is mainly attributable to an increased secondary formation of NO2 through photochemical reactions in the atmosphere. More specifically, two different empirical methodologies were applied to examine the primary NO2 concentration fraction in Athens, using ambient monitoring data from a kerbside station. Both methods indicate that the primary NO2 concentration share has not altered significantly between 1998 and 2006. This is mainly attributed to the fact that in the Athens area diesel passenger cars are not allowed and after-treatment technologies such as particle filters and oxidation catalysts are not yet applied in Greece. A probable future penetration of diesel passenger cars in Athens should be combined with inventories of primary NO2 emissions and with the development of appropriate policies to reduce ambient NO2 concentrations below the EU limit values. (C) 2010 Elsevier Ltd. All rights reserved.	en
heal.publisher	PERGAMON-ELSEVIER SCIENCE LTD	en
heal.journalName	Atmospheric Environment	en
dc.identifier.doi	10.1016/j.atmosenv.2010.11.006	en
dc.identifier.isi	ISI:000297488900005	en
dc.identifier.volume	45	en
dc.identifier.issue	38	en
dc.identifier.spage	6872	en
dc.identifier.epage	6879	en