title: Study of the uncertainty in NO2 chemiluminescence measurements due to the NO-O3 reaction in sampling lines.
abstract: BACKGROUND
  The change in light intensity that takes place when an ambient air sample is drawn into the detection chamber of a chemiluminescence monitor generates changes in the concentrations of several species, such as NO(2), NO and O(3). Although this phenomenon has been known for several decades, there is still no commonly accepted approach on when or how to correct for it in NO(2) and O(3) readings.
  
  
  CONCLUSIONS
  In this work, we have assessed the expanded uncertainty of two chemiluminescence NO( x ) analysers commercially available according to EN 14211:2005, with the aim of establishing the maximum allowable standard uncertainty due to the reaction between NO and O(3) in the sampling system.
  
  
  CONCLUSIONS
  Although this maximum allowable uncertainty cannot be a universal value-as it will depend on the performance of each analyser-our results have led us to propose the conservative value of 2%. We have also proposed a methodology for improving data quality which could be easily implemented by those responsible for air quality data validation.
authors.affiliation: Department of Chemical Engineering, School of Chemistry, University of Murcia, 30071, Murcia, Spain. mdoval@um.es
authors.forename: Marta Doval
authors.initials: MD
authors.lastname: Miñarro
authors.forename: Enrique González
authors.initials: EG
authors.lastname: Ferradás
authors.forename: Jonathan Barberá
authors.initials: JB
authors.lastname: Rico
authors.forename: Fernando Díaz
authors.initials: FD
authors.lastname: Alonso
authors.forename: Francisco J Marzal
authors.initials: FJ
authors.lastname: Martínez
authors.forename: Cristina Romero
authors.initials: CR
authors.lastname: Trigueros
mesh_terms: D000393:Air Pollutants / Q000032:analysis / Q000737:chemistry* / Q000592:standards; D000397:Air Pollution / Q000706:statistics & numerical data; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods; D008163:Luminescent Measurements / Q000295:instrumentation / Q000379:methods*; D009569:Nitric Oxide / Q000032:analysis / Q000737:chemistry* / Q000592:standards; D009585:Nitrogen Dioxide / Q000032:analysis / Q000737:chemistry* / Q000592:standards; D010126:Ozone / Q000032:analysis / Q000737:chemistry* / Q000592:standards; D035501:Uncertainty
chemical_list: D000393:Air Pollutants; D009569:Nitric Oxide; D010126:Ozone; D009585:Nitrogen Dioxide
references.citation: Analyst. 1975 Jul;100(1192):449-64
references.pmid: 1094862
references.citation: J Environ Monit. 2003 Aug;5(4):529-40
references.pmid: 12948223
references.citation: Environ Int. 2005 Apr;31(3):445-67
references.pmid: 15734196