The diminishing importance of nitrogen dioxide emissions from road vehicle exhaust

TY - JOUR

T1 - The diminishing importance of nitrogen dioxide emissions from road vehicle exhaust

AU - Carslaw, David C.

AU - Farren, Naomi J.

AU - Vaughan, Adam R.

AU - Drysdale, William S.

AU - Young, Stuart

AU - Lee, James D.

N1 - ©2018 The Author(s).

PY - 2019/1/1

Y1 - 2019/1/1

N2 - The direct emission of nitrogen dioxide (NO2) from road vehicle exhaust has been an important contributor to near-road ambient concentrations of NO2 in many European cities. Diesel vehicles and their use of emission control technologies such as Diesel Oxidation Catalysts, have dominated the emission of NO2 from road vehicles. In this work, we summarise findings from recent vehicle emission remote sensing measurements in the UK that provide detailed information on the emissions of NO2 and total NOx(NO2 + NO). We show that while new diesel cars and light commercial vehicles are associated with high (typically 30%) proportions of NO2/NOx, the amount of absolute NOx and NO2 emitted by most Euro 6 vehicles has decreased substantially and that absolute emissions of NO2 have been reducing since around 2007. Additionally, we find that the amount of NO2 decreases as the vehicle mileage increases. Taken together, these factors have led to substantial reductions in emissions of NO2 in recent years from light duty diesel vehicles, which has contributed to reduced roadside NO2 concentrations. There is a need however for commonly used emission factor models to account for these changes in emissions of NO2.

AB - The direct emission of nitrogen dioxide (NO2) from road vehicle exhaust has been an important contributor to near-road ambient concentrations of NO2 in many European cities. Diesel vehicles and their use of emission control technologies such as Diesel Oxidation Catalysts, have dominated the emission of NO2 from road vehicles. In this work, we summarise findings from recent vehicle emission remote sensing measurements in the UK that provide detailed information on the emissions of NO2 and total NOx(NO2 + NO). We show that while new diesel cars and light commercial vehicles are associated with high (typically 30%) proportions of NO2/NOx, the amount of absolute NOx and NO2 emitted by most Euro 6 vehicles has decreased substantially and that absolute emissions of NO2 have been reducing since around 2007. Additionally, we find that the amount of NO2 decreases as the vehicle mileage increases. Taken together, these factors have led to substantial reductions in emissions of NO2 in recent years from light duty diesel vehicles, which has contributed to reduced roadside NO2 concentrations. There is a need however for commonly used emission factor models to account for these changes in emissions of NO2.

KW - Euro standards

KW - Remote sensing

KW - Urban air pollution

KW - Vehicle emissions

UR - http://www.scopus.com/inward/record.url?scp=85059746126&partnerID=8YFLogxK

U2 - 10.1016/j.aeaoa.2018.100002

DO - 10.1016/j.aeaoa.2018.100002

M3 - Article

AN - SCOPUS:85059746126

SN - 2590-1621

VL - 1

JO - Atmospheric Environment: X

JF - Atmospheric Environment: X

M1 - 100002

ER -