title: Did policies to abate atmospheric emissions from traffic have a positive effect in London?
abstract: A large number of policy initiatives are being taken at the European level, across the United Kingdom and in London to improve air quality and reduce population exposure to harmful pollutants from traffic emissions. Trends in roadside increments of nitrogen oxides (NOX), nitrogen dioxide (NO2), particulate matter (PM), black carbon (CBLK) and carbon dioxide (CO2) were examined at 65 London monitoring sites for two periods of time: 2005-2009 and 2010-2014. Between 2005 and 2009 there was an overall increase in NO2reflecting the growing evidence of real world emissions from diesel vehicles. Conversely, NO2decreased by 10%·year-1from 2010 onwards along with PM2.5(-28%·year-1) and black carbon (-11%·year-1). Downwards trends in air pollutants were not fully explained by changes in traffic counts therefore traffic exhaust emission abatement policies were proved to be successful in some locations. PM10concentrations showed no significant overall change suggesting an increase in coarse particles which offset the decrease in tailpipe emissions; this was especially the case on roads in outer London where an increase in the number of Heavy Good Vehicles (HGVs) was seen. The majority of roads with increasing NOXexperienced an increase in buses and coaches. Changes in CO2from 2010 onwards did not match the downward predictions from reduced traffic flows and improved fleet efficiency. CO2increased along with increasing HGVs and buses. Polices to manage air pollution provided differential benefits across London's road network. To investigate this, k-means clustering technique was applied to group roads which behaved similarly in terms of trends to evaluate the effectiveness of policies to mitigate traffic emissions. This is the first time that London's roadside monitoring sites have been considered as a population rather than summarized as a mean behaviour only, allowing greater insight into the differential changes in air pollution abatement policies.
authors.affiliation: Environmental Research Group, MRC PHE Centre for Environment and Health, King's College London, London, SE1 9NH, United Kingdom. Electronic address: anna.font_font@kcl.ac.uk.
authors.forename: Anna
authors.initials: A
authors.lastname: Font
authors.affiliation: Environmental Research Group, MRC PHE Centre for Environment and Health, King's College London, London, SE1 9NH, United Kingdom.
authors.forename: Gary W
authors.initials: GW
authors.lastname: Fuller
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000032:analysis / Q000331:legislation & jurisprudence*; D002245:Carbon Dioxide / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods; D058735:Environmental Policy; D008131:London; D018986:Motor Vehicles; D009585:Nitrogen Dioxide / Q000032:analysis; D009589:Nitrogen Oxides / Q000032:analysis; D052638:Particulate Matter / Q000032:analysis; D053260:Soot / Q000032:analysis; D006113:United Kingdom; D001335:Vehicle Emissions / Q000032:analysis / Q000331:legislation & jurisprudence*
chemical_list: D000393:Air Pollutants; D009589:Nitrogen Oxides; D052638:Particulate Matter; D053260:Soot; D001335:Vehicle Emissions; D002245:Carbon Dioxide; D009585:Nitrogen Dioxide
keywords: Exhaust emissions; London; Non-exhaust emissions; Traffic; Trends