The findings, published in the journal Environmental Pollution, showed significant variability across the city with some roads showing significant decreases but others did not improve. Examples include the notable improvement in nitrogen dioxide alongside Putney High Street and the deterioration along Upper Thames Street; the improvements in airborne particles on Marylebone Road in central London contrasting with the increase in coarse particles alongside some busy roads in outer London including Westhorne Avenue, part of the south circular in Eltham.
Between 2005 and 2009 nitrogen dioxide (NO2) alongside London's roads increased by an average of 11 per cent per year. This can be attributed in part to a three per cent rise in the number of diesel buses and coaches between 2005 and 2009 and to the failure of tighter Euro class emissions standards. This concurs with the growing body of evidence suggesting that real-world emissions from diesel vehicles did not align with their performance in factory tests.
After 2010, most roads showed some improvement in NO2 with an average decrease of five per cent per year. Fitting new exhaust clean-up technology to older buses also helped to curb nitrogen dioxide along some of London's roads. Putney High Street, for example, saw a particular improvement with a significant reduction in NO2 levels after 2010, thanks largely to the retrofitting of older buses technology to cut emissions. Nevertheless, around three-quarters of air quality monitoring sites still recorded levels exceeding the NO2 EU Limit Value in 2015.
Read the full article @ Phys.Org