Characterisation of nanoparticle emissions and exposure at traffic intersections through fast–response mobile and sequential measurements

New directions: Air pollution challenges for developing megacities like Delhi

“…Studies have shown in excess of a 20-fold increase in particle number concentrations at traffic lights during decelerating, accelerating or idling conditions compared with free flowing traffic conditions (Goel and Kumar, 2015). Traffic related line-sources also convert to intense point sources on roads where the delay time is usually measured in minutes.…”

Zone of influence for particle number concentrations at signalised traffic intersections

“…This is currently unknown whether the similar increase in PNCs can be expected within a ZoI of a TI. Our recent work suggested up to 29-times higher PNCs at TIs than those found on the rest of the route during free-flow traffic conditions (Goel and Kumar, 2015). This indicates much higher PNCs at different types of TIs but what is the ZoI under different driving conditions is yet poorly understood -this is one of the aims of this study.…”

“…Moreover, most of past studies are carried out at fixed sites at a point near a TI that made it challenging to capture the on-road profile of PNCs on intersecting roads and at longitudinal distances from the centre of TIs. A number of studies have also carried out mobile monitoring of nanoparticles within the vehicles (Goel and Kumar, 2015;Hudda et al, 2011;Joodatnia et al, 2013a, b;Knibbs et al, 2010;Zhu et al, 2007), but studies focusing on the on-road profiles of PNCs around TIs are still scarce and covered as a part of this study.…”

“…exposure to peak PNCs averaged over short durations such as 1 s averaged PNC) at the TIs contribute disproportionately higher exposure compared with those experienced at the rest of a commuting route with free-flow traffic conditions. For instance, our recent work found that as little as about 2% of commuting time spent in car at TIs can contribute up to about 25% of commuting exposure (Goel and Kumar, 2015).…”

“…Such equations could be useful for developing dispersion models for nanoparticles at TIs. Fourthly, this is the first time when positive matrix Cite this article as: Goel, A., Kumar, P., 2015 factorisation (PMF) has been applied to quantify the contribution of PNCs towards the total PNCs released during deceleration, acceleration, cruising and creep-idling at different types of TIs, as defined in Table 2. Such a quantification is useful to plan mitigation strategies to limit emissions and exposure to PNCs at pollution hotspots.…”