Combustion-generated carbonaceous urban atmospheric UFPs: Fuel optimisation in transport and decentralized electricity economies to minimise their production and impact
34% carbonaceous ultrafine particles (UFPs) in the atmosphere come from road transport . Their toxicity generally increases as the particle size decreases. They are found in urban atmospheres worldwide  and aggregate to form larger assemblies. Dobbins concluded from TEM that flames and diesel engines generated nascent single nanoparticles (NPs) (2<d<10nm; 1.8< C/H <2.2) that were precursors to carbonaceous fractal chain aggregates (5< C/H <10) and nanotubes , both with PAHs adsorbed thereon . Lawther saw a relationship between air pollution and the incidence of bronchitis  and heart risks rise 38% for women who live within 49m of busy roads . Nano-organic carbon (NOC) particles and hydrophobic soot NPs are emitted more from diesel- than gasoline-fuelled vehicles (i.e. the ratio of soot:NOC rises from 0.5 (gasoline engines) to 3.0 (diesel engines)). Here we describe the minimisation of carbonaceous UFP and CO2 emission from generator and vehicle engines (using H2-O2injectants and modified fuels (i.e. bio-esters in gasoline engines or water-in-biodiesel emulsions in diesel engines (see Figure 1))) and describe control of their primary particle size/fractality/PAH passenger load/hydrophobicity/toxicity/impact. Carbon is of the seven elements that have changed the world ; this work is focussed on making its nanoparticle impact (as we transition to a zero-carbon future) only positive.
Fig.1 TEM micrographs of diesel emitted carbonaceous UFP particles with various tested fuels at 75% load: (a) diesel and (b) water-in-biodiesel emulsion (scale bars = 100nm). (c) Formation of DEPs is lower in Span 80 stabilised water-in-diesel/biodiesel emulsions at all loads.
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