A comparative study on the ultrafine particle episodes induced by vehicle exhaust: A crude oil refinery and ship emissions

A study on the contribution of vehicle exhausts, ships and an oil refinery emission to the ambient air concentration of ultrafine particles (UFPs) is presented. It is based on a data set of particle number coarser than 2.5 nm (N), black carbon (BC), gaseous pollutants (NOx, SO2, CO and O3), PM2.5 and PM10 measured from 2008 to 2010 in the ambient air of Santa Cruz de Tenerife City, where a previous study found an association between hospitalizations due to heart failure and exposure to UFPs in the ambient air. The observed relationship between N, BC and gaseous pollutants allowed segregating UFP concentrations in a set of components linked to each source. It was found that vehicle exhausts contribute to the background of UFPs, whereas high UFP episodes were due to the emissions of the refinery and ships. The concentration of UFP linked to vehicle exhaust emissions maximized in the morning (07:00–09:00 GMT, 5000–25,000 cm− 3 = 25th–75th percentile), whereas those linked to ship (15,000–45,000 cm− 3) and refinery (25,000–95,000 cm− 3) emissions maximized in the 10:00–17:00 GMT period due to the effects of meteorology and photochemistry. It was found that the UFP concentrations were more sensitive to the fresh emissions of the three sources than PM2.5, which was mostly linked to aged fine particles (0.1–1 μm) of the urban background. BC was the better tracer of vehicle exhaust emissions. It was concluded that the simultaneous monitoring of UFP, BC and PM2.5 is a suitable strategy of tracing aerosol pollutants of different nature (fresh vs. aged) and from different sources.

Figure optionsDownload as PowerPoint slideHighlights
► Previous studies on urban ultrafine particles have focused on vehicle exhaust emissions.
► We found that downwind of oil refineries and ship emissions, vehicle exhaust results in moderate ultrafine particle concentrations.
► Ultrafine particles pollution episodes are induced by emission of oil refineries and ships.
► Ultrafine particles background is dominated by vehicle exhaust emissions.