English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Isocyanic acid (HNCO), an acidic gas found in tobacco smoke, urbanenvironments, and biomass-burning-affected regions, has been linked toadverse health outcomes. Gasoline- and diesel-powered engines and biomassburning are known to emit HNCO and hypothesized to emit precursors such asamides that can photochemically react to produce HNCO in the atmosphere.Increasingly, diesel engines in developed countries like the United Statesare required to use selective catalytic reduction (SCR) systems to reducetailpipe emissions of oxides of nitrogen. SCR chemistry is known to produceHNCO as an intermediate product, and SCR systems have been implicated as anatmospheric source of HNCO. In this work, we measure HNCO emissions from anSCR system-equipped diesel engine and, in combination with earlier data, usea three-dimensional chemical transport model (CTM) to simulate the ambientconcentrations and source/pathway contributions to HNCO in an urbanenvironment. Engine tests were conducted at three different engine loads,using two different fuels and at multiple operating points. HNCO was measuredusing an acetate chemical ionization mass spectrometer. The diesel engine wasfound to emit primary HNCO (3–90 mg kg fuel<sup>−1</sup>) but we did not findany evidence that the SCR system or other aftertreatment devices (i.e.,oxidation catalyst and particle filter) produced or enhanced HNCO emissions.The CTM predictions compared well with the only available observationaldatasets for HNCO in urban areas but underpredicted the contribution fromsecondary processes. The comparison implied that diesel-powered engines werethe largest source of HNCO in urban areas. The CTM also predicted thatdaily-averaged concentrations of HNCO reached a maximum of ∼ 110 pptvbut were an order of magnitude lower than the 1 ppbv level that could beassociated with physiological effects in humans. Precursor contributions fromother combustion sources (gasoline and biomass burning) and wintertimeconditions could enhance HNCO concentrations but need to be explored infuture work

Investigating diesel engines as an atmospheric source of isocyanic acid in urban areas