Observations of isocyanic acid in the marine boundary layer during the CalNex 2010 field campaign

Isocyanic acid (HNCO), a carcinogen present in cigarette smoke and industrial emissions, has recently been measured in the troposphere. Large uncertainties exist in ambient HNCO concentrations due to limited field measurements and limited understanding of the sources and fate of HNCO in the troposphere. Previous measurements indicate that HNCO mixing ratios may be elevated (>1ppb) in urban environments, posing significant health concerns. Here, we present ambient measurements of HNCO during the CalNex 2010 field study using a fast-response chemical ionization time-of-flight mass spectrometer. We discuss potential sources as well as the spatial and temporal distribution of HNCO in coastal California to comment on the impact of this gas-phase species in polluted marine regions.