Substantial traffic emissions contribution to the global H 2 S budget

One year of hydrogen sulfide measurements in an urban traffic site were used to assess the importance of traffic in the overall high ambient air burden of H 2 S (mean annual concentration of 8 μg/m3). During calm nighttime hours, hourly values of H 2 S were correlated positively with those of CO (R 2 = 0.75) and SO 2 (R 2 = 0.70), suggesting a common source from traffic. For the driving conditions of the measurement site, H 2 S automotive emissions are around 24% w/w those of SO 2 , while European inventories calculate these at only 2.5%. H 2 S annual traffic emissions, based on the existing emission inventories for CO and SO 2 are calculated at 0.199–0.311 × 10 −3 Tg a −1 for Thessaloniki and are extrapolated to 0.030–0.0485 Tg a −1 for the EU15 countries and 2.6 Tg a −1 for Europe and Eurasia. It appears that traffic emissions make up a significant contribution to the global H 2 S budget.