Estimation of global vehicular methyl bromide emissions: Extrapolation from a case study in Santiago, Chile

Between June 1 and June 8, 1996, 144 whole air samples were collected in Santiago, Chile. The temporal and geographical enhancement of CH 3 Br correlated with incomplete combustion tracers emitted from vehicles during the morning commute. From these, a city‐wide CH 3 Br/CO volume emission ratio of 2.2 × 10 −6 was measured in ambient air. Without using the CO measurements, we estimate an annual release of 8.9 tons of CH 3 Br in Santiago based solely upon enhanced concentrations observed throughout the study area during the morning traffic period. This enhancement corresponds to 8.0 × 10 −6 kg CH 3 Br emitted for each liter of gasoline used (leaded and unleaded). By scaling the annual gasoline usage in Santiago to countries still using leaded gasoline, and assuming the above 8.0 × 10 −6 kg/L value holds true, a global vehicular CH 3 Br emission of 4 ± 3 Gg/year is calculated. This small vehicular CH 3 Br emission source strength will not improve the current CH 3 Br budget imbalance.