This paper proposes a new approach to calculate local air pollution exposure costs in large-scale urban settings by taking the number of exposed agents into consideration. It avoids the need for detailed air pollution concentration calculations and is characterized by little data requirements, reasonable computation times for iterative calculations, and open-source compatibility. The approach is applied to a simple test scenario and then to a large-scale real-world scenario of the Munich metropolitan area in Germany. The paper shows (i) how to derive time-dependent vehicle-specific exposure tolls which approximate marginal social costs, (ii) how to estimate changes in system welfare for such pricing scheme when including exhaust emission cost reductions, and (iii) how this approach can be used as benchmark for other transport policy interventions.