We report on the production and transport of the 0.4 Tg of nitric oxide generated in the Siberian upper troposphere by the 1908 Tunguska object. The simulation uses a three-dimensional chemistry and transport model of the global troposphere. We find that much of the nitric oxide forms nitric acid that deposits downwind of the blast site within the first month, with no severe damage to the ecosystem caused by acid rain. Ozone and OH are totally scavenged locally soon after the impact, then they increase respectively by up to 30% and 200% during the first weeks. The total deposition below the explosion is simulated within a factor of 2 of that indicated by an analysis of peat samples. Considering the details of the model this may be the first reasonable calculation on the acid deposition distribution, and could help in locating interesting sites for future peat samples collection.