The objective of this paper is to determine how policy instruments which aim to achieve a modal shift of long-haul freight transport from road to rail or sea affect the direct emissions to air of greenhouse gases, nitrogen oxides, sulfur dioxides, volatile organic compounds, and particulate matter. The analysis is conducted in two stages. First, a range of forecasts reflecting different assumptions are applied using the Swedish national freight transport model (SAMGODS) to derive a range of possible future developments of emissions levels up to 2030 and 2040. This has involved determining emission factors per tonne-km for each of the SAMGODS model's six road freight vehicle types, eleven freight train variants and 22 ship types. The model outcomes are then compared to those of the base year of 2017. Second, the effects of two hypothetical modal shift policy instruments are analyzed with respect to their potential impact on emissions to air. The effects of these two policy instruments are evaluated for the base-year of 2017 and for the 2030 and 2040 forecasts. The paper also analyzes whether the Swedish climate objective for domestic transport in 2030 can be expected to be fulfilled given different forecasts and policy instruments. Within the context of a predicted large increase in total freight tonne-km (between 31 and 53%), emissions of greenhouse gases are calculated to decrease by 50 to 60% by 2040. This means that the Swedish freight transport sector will not achieve its share of greenhouse gas emissions reductions necessary to attain the national climate objective of a 70% reduction by 2030. Emissions of nitrogen oxides (NOx) are forecast to reduce by between 60 and 75%, emissions of sulfur dioxides to reduce by between 41 and 50%, emissions of volatile organic compounds to increase by 8 to 30% and emissions of particulate matter (from exhaust and tyre/road wear) are calculated to increase by between 13 and 33%. Using modal shift policy instruments to achieve greenhouse gas reductions is calculated to attain worse results over time, by 2040 it might even be counterproductive.