Aircraft are an important source of both soot aerosols and pollutants, like CO₂ and nitrogen oxides (NO_x), which also negatively affect human health and the environment. In many cases, strategies to reduce one pollutant may increase another. So, it is vital to have a quantitative understanding of the contribution of each pollutant to negative outcomes so that trade-offs can be made. Here, we review methods to reduce aircraft soot emissions through the use of fuel, engine design, and operation.