Electric vehicles (EVs) and plug-in hybrid EVs (PHEVs) are increasingly being seen as a means of mitigating the pressing concerns of traffic-related pollution. While hybrid vehicles are usually designed with the objective of minimizing fuel consumption, in this paper we propose a engine management strategies that also consider environmental effects of the vehicles to pedestrians outside of the vehicles. Specifically, we present the optimisation-based engine energy management strategies for PHEVs that attempt to minimize the environmental impact of pedestrians along the route of the vehicle, while taking account of route-dependent uncertainties. We implement the proposed approach in a real PHEV and evaluate the performance in a hardware-in-the-loop platform. A variety of simulation results are given to illustrate the efficacy of our proposed approach.