The paper addresses the optimization of emission control areas (ECAs) for shipping to minimize sulfur emissions. It proposes a mathematical programming model from the regulator's perspective to optimize the ECA width and sulfur limit, aiming to reduce total sulfur emissions. An internal model from the shipping liner's perspective is developed to determine detoured voyages, sailing speeds, and cargo transport volumes to maximize liner profit. A hybrid algorithm based on variable neighborhood search (VNS) meta-heuristic is designed to solve these models efficiently. The methodology is validated through numerical experiments and sensitivity analyses, showing that the optimal ECA design can significantly reduce sulfur emissions. The study also extends the methodology to incorporate heterogeneous sulfur limits, providing a more flexible approach for future ECA designs.The paper addresses the optimization of emission control areas (ECAs) for shipping to minimize sulfur emissions. It proposes a mathematical programming model from the regulator's perspective to optimize the ECA width and sulfur limit, aiming to reduce total sulfur emissions. An internal model from the shipping liner's perspective is developed to determine detoured voyages, sailing speeds, and cargo transport volumes to maximize liner profit. A hybrid algorithm based on variable neighborhood search (VNS) meta-heuristic is designed to solve these models efficiently. The methodology is validated through numerical experiments and sensitivity analyses, showing that the optimal ECA design can significantly reduce sulfur emissions. The study also extends the methodology to incorporate heterogeneous sulfur limits, providing a more flexible approach for future ECA designs.