Tougher pollution laws on sulphur in fuel oil that will come into effect from July could lead to lower exports as it pushes refineries to change their crude slates, traders and refiners said yesterday. From July 1, sulphur in fuel oil will be cut to 0.3 percent from 0.5 percent in 14 cities, including Seoul, Pusan and Taegu, as part of the government's plan to reduce sulphur dioxide emissions, the Ministry of Commerce, Industry and Energy said.