The Low Sulphur Fee (LSF) is a surcharge on sea freight costs that has arisen because of stricter environmental standards for sulfur oxide emissions in the shipping industry. These environmental standards require container ships to use low-sulfur fuel to improve air quality. The additional costs of this fuel are passed on to customers by shipping companies through this surcharge. The calculation may vary, but it typically involves a fixed amount per TEU (Twenty-foot Equivalent Unit).