The study found a strong link between the amount of sulfur trioxide in coal ash and the levels of calcium oxide and total sulfur in the coal. By analyzing 227 coal samples from different regions in Siberia, researchers developed equations to accurately predict sulfur trioxide content in coal ash. They also suggested improvements to existing methods for calculating calcium sulfate levels in the ash. This research can help improve the accuracy of measuring sulfur trioxide content in coal ash, especially in coals with low sulfur levels.