The rise will affect not only millions of Polish drivers, but also the prices of all products. Diesel users will be hit the worst. "Diesel oil isn't any different from oil used to heat buildings. And when this gets more expensive, diesel oil prices automatically jump up," said petrochemical expert Andrzej Szczęśniak. The cause of the rising prices is oil, which is in shorter supply over the winter, and therefore more expensive. LPG prices will be affected by regulations raising the proportion of propane in the mixture from 40 percent to 50 percent.