The Caralight photochemical system economically controls the dioxin-furan emissions from wet, long dry, preheater, and preheater-precalciner cement kilns. For kilns having in-line raw mills, the Caralight photochemical system can reduce energy costs by using different energy levels during mill-on and mill-off conditions. The Caralight photochemical system allows kiln operators to avoid corrosion damage to electrostatic precipitators and fabric filters by slightly increasing the maximum inlet gas temperatures without increasing dioxin-furan emissions.