The present invention relates to systems and methods for controlled combustion and decomposition of gaseous pollutants while reducing deposition of unwanted reaction products from within the treatment systems. The systems include a novel thermal reaction chamber design having stacked reticulated ceramic rings through which fluid, e.g., gases, may be directed to form a boundary layer along the interior wall of the thermal reaction chamber, thereby reducing particulate matter buildup thereon. The systems further include the introduction of fluids from the center pilot jet to alter the aerodynamics of the interior of the thermal reaction chamber.