Heat radiation, combustion products, and flame engulfment are the main hazards from a fire event. Several reports have indicated that fire toxicity has caused greater numbers of human injuries and fatalities than those of heat radiation and flame engulfment. In a complex facility, the risk of fire toxicity increases significantly due to the difficulty of escaping in cases of emergency rescue and evacuation operations. This study proposes a methodology to model the impact of combustion products on humans. Several fire scenarios were considered to identify credible fire scenarios. In the most credible fire scenario, concentrations of combustion products over the layout of a facility were modeled. The results showed that the concentrations of CO and CO2 are below the short-term exposure limit and lethal concentration 50 threshold limits at the considered time. The possible reasons for this are that the fire location was in a well-ventilated area and equipment layouts were designed with proper safety gaps replicating a full-scale dimension of an operating floating liquefied natural gas processing facility. The concentration of soot is above the threshold limit, and this has the potential to cause adverse health effects. This study can provide a tool for assessing fire toxicity in processing facilities, which will help improve safety measures.