Natural gas fired crematories and incinerators that combust human remains, animal remains, refuse, agricultural products, or medical waste are sources of carbon monoxide, nitrogen oxides, particulate matter, organic compounds, sulfur oxides and trace toxic substances. Incinerators used for cremation purposes are called "retorts" and the remains are referred to as "charges." Emissions of trace toxics substances may include hydrogen chloride, formaldehyde, benzene, toluene, mercury, hexavalent chromium, PAH's, and other heavy metals. Incinerators in San Diego County typically have a primary burner in the main chamber and a secondary burner/afterburner in the flue stack. Most permits include lb/hour charge rate limitations and periodic particulate matter source testing requirements. Emissions from these processes are highly dependent upon equipment type, control devices, operating conditions, fuel type, process time, and waste stream composition.