Prolonged, multiple unprotected exposures to the chemicals involved in manufacturing illegal drugs are a health risk. Operators of clandestine labs are typically not trained chemists and do not follow conventional chemical manufacturing practices. The law enforcement officer entering such a lab may be exposed to chemical concentrations well above recommended or mandated safety levels. These levels may not immediately cause observable health effects, but exposure to them over time can cause serious, debilitating, and even life-threatening illnesses. The article lists some of the chemicals commonly found in clandestine drug labs, the type of hazard they represent, the route by which the chemicals can enter the body, maximum exposure concentrations, the type of personal protective equipment required, the symptoms that can be expected, and the body organs affected by exposure to the chemicals. In nearly every case respiratory protection is a necessity. Officers are advised to use full facepiece respirators or Self Contained Breathing Apparatus to provide protection to the lungs. Additionally, every chemical listed also is a contact hazard indicating the risk of chemical burns or frostbite freezing if the material comes in contact with the skin.