People often think of contamination as particles, dust, dirt or some type of chemical residue. Lighthouse looks at contamination per the Institute of Environmental Sciences and Technology (IEST) definition: “Any foreign material or energy that has a detrimental effect on product or process.” Examples could be: Air or liquid borne particles Gas phase or airborne molecular contamination Electrostatic charge or electrostatic discharge Electromagnetic interference Fluctuations of cleanroom or minienvironment differential pressure Fluctuations of cleanroom temperature & relative humidity Vibration Surface particles Air changes