Corrosion of electronics due to ambient air pollution has been documented for many years. Historically, the problem occurred only at industrial sites such as pulp and paper mills, and petrochemical refineries. These industrial facilities produce local environments relatively high in hydrogen sulfide. New environmental regulations have caused many electronic equipment manufacturers to change materials in their products that are more susceptible to gaseous corrosion. These new circuit boards can fail quickly even in Moderate environments, previously thought to cause problems only after long periods of time. In 2011, ASHRAE published Gaseous and Particulate Contamination Guidelines for Data Centers which describes the harmful effects of once benign contaminants.