Notes that airborne contaminants can cause various types of failures in electronic equipment. Examines the effects of ventilation on three different classes of contaminants - fine particles, volatile organic compounds and inorganic gases. States the results are derived from more than nine years of detailed studies at telephone switching offices across the USA. States that measurements and modelling demonstrate that contaminant concentrations decrease or increase in a non-linear fashion with the ventilation rate. Ventilation is essential to control the concentration of contaminants with indoor sources but can also increase indoor levels of contaminants with outdoor sources such as fine particles. Explains how with the use of proper filters adequate ventilation can be maintained without a significant increase in indoor concentration of contaminants with outdoor sources.

KEYWORDS: Electronic, contaminants, contaminants, particles, gases, organic compounds, equipment, USA, switchboards, telephone equipment, telephone exchanges, indoor, air quality, ventilation, air filters, air cleaning, electrical installations