Monitoring the pollutant concentration is fundamentally important to develop and evaluate pollution control strategies. It is important to ensure that the measured air quality provides adequate and accurate information. One of the key factors affecting the accuracy of monitoring data is the location and placement of the air quality monitor. This paper describes how to carry-out representative air quality monitoring which serves the objective of the monitoring in the most accurate and scientific manner. It also describes the site specific and local factors that affect data quality, like topography, meteorological conditions etc.