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Monitoring Air Pollution

Air monitoring methodologies can be divided into five main types, covering a wide range of costs and performance levels. The methods and their relative merits are shown in the table below and discussed in the following section. The use of a particular type of monitoring equipment may need to be justified in review and assessment reports and therefore should be chosen appropriately.

It is also important to choose the most appropriate monitoring location for investigating a specific air pollution source or problem.

Method Advantages Disadvantages
Passive Sampling Low cost/simple. Useful for screening and base-line studies and in support of automatic monitoring for Detailed Assessments.  Unproven for some pollutants. Laboratory analysis required. In general, only provide weekly or longer averages. 
Photochemical and Optical Sensor Systems Can be used portably.  Low sensitivity may only provide spot measurements. 
Active (Semi-Automatic) Sampling Low cost/easy to operate - reliable. Historical datasets available from UK networks.  Provide daily averages. Some methods are labour intensive. Laboratory analysis required. 
Automatic Point Monitoring Provide high resolution data. On-line data collection possible. Provide path or range-resolved data.  Relatively expensive. Trained operator required. Regular service and maintenance costs. 
Remote Optical/Long-Path Monitoring Useful near sources. Multi-component measurements possible.  Relatively expensive. Trained operator required. Data not readily comparable with point measurements. 

Since monitoring instrumentation covers a wide range in capital and running costs, it is usually advisable to choose the simplest method available to meet the specified monitoring objectives. Many baseline monitoring, spatial screening and indicative surveys can be served perfectly well by inexpensive active or passive sampling methods. Only proven and generally accepted measurement methods should be considered.