How do we Monitor?

Air pollution in Islington is monitored by the Pollution Team. There are two main types of air pollution monitoring equipment which are routinely employed; Passive Sampling (non-automatic) and Continuous Analysers (automatic). Islington uses a combination of the two techniques.

Passive Sampling (non-automatic)

Islington has nineteen passive sampler sites monitoring nitrogen dioxide using diffusion tubes. Four of these are part of the UK Nitrogen Dioxide Network, and the sampling is carried out on behalf of DEFRA. Diffusion tubes provide an inexpensive method of screening air quality in the area. They provide general indications of concentrations and trends of pollutants over a period of time.

The tubes are usually mounted to lamp posts or buildings to give readings over a period of a month. The main benefit of using this method is the relative low cost which allows us to carrying out testing at a wider number of locations.

For more information regarding the UK Nitrogen Dioxide Network, visit the AEAT website (see the link on the right).

Continuous Analysers (automatic)

Islington has two continuous analysers, commonly referred to as automatic monitoring stations. They are a more expensive method of air quality monitoring compared to the passive sampling, however the information collated is usually more accurate and reliable. Air is continuously pumped into each analyser and the level of pollutant in the air is recorded. The pollution levels are stored by a logger and maybe accessed remotely by a modem.

The monitoring stations are part of the London Air Quality Network, for more information see the King's College Environmental Research Group website (see link on the right).

For further information regarding the monitoring of pollutants see the 3rd stage review and assessment report.

Where are these Pollutants Monitored in Islington?

The Pollution Team monitor pollution levels at many sites across the borough. Unfortunately, we are not able to monitor every street, so sites have been chosen to represent different locations across the borough. Twenty one sites have been chosen to provide a general picture of air pollution. Sites fall into two categories; roadside or background depending on the distance from a busy road.

There are 19 diffusion tubes, which provide data on the average monthly levels of nitrogen dioxide. Nine of the tubes are in roadside locations and ten of the tubes provide background levels.

Islington has two continuous monitoring sites located at 159 Upper Street (background) and on the Holloway Road (roadside). Both stations monitor Nitrogen Dioxide and Particulate (PM10) and the Holloway Road site also monitors Carbon Monoxide.

To view a map of the monitoring sites in the borough, click the link below.