Background to Air Pollution Measurement and Monitoring
This page outlines the council’s operations for monitoring air pollution.
Why do we monitor air pollution?
Air pollution has been monitored in the UK for many years. The council has participated in national networks providing information on air quality in the borough for 25 years. New duties under the Environment Act 1995
The information we collect is used to help us review and assess air quality in the borough, to measure whether air quality standards are being met, to provide good local information for policy decisions and provide the community with information on the air it breathes.
What pollutants are monitored?
Environmental Health Services continuously measures levels of air pollutants nitrogen dioxide (N02) and particulate matter (PM10) at Water Street in central Lancaster. Monthly measurements are made of nitrogen dioxide, fine particulate matter, sulphur dioxide and ozone using inexpensive equipment at around 45 locations across the Lancaster district.
How do we monitor?
Air pollution in Lancaster City Council’s District is monitored by the Environmental Protection Team. There are two main types of air pollution monitoring equipment which are routinely employed; Passive Sampling (non-automatic) and Continuous Analysers (automatic). The City Council uses a combination of the two techniques together with an old-style but useful non-continuous method.
Passive Sampling (non-automatic)
Lancaster City Council has about 45 passive sampler sites monitoring nitrogen dioxide using diffusion tubes. Four of these are part of the UK Nitrogen Dioxide Network, and the sampling results are passed to 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 building frontages to give readings over a period of a month. The main benefit of using this method is the relatively low cost, allowing us to carrying out monitoring at a wider range of locations.
For more information regarding the UK Nitrogen Dioxide Network, visit www.aeat-env.com.
Continuous Analysers (automatic)
The City Council has one automatic monitoring station continuously measuring air pollution levels at water Street in Lancaster city centre. The station provides a more expensive method of air quality monitoring compared to the passive sampling, however the information collated is usually accurate and highly reliable. The monitoring station contains three analysers, one each measuring nitrogen dioxide (No2) and fine particulate matter (PM10). Air is continuously pumped into each analyser and the level of pollutant in the air is recorded. The pollution levels are stored by a data logger and accessed remotely by a computer and modem.
Further information regarding the monitoring of pollutants is provided in our air quality review and assessment reports.
Where do we monitor?
Environmental Health Services monitors pollution levels at many sites across the district. Unfortunately, we are not able to monitor every street, so sites have been chosen to represent different locations across the borough. Some sites have been selected where air pollution levels might be highest or present particular threats. Sites fall into two categories – roadside or background depending on the distance from a busy road.
There are about 45 diffusion tubes in all, providing data monthly averaged measurements of nitrogen dioxide.
The continuous monitoring station is located on Water Street in Lancaster, close to the A6 Cable Street.