How Is Air Pollution Being Measured?

Wrexham County Borough Councils Public Protection Department monitors air pollution in 2 ways, automatic and non-automatic.

Automatic Monitoring

There is one automatic monitoring station within the County Borough, which is situated near to Wrexham Town (Victoria road). The station continuously monitors Oxides of Nitrogen (NOx), Sulphur Dioxide (SO²) and Carbon Monoxide (CO). The current levels can be viewed on the website of the Welsh Air Quality Forum (external link). The UK National Air Quality Information Archive (external link) also provides historical data.

The station is part of the Automatic Urban and Rural Network (AURN) which is organised by the Welsh Assembly Government. The AURN currently consists of twenty stations in Wales (external link), and is part of the much wider network, which also includes stations in England, Scotland and Northern Ireland.

The automatic monitoring station also has the facility to measure the amount of particulate matter present in the air. This monitoring is not real time, though historical data (external link) is accessible by selecting the dates of interest.

The Automatic Urban and Rural Network Station at Victoria Road

Inside of the Automatic Urban and Rural Network Station

Non Automatic Monitoring

There are several methods of non-automatic monitoring (also known as passive) and Wrexham County Borough Council uses three different types of technology:

• Diffusion Tubes
• Partisol plus PM10 monitor
• Dust Frisbee

Diffusion Tubes

Diffusion tubes are a simple and cost effective way to measure pollutants over a period of time (usually one month) and the Housing and Public Protection Department uses these tubes to monitor four types of pollution:

• Nitrogen Dioxide (type of tube shown on the left in the picture below)
• Sulphur Dioxide
• Ozone
• Benzene (type of tube shown on the right in the picture below)

Over twenty diffusion tubes are exposed all over the County Borough each month. At the end of each month the exposed tubes are sent off to an independent laboratory for analysis and the most recent results as well as older data can be viewed.

Particulate Plus PM¹⁰ Monitor

Particulate matter (PM¹⁰) is measured at one fixed location and two transient locations in the County Borough using Partisol Plus monitors. These Partisol's draw air onto a pre-weighed filter over a twenty-four hour period. The exposed filter is then re-weighed and a simple calculation will determine the amount of Particulate Matter in the surrounding area.

The two transient monitors are often compared to the fixed location at Victoria road, which is used to determine the background level for the entire County Borough as it is in an ideal location, on the boarder of a Smoke Control Area and away from any major sources of industry.

Partisol Plus PM¹⁰ Monitor

Dust Frisbee

The Housing and Public Protection Department currently utilises two dust frisbee's to monitor for dust within the County Borough. This technique monitors for larger dust sizes than the Partisol Plus PM¹⁰ monitors described above, and focuses more on the nuisance levels than the health implications specified in the Air Quality Standards.

The frisbee's work by collecting dust falling out of the atmosphere onto the frisbee section, which is then washed down into a collection bottle by rain. The bottle is then sent off to an independent laboratory where the dust is filtered from the rainwater and weighed. A simple calculation then allows for the determination of the amount of dust in the monitoring area on a daily basis.

Dust Frisbee