The following air pollutants are measured in the County Borough.

Nitrogen dioxide (NO2) and oxides of nitrogen (NOx)

NOx is the catchall term for oxides of nitrogen and consists of both nitrogen oxide (NO) and nitrogen dioxide (NO2). 

Nitrogen oxide is not considered harmful to health but once it has been emitted into the atmosphere it is rapidly oxidised, forming NO2. NO2 is considered harmful to health and is therefore regulated.

The main sources of NO are vehicles and industrial combustion process. 

The main health concerns of exposure to higher levels of NO2 are irritation to the lungs and a lowered resistance to respiratory infections. Prolonged exposure can cause an increase in acute respiratory illness in children.

Ongoing monitoring in Wrexham County has shown that the levels of NO2 are below the targets as outlined in the Air Quality (Wales) Regulations, and are likely to remain so.

Sulphur dioxide (SO2)

Sulphur dioxide (SO2) is produced when a sulphur containing fuel (typically coal or heavy oils) is burnt. 

The UK’s main source is power stations that still burn these fossil fuels. Domestic coal burning can also lead to high levels of SO2 at the local level. 

The main health concern for exposure to SO2 is for those who are asthmatic. Tightness in the chest and coughing occur at high levels, and lung function of asthmatics may be impaired to the extent that medical help is required. 

SO2 pollution is considered more harmful when combined with high levels of other types of air pollution.

Ongoing monitoring in Wrexham County has shown that the levels of SO2 are below the targets as outlined in the Air Quality (Wales) Regulations, and are likely to remain so.

Fine particulates (PM10/ PM2.5)

Fine particulates is a catch all term for a wide variety of materials that arise from a variety of sources:

  1. Combustion sources (mainly road traffic)
  2. Secondary particles, mainly sulphate and nitrate formed by chemical reactions in the atmosphere, and often transported from far across Europe
  3. Coarse particles, suspended soils and dusts (for example from the Sahara), sea-salt, biological particles and particles from construction work

Fine particulates are described in a number of different sizes, with PM10 referring to particles with an aerodynamic diameter of 10 µm (meaning 10 millionths of a meter).

Air quality strategies have focused on PM10 because of its effect on health, though PM2.5 is also becoming of increasing interest. 

Fine particles can be carried deep into the lungs where they can cause inflammation and a worsening of the condition of people with heart and lung diseases. They may also carry surface-absorbed carcinogenic compounds into the lungs.

Ongoing monitoring in Wrexham County has shown that the levels of PM10 are below the targets outlined in the Air Quality (Wales) Regulations.

How we measure air pollution

We monitor air pollution in Wrexham County in two ways: automatic and non-automatic.

Automatic monitoring

There are three automatic monitoring stations in Wrexham County:

  1. Victoria Road – this station is part of the Automatic Urban and Rural Network (AURN) which is a network of air quality stations that covers the UK. The station continuously monitors for oxides of nitrogen (NOx), sulphur dioxide (SO2) and particulate matter (PM10 and PM2.5)
  2. Lloyds Lane, Chirk – we own and maintain this station. It continuously monitors for oxides of nitrogen (NOx), volatile organic compounds (VOCs) and particulate matter (PM10 and PM2.5) 
  3. Chirk Community Hospital, Chirk – we also own and maintain this station. It monitors for the same pollutants as the Lloyds Lane site.

You can find details along with current and past measurements of air quality levels for all of these sites on the Air Quality in Wales website. 

Air Quality in Wales: Wrexham Victoria Road site (external link)
Air Quality in Wales: Wrexham Chirk site (external link)
Air Quality in Wales: Wrexham Chirk Community Hospital site (external link)

Non-automatic monitoring

We carry out non-automatic monitoring of NO2 using diffusion tubes. These are a simple and cost effective way to measure pollutants over a period of time (usually one month).

The diffusion tubes are exposed all over the county borough each month, then sent to an independent laboratory for analysis. You can find some of the results on the Air Quality in Wales website (external link).

Where we measure air pollution 

We measure air pollution at several locations throughout Wrexham County Borough, as shown on the map linked below.

Air pollution measurement locations in Wrexham County (external link)