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Monitoring Air Quality

Pollutants that have been or are currently being 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 to Nitrogen Dioxide, which is considered harmful to health and is therefore regulated.

The main sources of Nitrogen Oxide are vehicles and industrial combustion process. Ongoing monitoring in Wrexham County Borough 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.

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

Sulphur Dioxide (SO2)

The main source of Sulphur Dioxide (SO2) is when a sulphur containing fuel (typically coal or heavy oils) is burnt. The UK’s principle source is power stations that still burn these fossil fuels. Though domestic coal burning can also give rise to high levels of SO2 at the local level. Ongoing monitoring in Wrexham County Borough 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.

The main health concern for exposure to SO2 will predominately be felt by asthmatic’s. 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. Sulphur dioxide pollution is considered more harmful in combination with other pollution when exposed to high levels.

Smoke

The main source’s of smoke are from industrial and domestic combustion process. A majority of Wrexham town is a smoke control area, which has been done to reduce pollution from domestic chimneys within the County Borough by prohibiting the burning of fuels such as (certain types of) coal and wood on open fires. Industrial and trade premises are required to operate under the Clean Air Act (external link) which prohibits the emission of dark smoke unless a furnace is being lit from cold, there is mechanical failure or suitable fuel is not available.

Smoke is not specifically mentioned within the Air Quality (Wales) Regulations 2000. Though many of the other pollutants caused by combustion of solid fuel (e.g. SO2, PM10, etc) are.

The health concerns for smoke will be most significantly felt by those with asthma and other respiratory concerns and will mainly include difficulty in breathing. As well as the health concerns listed for SO2 and PM10 depending on the type of fuel being burnt.

Carbon Monoxide (CO)

The main source of Carbon Monoxide is again road transport, and in particular petrol engine vehicles. It is produced by incomplete or inefficient combustion of fuel. Monitoring in Wrexham County Borough has shown that the levels of CO are below the targets as outlined in the Air Quality (Wales) Regulations.

The health effects of exposure are that Carbon Monoxide prevents the normal transport of oxygen in the blood stream, which can effect people suffering from heart disease.

Ozone (O3)

Ozone is not directly emitted from any human process in significant quantities. It is formed by the chemical reaction caused by sunlight of volatile organic compounds (VOC’s) with Nitrogen Oxides (NOx). These reactions are not instantaneous and can take up to several days to complete, which can mean that the original NOx and/or VOC's emissions which have caused the Ozone occurred many miles away.

VOC’s are emitted from vehicles and industrial combustion process’s as for NO, but may also arise from both solvent and petrol usage. Monitoring in Wrexham County Borough has shown that the levels of O3 are below the targets as outlined in the Air Quality (Wales) Regulations.

Ozone irritates the lungs airways, which can cause a worsening of symptoms experienced by asthma and lung disease suffers.

Fine Particulates (PM10/ PM2.5)

Fine particulates is a catch all term for a wide variety of materials which 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 (e.g. 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 ┬Ám (i.e. 10 millionths of a meter). PM10 has been the focused to date of Air Quality strategies because of its effect on health, though PM2.5 is also becoming of increasing interest. Ongoing monitoring in Wrexham County Borough has shown that the levels of PM10 are below the targets as outlined in the Air Quality (Wales) Regulations.

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. In addition, they may carry surface-absorbed carcinogenic compounds into the lungs.

Benzene (CcHc)

Benzene is a Volatile Organic Compound (VOC) which is a minor constituent of petrol. The main sources of benzene in the atmosphere in Europe are the distribution and combustion of petrol. Of these, petrol vehicles are the single biggest source (70% of total emissions). Ongoing monitoring in Wrexham County Borough has shown that the levels of Benzene are below the targets as outlined in the Air Quality (Wales) Regulations, and are likely to remain so.

Possible chronic health effects associated with Benzene include cancer, central nervous system disorders, liver and kidney damage, reproductive disorders, and birth defects.

In addition to the above regulated air pollutants the Environment and Planning Department also monitors for other air borne pollutants and one example of this is Formaldehyde.

Formaldehyde (HCHO)

Formaldehyde is a colourless gas with a pungent odour. It occurs both naturally, as an intermediary in the methane cycle and also occurs in the early stages of plant decomposition in the soil. Artificial sources are from cars not fitted with catalytic converters. Other man made sources are emissions from formaldehyde production and consuming process e.g., adhesives in the production of particleboard, fibreboard and plywood. Additionally cigarettes smoking will lead to direct formaldehyde exposure. Formaldehyde in the atmosphere is readily broken down into carbon dioxide in sunlight.

Formaldehyde irritates the eyes and throat. At higher levels it can cause a worsening of symptoms experienced by those with respiratory concerns.

The remaining pollutants from the national and Welsh air quality standards are not currently considered to be present within the County Borough in high enough concentrations to warrant monitoring. However, the Environment and Planning Department maintains awareness of current processes within the County Borough and proposed new processes. Hence should the need arise, monitoring can be expanded to include these other pollutants.

The remaining pollutants from the national and Welsh air quality standards are not currently considered to be present within the County Borough in high enough concentrations to warrant monitoring. However, the Environment and Planning Department maintains awareness of current processes within the County Borough and proposed new processes. Hence should the need arise; monitoring can be expanded to include these other pollutants.