Air Pollution Guide » Air pollution in Port Talbot

Pollution GuideFind out about the following:
Key Points:
  • Benchmarks have been set for each of the major pollutants, against which pollution levels can be compared.
  • 'Air Quality Standards' have been agreed by a panel of health experts for each of the major pollutants. Levels of pollution below these standards are considered acceptable in the light of what is known about each pollutant's effects on health and the environment.
  • 'Air Pollution Bands' classify pollution levels into bands. These are intended as a tool to help the public assess the possible health impacts of pollution above certain thresholds.
  • 'The Air Pollution Index' was introduced to give more specific information on pollution levels using an easily understandable index system. The index fits within the Air Pollution Bands.
  • 'Air Quality Objectives' represent the Government's targets for improving air quality in the medium term (approximately the next five years).
  • Local authorities must assess pollution levels in their district and draw up action plans if these objectives are unlikely to be met.
  • Particulate pollution episodes occur when easterly winds bring high levels of particulate matter from industrial areas of central Europe.
  • Plume grounding episodes occur when specific weather conditions push emissions from large industrial chimney stacks down to ground level.
Back to top
Air Quality Standards
Air Quality Standards have been decided for each of the eight major pollutants. Each one is set at a concentration, measured over a given time period, below which pollution levels are considered acceptable in the light of what is known about its effects on health and the environment.
An 'exceedence' of a standard is a period of time where the concentration is higher than that set down. Any day when such an exceedence occurs, is described as an 'exceedence day'. An example is given below:
The Standard for nitrogen dioxide is 150ppb measured as a one hour mean. An analyser records hourly mean concentrations above 150ppb between 10:00pm on the 1st December and 04:00am on the 2 nd December. Therefore, the Air Quality Standard for nitrogen dioxide was exceeded six times on two exceedence days.
Back to top
Air Quality Bands
As mentioned above, air pollution levels have been classified into bands. These bands help the public to assess the possible health impacts of pollution above certain thresholds (shown in part 2).
The first of these thresholds, the 'Standard Threshold', is based on the Air Quality Standard for each pollutant. Further thresholds are the 'Information' and 'Alert' levels that are in line with EC Directives on Air Quality. The bands and thresholds which separate them, are shown below.
Any concentration below the Standard threshold is described as 'Low air pollution'. A level between the Standard and Information thresholds would be described as 'Moderate', between the Information and Alert thresholds is 'High', and above the Alert threshold is 'Very High'.
Each band is split into index categories. It was felt that the bands alone did not give sufficient detail on pollution levels, and the index system now forms the basis of air quality reporting throughout the UK.
The time taken for exposure to a pollutant to cause adverse health effects varies from pollutant to pollutant. The times over which concentrations are averaged varies to reflect this.
The table below shows the relationship between the Air Pollution Bands and their thresholds:
Back to top
Description Low Moderate High Very High
Sulphur Dioxide (ppb, 15 minute averages) <100 S 100-199 I 200-399 A >=400
Ozone (ppb) <50 (8hr running average) 50-89 (hourly average) 90-179 (hourly average) >=180 (hourly average)
Carbon Monoxide (ppm, 8 hour running average) <10 10-14 15-19 >=20
Nitrogen Dioxide (ppb, hourly average) <150 150-299 300-399 >=400
PM10 Particles (g/m3, 24 hour running average) <50 50-74 75-99 >=100
S = Standard Threshold, I = Information Threshold, A = Alert Threshold
Back to top
Air Quality Objectives
Air quality regulations in this country are grouped together in the Government's Air Quality Strategy. This Strategy describes the Government's plans to improve and protect ambient air quality in the UK in the medium term. Its proposals aim to protect people's health and environment without imposing unacceptable economic or social costs.
Air Quality Objectives have been established by the Strategy for eight main pollutants. Emphasis has been placed on local authorities to assess pollution levels in their districts, and then work towards achieving these objectives by the specified dates.
The Government expects these objectives to be met by a combination of national measures, regulation of industrial processes and action at local level. Projections based on current data and modelling studies suggest that some of the objectives can be achieved through measures that are already in place, such as tighter control of vehicle emissions and regulation of industry. Other objectives will be more challenging and will require local authorities to take local action to reduce pollution in specific areas.
The objective for ozone is provisional, and not included in regulations. This is because pollutants produced outside of the UK heavily influence ozone levels. Reduction in ozone pollution will require combined international action.
The Air Quality Objectives and their target dates are shown below. These objectives are similar to the Air Quality Standards. The differences arise partly because the UK must comply with European Directives on air quality. Requirements placed on the UK by European Law must be integrated into UK Law. In some cases, UK-based standards have been replaced by European standards. In setting these Objectives the Government has considered cost and practicability.
Where it would be 'impractical' or excessively costly to reduce levels to below the Standard at all times, a number of 'allowed' exceedences are given. For example, the 100ppb sulphur dioxide Standard may be exceeded up to 35 times per year. The Air Quality Objectives were reviewed in 1999 and will continue to be reviewed at regular intervals in the future.
Back to top
National Air Quality Strategy - Air Quality Objectives
Benzene- 5ppb measured as running annual mean (31/12/2003)
1,3-Butadiene- 1ppb measured as running annual mean (31/12/2003)
*Nitrogen Dioxide (i)- 105ppb not to be exceeded more than 18 times a year measured as 1 hour mean (31/12/2005)
*Nitrogen Dioxide (ii)- 21ppb measured as annual mean (31/12/2005)
PM10 Particles (i)- 50 g/m3 not to be exceeded more than 35 times a year measured as 24 hour mean (31/12/2004)
PM10 Particles (ii)- 40 g/m3 measured as annual mean (31/12/2004)
Sulphur Dioxide (i)- 132ppb not to be exceeded more than 24 times a year measured as 1 hour mean (31/12/2004)
Sulphur Dioxide (ii)- 47ppb not to be exceeded more than 3 times A year measured as 24 hour mean (31/12/2004)
Sulphur Dioxide (iii)- 100ppb not to be exceeded more than 35 times a year measured as 15 minute mean (31/12/2005)
Carbon Monoxide- 10ppm measured as running 8 hour mean (31/12/2003)
**Ozone- 50ppb not to be exceeded more than 10 times a year measured as the daily max of running 8 hour mean (31/12/2005)
* Objectives are provisional

** Objective is outside of Local Quality Management regulation
Back to top