Background concs    Road sources    Domestic fuel    Part A and B processes    Uncontrolled + fugitive emissions    Other transport sources
First Stage Review & Assessment
  1. To carry out the First Stage review and assessment, the authority should collate the following information:
  2. For each existing or proposed emissions source, the authority needs to identify those which have the potential, either singly or together, to emit significant quantities of PM10. Clearly, the sources will need to be in existence and/or in operation in 2004. Authorities are also reminded that only those sources which have the potential to cause exposure of the public at relevant locations (as described in para 12 above) need be considered. A recommended step-by-step approach for collating and interpreting this information is described below.

    Background PM10 concentrations

  3. The estimated annual mean background PM10 (gravimetric) concentration for 2004 is the starting point for the assessment. These data have been mapped for the UK by NETCEN, and can be accessed via the Internet (/netcen/airqual/). Details of the mapping process can be found at the Internet site. The maps have been prepared based upon atypical 1996 meteorology, and as such represent a worst case scenario. The maps allow the user to zoom in on a particular area of interest, in order to get the forecast PM10 concentrations (gravimetric) for 2004. When obtaining this information, authorities should note and record any variations in estimated concentrations across their areas.

    Road traffic sources

  4. The potential significance of PM10 emissions from road traffic is dependent upon a number of factors including the background concentration (for 2004), and traffic conditions such as the traffic flow, speed and HGV mix. The impact of traffic emissions falls off rapidly with increasing distance from the kerbside, and it is also important to take account of where the nearest exposed population will be. A suggested approach for identifying significant traffic emissions is described in Box 5.
  5. To simplify the assessment of road traffic emissions, two nomograms have been derived using the methodology set out in the Design Manual for Roads and Bridges (DMRB)7. These are shown in Figure 2, for a single carriageway road, and in Figure 3 for a dual carriageway road or motorway. Based upon a knowledge of the traffic flow and vehicle speed, it is possible to determine whether there is risk of exceeding the proposed objectives. Roads with daily average traffic flows of less than 5,000 vehicles per day are unlikely to have a significant impact. The nomograms may need to be applied to several roads or sections.

    Box 5: Assessment of the Significance of Traffic Emissions for First Stage Review and Assessment

  6. It should be noted that these nomograms are not appropriate for use where:
    daily average traffic speeds are less than 12.5 mph (20 kph) on single carriageway roads, or less than 40 mph (65 kph) on dual carriageways or motorways;
    there are properties closer than 2 metres of the kerbside of single carriageway roads, 10 metres of the kerbside of dual carriageways, or 15 metres of the hard shoulder of a motorway; or
    HGV traffic represents more than 12% of the total traffic flow.
    In such circumstances, it will be necessary to undertake a Second and/or Third Stage review and assessment.
  7. To use the nomograms, identify the point whose co-ordinates are at the annual mean background PM10 concentration for 2004 (derived from the Internet site) and the daily mean traffic flow. If this point lies on or above the line, there is a risk of exceeding the proposed objectives. If the point is below the line, the road traffic may be considered to be insignificant, and it should not be necessary to proceed further. For example, on a single carriageway urban road with a predicted 2004 background PM10 concentration of 24 µg/m3, gravimetric, and an average daily traffic speed of 12.5 mph, it would only be necessary to proceed to a Second and/or Third Stage review and assessment if the traffic flow exceeded 20,000 vehicles per day.

    Domestic solid fuel use

  8. Solid fuel burning for domestic heating has largely been replaced by alternative fuels throughout most of the UK. However, there are a few areas where there is still significant solid fuel burning, which may have the potential to cause exceedances of the proposed objectives. The risk of exceedance within an area may be quickly assessed by calculating the number of people per square kilometre within coal burning households in the area. A step-by-step procedure for this exercise is given in Box 6. The calculated number of people in coal burning households may then be compared with the nomograms in Figure 4.
  9. Three representative 'area types' have been considered i.e.;
    a small village (approx 1 km    2 area)
    a small town (approx 16 km    2 area)
    a large town (approx 100 km    2 area)
  10. Users should select the area most appropriate to their situation. Where there is doubt, the larger area should be chosen eg a large village would be represented as a 'small town'.
  11. As a worked example, assume there is a small town where a significant proportion of the population burns coal. Other assumptions for this example are:
    a density [P] of 8000 people per km    2 in the most densely populated area;
    30% open space or parkland [L] in the most densely populated area; and
    20% of the households in the most populated area burn coal [C].
  12. From Box 6, the maximum number of people in households burning coal [D] is calculated to be 8000 x 0.2/(1-0.3) = 2285 per km2. If, for example, a background annual mean PM10 concentration in 2004 of 23 mg/m3 is assumed (derived from the Internet maps) then Figure 4 shows that for a small town, there is a likelihood of the objectives being exceeded if the density of coal burning exceeds 1000 people per km2. As the estimated density exceeds this figure, there is a potential to exceed the objectives in this given example, and the authority would proceed to the Second and/or Third Stage.
  13. For areas which have Smokeless Solid Fuel (SSF) burning, it is recommended that authorities assume that 10% of the households in the area burn coal (unless precise details are known), and then follow the methodology in Box 6 as described above.

    BOX 6: Assessment of the Significance of Domestic Solid Fuel Burning


    Part A and Part B authorised processes:

  14. A list of both Part A and Part B processes with the potential to emit significant quantities of PM10 is provided in Table 2. If any of these processes are present or are planned within the area, the authority should proceed to a Second and/or Third Stage review and assessment. Due to the wide variety of processes and release conditions that may apply, it is difficult to provide suitable screening mechanisms at this stage. However, it is advised that authorities should not need to consider sources which lie at a distance of 5 km or greater from the nearest sensitive receptor location, as these will be insignificant in terms of PM10 emissions.
  15. The list in Table 2 should not be regarded as definitive or exclusive. Local authorities may wish to use their professional judgment and local knowledge to determine if processes not included in Table 2 should additionally be considered.

    Uncontrolled and fugitive emissions

  16. There is the potential for dust emissions within the PM10 size fraction to arise from a variety of uncontrolled and fugitive sources. These include, but are not limited to:
    • quarrying and mineral extraction processes;
    • landfill sites;
    • coal and material stockyards, or materials loading/unloading;
    • major construction works.

  17. Emissions from these sources are not well quantified, and it is therefore difficult to predict PM10 concentrations with any accuracy. The First Stage review and assessment is therefore based upon practical experience gained from studies in the vicinity of these types of sources, which provide an indication as to whether a problem is likely to exist or not. In all cases, it should be noted that these sources will only impact upon the proposed objectives if they are in operation at the end of 2004. Short-term construction works do not normally need to be considered for the purpose of review and assessment.

    Quarrying, stockpiles, landfill sites
  18. Dust emissions from quarrying and materials handling tend to be within the larger particle size fractions, and correspondingly fall out from the atmosphere rapidly with increasing distance from the source. Monitoring studies completed by the First Phase authorities (see The First Phase Air Quality Review and Assessment: A Summary8) have indicated few, if any, exceedances of the proposed objectives in the vicinity of quarrying activities, although the potential for problems does depend upon the type of material handled. Due to the uncertainties involved, where local monitoring data are available, it is recommended that authorities proceed to a Second Stage review and assessment. In the absence of any monitoring data, the following approach is suggested:
    • If there are no properties within 400 metres of the dust emissions sources there is no need to proceed further (NOTE: the distance should be taken from the source, and not from the site boundary).
    • If there are properties within 200-400 metres of the dust emissions sources, some further selection criteria are provided in Table 3.
    • Where properties lie closer than 200 metres to the source, authorities are advised to investigate whether any dust nuisance complaints have been reported. In the absence of any complaints, it may be assumed that the source is insignificant, and there is no need to proceed further.
  19. It must be emphasised that these criteria are subject to greater uncertainty than those prepared for other source types. In case of any doubt, authorities are advised to proceed to Second or Third Stage reviews and assessments as necessary.
  20. If none of the sources or activities described above exist or are planned in the area, or they fall below the significance criteria provided above, then it may be judged that there is negligible risk of the proposed objectives being exceeded, and the authority is recommended to proceed no further. Where significant sources have been identified, or the degree of significance cannot be judged without more detailed assessment work, then the authority should proceed to the Second and/or Third Stage review and assessment.
    Other transport sources

  21. There is the potential for PM10 emissions to arise from other forms of transport, apart from road traffic. These include aircraft, railways and shipping.
  22. It is well recognised that modern types of aircraft emit very low levels of particles. Previous studies which have been carried out within the UK have demonstrated that the impact of aircraft PM10 emissions is negligible at airports with less than about 5 million passengers per year (mppa) throughput, and can be effectively disregarded. For smaller airports ( <5 mppa), authorities may still need to undertake the review and assessment for road traffic emissions, if these are considered to be significant.
  23. PM10 emissions from railways will only be associated with diesel engines. Emissions are too low to have any significant impact alongside railway tracks, but there is the potential for impact where there are large numbers of stationary idling engines, e.g. a major depot or terminus, with sensitive properties within close proximity.
  24. Shipping movements may also give rise to PM10 emissions, but, as in the case of railways, there is only the potential for a significant impact where there are large numbers of ships, e.g. major ports with properties within close proximity.
  25. Where authorities have identified the potential for these impacts, it is recommended that a modelling study is completed as part of a Third Stage review and assessment.
Overview          Second Stage
Report prepared by Stanger Science and Environment
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