PM10 concs in UK section 7
7 PM10 Projections for monitoring sites in industrial areas
Several of the PM10 monitoring sites within the national monitoring network are known to be in industrial areas, where industrial emissions may have a significant impact on ambient air quality. Regression analysis of measured PM10, NOx and sulphate concentrations using the same method as successfully applied to urban background monitoring sites in section 5 yielded very poor correlation coefficients and large intercepts for the four sites listed in Table 7.1. This was because no attempt had been made to account for the local industrial source contribution to measured PM10 at these sites. The local industrial source contribution to PM10 at these sites will not have the same temporal variation as the contribution from local traffic sources.
The receptor modelling methods have been extended further in order to separate the measured daily mean PM10 concentrations at these sites into the following sources:
- Primary combustion - calculated from the measured daily mean NO
x concentrations at the industrial site by multiplying by a typical coefficient (A) derived at sites where traffic is the dominant source of both NOx and primary combustion PM10 (A = 0.15).
Secondary - calculated from the measured daily mean sulphate concentrations at the nearest rural monitoring site by a typical coefficient (B) derived at other sites (B = 2.22).
Other - taken from the receptor modelling results for other sites (Bristol Centre for the South Wales sites and Newcastle Centre for the Teesside sites) and calculated by difference ('other' PM10 = Urban Centre site PM10 - primary combustion - secondary). This approximately corresponds with the urban background concentration of coarse particles.
Industrial - calculated by difference (Industrial site PM10 - primary combustion - secondary - other).
Table 7.1 shows the contributions that each of these sources is estimated to contribute to the 1997 annual mean. Both Port Talbot and Redcar look to have significant industrial contributions, while the contributions at Swansea and Middlesbrough are small.
Table 7.1. Estimated contributions to annual mean PM10 concentrations at industrial sites in 1997 (mgm-3)
| Site |
total |
primary |
secondary |
other |
industrial |
| Port Talbot |
25.7 |
3.8 |
4.9 |
10.5 |
6.5 |
| Swansea |
23.6 |
7.3 |
4.9 |
10.6 |
0.9 |
| Middlesbrough |
19.3 |
4.1 |
5.6 |
8.3 |
1.4 |
| Redcar |
22.4 |
2.9 |
5.2 |
8.1 |
6.1 |
The split between 'industrial' and 'other' sources is the least certain. In our projections of business as usual PM10 concentrations for future years listed in Table 7.2 we have, however, assumed that both of these contributions will remain at 1997 values. The primary combustion and secondary particle concentrations have been projected using the same business as usual scenario as used for the background and roadside projections. The NAQS 99th percentile is expected to be at least 70 mgm-3 at Port Talbot and Middlesbrough and about 50 mgm-3 at Swansea and Redcar. Possibly of more concern are the EU stage 1 90th percentiles, which are projected to be 52 mgm-3 at Port Talbot and 47 mgm-3 at Redcar.
We have also examined the wind directions corresponding to the top 10 days with the highest industrial contributions and these are listed in Table 7.3. This analysis clearly indicates the impact of the steel works at Port Talbot, which is about 750 m to the SW of the monitoring site. This same steel works is about 10 km to the east of the Swansea site and the industrial contributions are correspondingly lower. The Teesside steel works is about 2 km to the NW of the Redcar site.
This analysis does not provide a definite indication of a significant industrial source contribution on a particular days because this component has been derived by difference. A good example of this is provided by the Middlesbrough monitoring site, which experienced extremely high concentrations of PM10 on the 5th November 1997, due to an enthusiastic bonfire celebration taking place immediately adjacent to the site.
