Air quality

Review and Assessment of Airborne Lead

Information about air quality in solihull

6 Review and Assessment of Airborne Lead

6.1 The Government

has adopted a running annual mean of 0.5 µg/m³ as an air quality standard for lead, with an objective of meeting that standard by the end of 2004. In addition, a lower air quality objective of 0.25 µg/m³ is to be achieved by the end of 2008. Given an averaging period of one year, the focus of the review and assessment should be on non-occupational exposures at near ground level locations, including:

• Background locations,
• Roadside locations, such as on pavements or close to the facades of buildings,
• Near industrial premises, which are capable of emitting lead,
• Other locations where people may be regularly exposed, such as schools or hospitals.

6.2 Lead

is the most widely used non-ferrous metal and has a large number of industrial applications, both in its elemental form and in alloys and compounds. The single largest use globally is in the manufacture of batteries, 60 to 70% of the world consumption of some 4 million tonnes of lead, but other uses are as a pigment in paints and glazes, in alloys, in radiation shielding, tank lining and piping. As the compound tetraethyl lead, it has been used as a petrol additive to enhance the octane rating.

6.3 Most of the lead found in the atmosphere

near ground level in Britain, is likely to have resulted from human activity.

6.4 Most of the airborne emissions of lead

in the United Kingdom arose from the combustion of tetra ethyl lead in petrol engined motor vehicles. But these emissions have diminished with the gradual reduction in the use of leaded petrol, through the 1990s, and culminating in its withdrawal from general sale in 1999.

6.5 The main sources of lead

for non-occupational exposures, are now emissions from a number of industrial processes.

However, there are no known industrial sources of lead in Solihull.

Sources of Lead in the West Midlands

Figure 6.1

6.6 Airborne Lead Levels in the West Midlands

Airborne lead was monitored extensively within the West Midlands from 1975 until 1992. Nine monitoring stations were in operation, three each by busy roads, in industrial areas and in residential areas. Figure 6.2 shows the trend in the levels of airborne lead, as measured in the West Midlands, between 1975 and 1992. The change in slope of the curve around 1985 reflected a change in regulations, which reduced the maximum permitted level of lead in petrol from 0.4 g/l to 0.15 g/l.

Trends in West Midlands Air Quality Lead: Annual Mean Roadside Values

Figure 6.2

6.7 Future Trends in Airborne Lead Levels

Government considers that the levels of lead in air, arising from road traffic will be negligible in the future.

The only significant sources of airborne lead in future will be industrial sources.

Measurements made as part of National surveys of lead in air indicate that the roadside values have continued to fall through the 1990s, to around 0.1µg/m³ and urban background levels have fallen to around 0.05µg/m³ (LAQM.TG4(00): Table 5.1). Figure 6.3 shows how the annual average concentrations of airborne lead are expected to change over the next decade.

Forecasts in West Midlands Air Quality Lead: Annual Mean Roadside Values

Figure 6.3

Examination of the records of measurements of airborne lead around Birmingham's main source of lead, a battery manufacturing process, indicates that, allowing for the dispersion of the pollutant, the levels of lead in air at adjacent premises, meets the 0.5 µg/m³ standard. The situation regarding the 2008 objective will be reviewed in the next round of Review and Assessment, once the results of the DETR survey has been published and their guidance has been updated.

Given that the ambient levels of airborne lead already meet both the 2004 and 2008 objectives in Solihull and that the levels are unlikely to rise again, the objectives should continue to be met throughout the Borough.