lead summary

Regulations on gasoline lead content were first introduced in Germany (1971) and later the European Union (EU) (1978), to counter the rapid rise in atmospheric lead emissions brought about by the motorization of the masses from the 1950s to the 1970s. The history of these regulations, and their impacts on the German industrial markets, is reviewed in Hagner (2000) . It has two main periods: its rise from the 1930s to the 1970s, and its regulated stepwise reduction from the 1970s to present.
With a gasoline lead content of 0.6 g/l and ever-growing road traffic, automobile lead emissions rose sharply in Europe up to the mid-1970s. Germany, where in the 1970s environmental concerns weighed heavily in national politics, was the first to impose gasoline-lead restrictions. Starting in 1972, German production and importation of gasoline with more than 0.4 g Pb/l was prohibited, and starting in 1976 the more strict limit of 0.15 g Pb/l was imposed. The EU modestly fixed its limit at 0.4 g Pb/l starting 1978.
In 1983, "unleaded" gasoline (0.013 g Pb/l) was introduced in Germany and its exclusive usage was highly desired because a new combustion catalyst which reduced NOx, CO and CxHy emissions was averse to lead. These gases were mass pollutants thought to pose a threat to forests, and the German government wanted to introduce car-emission regulations as strict as those already in place in the US and Japan. However, it was now not possible to prohibit the sale of leaded gasoline in Germany because the EU precluded trade restrictions among its members. Instead, Germany introduced tax incentives for unleaded gasoline in 1984, and in 1985 its availability at all German gas stations became mandatory. Enhanced tax incentives in 1986 made German unleaded gasoline cheaper than the leaded variety and its market share in this country has increased steadily thereafter, approaching full share today (over 98%).

In addition to pursuing national policies, Germany also pressed the EU for a European bill. Germany's concerns included transboundary pollution, cross-border traffic and, finally, the viability of its automobile export industry (which had adopted the new lead-averse catalysts). In 1985 the EU mandated that by October 1989 Super unleaded gasoline be available for sale in all member states, alongside the leaded variety. Moreover, member states were asked to voluntarily adopt a 0.15 g Pb/l limit. While adherence to unleaded gasoline was quite prompt in Italy and the UK, France offered strong resistance, partly to protect its small-car export industry. In 1987, all member states were allowed to prohibit national production and sales of leaded 92-octane gasoline. Observable damage to public health and the environment was claimed.
Similar arguments led to the signing, by nearly all countries in Europe of the 1998 Aarhus treaty (COWI and DTI, 1998), which stipulates the exclusive usage of unleaded gasoline in Europe by the year 2005 ( "Environment for Europe" Ministerial Conference in Aarhus, Denmark).

Expert estimates of lead emission rates were produced for 1955, 1965, 1975, 1985, 1990 and 1995 (Pacyna and Pacyna, 2000)(see figure) . Forecasted emissions for 2010 were also produced. The estimated past emissions indicate that, even though gasoline consumption continued to rise after the 1970s, lead emissions in Europe by this major source decreased dramatically as a result of the increasingly stringent regulations, from an estimated 119 thousand tones (tt) in 1975 to just 19.5 tt in 1995. In Germany, annual lead emissions from gasoline conbustion dropped from over 11 tt in 1985 to just a few hundred tones in 1992, even though gasoline sales continued to rise (see figure) .
Despite the steep decline of this lead source since the 1970s, gasoline combustion has nevertheless remained the largest lead source in Europe, and is predicted to maintain this position in year 2010 (Pacyna and Pacyna, 2000). This was possible because the other major lead sources were also drastically reduced as a result of manufacturing process and economic changes (see figure) .
The European portion of the former USSR has been the largest lead emitter in Europe throughout these four decades, and is predicted to maintain that position in year 2010 (see figure) . Together, Russia and Ukraine accounted for over one-half of European lead emissions in 1995, a fraction they are predicted to maintain in 2010. The major reason for their comparatively large contribution is their continued usage of leaded gasoline.

3. Reconstruction of weather conditions for Europe from 1958 to 1997

A reconstruction was performed of the European climate conditions in the 40-year period (Feser, Weisse and von Storch, 2001), using the REgional MOdel (REMO, Jacob and Podzun, 1997) and applying the spectral-nudging technique (von Storch, Langenberg and Feser, 2000) . REMO is based on the numerical weather prediction model EM of the German Weather Forecast Service.
A regionalisation of the NCEP reanalyses was performed with REMO, yielding a 40-year (1958-1997) dataset with half-degree spherical resolution and 1 hour temporal resolution. The NCEP reanalyses were used to drive REMO at the lateral domain boundaries, as is conventionally done. Additionally, the spectral nudging technique was used over the entire model domain, forcing REMO to satisfy not only boundary conditions but also the reanalyses large-scale features (>= 750 km) throughout the domain.
The regionalised atmospheric data set was used to force the atmospheric transport model, addressed next.

4. Reconstruction of the long-range transport and deposition of lead

The reconstruction was performed with the single-layer lagrangian model of atmospheric transport and deposition, TUBES (Costa-Cabral, 1999 and 2001) . Simulated lead concentrations and deposition rates were obtained at 6-hour intervals over the 38-year period. Their annual means (see figure and figure ) have generally reproduced the rise-and-fall pattern observed throughout Europe. The average annual percentage of contribution by lead emissions from each country to lead deposition in each other country was computed (see figure) . While larger countries are mostly affected by their own national lead emissions, smaller countries such as Switzerland (see figure) are markedly affected also by the emissions from their neighbors.
This figure shows the simulated and measurement-estimated total annual lead deposition over the Baltic Sea. This figure shows the simulated and measured mean annual air lead concentration from 1990 to 1995 at EMEP coastal stations on the North Sea and English Channel, showing general good agreement despite moderate under-estimation in the Northern part of the North Sea (stations NO99 and GB91) and moderate over-estimation in the English Channel (station GB92). Simulations of mean annual concentration for Central and East-Central Europe show comparatively larger deviations from measurement, with a tendency for over-estimation over Germany and under-estimation over the Czech Republic, but which are mostly within a factor of 2 of estimates based on EMEP-station measurements (see figure) .

5. Some effects in human, animal and plant populations

As a result of decreasing lead concentrations and depositions, measured lead contents in human blood and in animal tissues (such as in mussels) have also dropped markedly. This figure displays measured blood lead levels in Germany. The next figure shows measured and estimated blood lead levels in the German population from 1958 to 1995. Estimates extend back to the time period for which no measured values are available, and are based on the reconstructed (simulated) lead air concentrations. According to these estimates, blood lead levels in the 1970s in Germany may have approached 150 micrograms of Pb per litter of blood, a level for which the German Human-Biomonitoring Commission (1995) expects that for children and women under 45 years of age health dangers cannot be ruled out and controls are recommended. Given lead's neurotoxicity and retarding effect on children's neurological development, scientists from the USA expect negative health impacts on children already at a level of 100 ug Pb/l. Although the lead pollution has improved in industrial countries during the last 4 decades the blood lead levels of the population in the "megacities" in developing countries have increased (see figure) .
Analyses of lead loads in aquatic systems, such as the River Elbe, showed no decline over time in either suspended matter or surface sediments. Regional differences in lead concentrations of fluvial, i.e. riverine systems were found, due to tidal influence, runoff and local emissions. Lead contamination of sediments from the North Sea was highest in estuaries. Concentrations in sediment cores were quite stable down to the depth of background values, due to bioturbation, flow, waves and meandering channels (see figure) .
Terrestrial soils in Europe were highly polluted in industrial and ore mining areas and large cities.
No decline in lead concentrations was evident in foraminifera, bladder wrack or fish. It was found that contamination in sediments, mammals and fish livers was higher in coastal zones than in the open sea (see figure) . In contrast to aquatic organisms, positive impacts of lead reduction regulations were detected in terrestrial plants, which adsorbed or took up lead mainly through atmospheric lead deposition. European lead concentrations in plants decreased coincidently with lead emissions (see figure) .

6. Some economic effects

Environmental protection policies in the automobile market were not implemented until the motorisation of masses in the 1960s which caused an increasing environ-mental burden. From 1950 to 1992, gasoline sales increased substantially (see figure) . This development, however, was mitigated by the oil crisis in 1973 and 1978 which initiated two worldwide recessions. These obviously resulted in a decline in the rate of growth of gasoline sales after 1972. Due to the lead reduction regulations in 1972 and 1976, the total lead emissions first decreased significantly but then rose again. In the years up to 1985, the EU passed several regulations to limit the emission not only of lead in gasoline but also of the mass pollutants CO, CxHy and NOx. The response across the EU was very diverse and obviously not linked to emission levels (see figure) . While Germany, Italy and the United Kingdom reacted quickly, France remained the greatest polluter in the EU. In the latter the environmental protection movement was probably too weak to forward the pollutant reduction process. In any case, the French automobile industry disapproved of emission regulations. They were concerned about severe losses of export markets, because the French automobile export relied on the sales of small cars, whose sale prices would rise above average.
The regulations had several effects on the German mineral oil and automobile markets. Increases in gasoline production costs due to additives with high octane numbers came into force in 1976 and 1986 and were different subject to the type of refinery. In any case, none of the anticipated bottlenecks in gasoline supply occurred because large overcapacities had been built up in the German refinery sector. Several factors had a negative influence on the sales of unleaded gasoline. The price level higher than leaded gasoline, the execution of adaptation measures in the motor and negative comments from both the automobile traders and the media were all important. When unleaded gasoline became cheaper than leaded fuel its market share increased quickly (see figure) . Overall, the price trend of unleaded fuel was not only heavily influenced by varying crude oil prices but also by various tax incentives (see figure 1 and 2) . With regard to the distribution system, the lead reduction policy weakened the market position particularly of the medium-sized traders and the independent importers despite the fact that investment subsidies had been implemented (see figure) .
In the automobile market, favourable terms of competition were experienced by producers of cars with a high technical standard, who had already gathered experience with catalyst systems on the U.S.-market and who offered a broad supply of cars with diesel engines (see figure) . Over time, the additional costs of installing catalyst systems declined. This indicated dropping unit costs due to increasing production of low-emission cars, an effect of economies of scale and strong price competition. The German car industry was the first in the EU to change its production to low-emission automobiles so that it could realise trade benefits. The EU classification of diesel engines as low-emission cars and tax incentives for automobiles with engines of low cubic-capacity benefited particularly the French, Italian, English and Japanese automobile imports to Germany.
The gasoline lead content regulations had no significant effects on economic indicators such as unemployment level, economic growth, price stability and foreign trade balance. Innovations were encouraged, and competition was strengthened so that the tendency for collaboration in the gasoline and automobile markets was weakened. Furthermore, no significant allocation effects occurred, because the costs to reduce lead in gasoline were broadly compensated by the tax discrimination between leaded and unleaded gasoline, tax subsidies for mo-torists and investment subsidies for gasoline traders.