Benzene, annual average concentration in the Netherlands, 1991-2003
The annual average benzene concentration has fallen sharply since 1996 and would appear to have stabilised since 2000. The annual average benzene concentration has not exceeded the standard in the last ten years.
Benzene concentrations declining until 2000 and then stable
The trend for the annual average benzene concentration is downwards, and this is seen most clearly at street stations. The concentrations at street stations have fallen by more than half in the last seven years. The concentrations seem to have stabilised since 2000. The striking fall since 1996 is mainly the result of the introduction of the closed-loop three-way catalytic converter, technical improvements in passenger cars and the reduction of the concentrations of benzene in petrol. With effect from 1 January 2000, the standard for concentration of benzene in petrol was lowered from 5% to 1% (Staatsblad, 1999). However, samples taken by the environmental inspectorate showed that petrol already complied with this new standard in October 1999. The average concentration of benzene in petrol was between 2 and 2.5 per cent in the 1990s.
No exceedances of standard
The annual average background concentration of benzene in 2003 was 0.6 µg/m3. The annual average background concentrations varied between 0.1 en 3.7 µg/m3 in 2003. The European 2010 limit value of 5 µg/m3 for the annual average benzene concentration has not been exceeded in the Netherlands for a number of years now. Until 1 January 2006, the effective standard is 10 µg/m3 because of the permitted exceedance of 5 µg/m3.
Highest concentrations in urban areas with industry
Increased concentrations are mainly found in urban areas in the Randstad urban agglomeration. The highest values are found in urbanised areas with a lot of industrial activity, so that the contributions from traffic and major point sources from the storage and transhipment of fuels coincide. This situation is found, for example, in the Rijnmond (Rhine estuary) area.
European standards for exposure to benzene
The EU has adopted a number of limit values for the concentration of benzene in air in order to protect the public against the effects of chronic exposure. Since December 2000, a new EU standard has been in force on the basis of the '2nd daughter directive'. The new EU standard provides for a limit value of 5 µg/m3 with a permitted exceedance of 100% until 1 January 2006. The permitted exceedance then starts to decline by 1 µg/m3 annually to 0%. From 1 January 2010 onwards, then, compliance with the limit value van 5 µg/m3 will be required.
Sources of benzene
Benzene is a volatile aromatic component of petrol, and road traffic is an important source. More than half of the benzene in the Netherlands is from foreign sources. This is because benzene remains in the atmosphere for a fairly long time (a few days). The highest concentrations are found in urbanised areas with a lot of industrial activity and close to motorways because of the effect of local sources.
Impact of benzene on health
Benzene has a toxic action on blood and blood-forming tissue. Benzene is also a carcinogen; exposure can result in leukaemia.
Compared to other risk factors, aromatics at the current concentrations are considered to represent a limited risk only. Exposure to some aromatics, the best known of which is benzene, can harm health. De Hollander and Brunekreef estimate the mortality rate caused by benzene in the Netherlands at three a year. The estimate for benzene in terms of disability adjusted life years is 140 DALYs/jaar.
Exposure of the public to benzene
The Dutch public is exposed to relatively low benzene concentrations that are well below the prevailing limit. In 2003, less than 1% of the population suffered chronic exposure to annual average background values of benzene in excess of 2 µg/m3 (2.0 - 3.7 µg/m3).
