Concentrations of heavy metals in air in the Netherlands, 1990-2002
The average annual concentrations in air of arsenic, cadmium, lead and zinc have been stabilising in recent years. The standards for these substances are not being exceeded.
Concentrations of heavy metals in air stabilizing
In recent years, the average annual concentrations in air of the heavy metals arsenic, cadmium, lead and zinc have been stabilising. The standards for these substances are not being exceeded.
Since 1990, the concentrations in air of arsenic, cadmium and zinc have been approximately halved. The concentration of lead in air has actually fallen by approximately 80%. These reductions are due to:
- the reduction of the emissions of arsenic in the energy sector (prior to 1995);
- the fall in the cadmium emissions from the Industry and Waste treatment target sectors and abroad;
- the fall in the emissions of lead from traffic;
- the reduction of zinc emissions from the Industry and Waste treatment target sectors.
Cadmium deposition halved since 1990
The precipitation (deposition) of cadmium has fallen by an estimated half in the Netherlands in twelve years. Cadmium deposition in 2002 has been estimated to be a few tenths of a gram per hectare and is therefore within the desired quality standard of 1 g/ha/yr.
Standards for heavy metals in air
The EU has adopted a number of limit values for the concentration of lead in air in order to protect public health (EU, 1999). The European limit value for the annual average lead concentration is 500 ng/m3 and this has applied in the Netherlands since 2001 (Staatsblad, 2001).
Recently, the EU Commission produced a proposal for a new directive for the protection of the public relating to arsenic, cadmium, mercury, nickel and polycyclic aromatic hydrocarbons in ambient air (EU, 2003): the "fourth daughter directive". This proposal contains assessment thresholds for the average annual concentrations of arsenic and cadmium in air; these are, respectively, 6 ng/m3 and 5 ng/m3. There have been no exceedances of the proposed assessment thresholds for arsenic and cadmium in the Netherlands in the last twelve years.
Alongside the statutory quality objectives, the Netherlands uses MAC values and safety-reporting values for concentrations in air of arsenic; these are, respectively, 500 and 5 ng/m3 (VROM, 1999). For the deposition of cadmium, there is a desired quality standard for the protection of ecosystems of 1 g/ha/yr (VROM, 1999). The Netherlands does not have a quality objective for the concentration in the air of zinc.
Sources of heavy metals in air
Industry, traffic and consumers are the main sources of heavy metals in the air. Heavy metals are also released during incineration processes at refineries and during waste disposal. The metals occur mainly in aerosol form. To reduce emissions of cadmium and lead, the Netherlands signed a protocol in 1998 drawn up by the UNECE Conventional on long-range transboundary air pollution (UNECE, 1998).
Impact of heavy metals on health
Heavy metals enter the body either directly from the air, by inhalation, or via food. Because heavy metals are only eliminated from the body slowly, they may accumulate. Prolonged human exposure to heavy metals can ultimately result in health problems.
- Prolonged exposure to arsenic can result in skin or lung cancer.
- Cadmium is a carcinogenic substance.
- Lead in humans results in impaired coordination and mental capacity, as well as damage to the kidneys, nervous system and red blood cells.
