Chromium Pollution Decreases Across the UK

Scientists at the National Physical Laboratory (NPL) have detailed the changing levels of chromium pollution across the UK Heavy Metals Monitoring Network, which celebrates 10 years of NPL operation this month.

Chromium, a toxic metal, is being increasingly recognised as an important environmental pollutant, and its emission from industrial facilities is controlled by European legislation.

Researchers at NPL and the University of Southampton found that ambient chromium concentrations, measured at stations in the UK Heavy Metals Monitoring Network, have decreased by an order of magnitude since 1980 in line with emissions reductions.

The researchers also presented a novel method for cheaply and effectively assessing levels of the more toxic form, chromium(VI), using water soluble chromium concentrations as a proxy measure. Chromium(VI) compounds are known carcinogens, with hexavalent chromium's toxicity arising from its ability to bind to cellular macromolecules.

The new method suggested that almost half of samples collected in 2012 and 2013 contained chromium(VI) levels exceeding the limit proposed by the Department for Environment, Food and Rural Affairs' (Defra) Expert Panel on Air Quality Standards.

The publication coincides with this month's 10 year anniversary of NPL's operation of the UK Heavy Metals Monitoring Network on behalf of Defra.

The Network, consisting of 25 monitoring stations across the UK, takes measurements of heavy metal concentrations in the air to assess compliance with European legislation. During the 10 years, over 15,000 samples have been analysed, producing more than 100,000 individual results of the concentrations of various toxic metals in the air.

As a UK Air Quality Reference Laboratory, NPL is responsible for producing accurate and traceable data in support of the UK's obligations under EU Air Quality Directives. Besides the Heavy Metals Network, NPL operates three more of the UK's air quality networks for Defra, including the Polycyclic Aromatic Hydrocarbons Network.